Solar energy Essay Example | Topics and Well Written Essays - 500 words

Solar energy - Essay Example Organizations and industry likewise utilize these technologies to broaden their energy sources, enhance productivity, and recovery cash. Sun based photovoltaic and concentrating sun powered force technologies are likewise being utilized by engineers and utilities to process power on a monstrous scale to power urban communities and residential areas. Sun powered force is generated by gathering daylight and changing over it into power. This is carried out by utilizing sun powered boards, which are vast even boards made up of numerous singular sunlight based cells. It is frequently utilized as a part of remote areas, in spite of the fact that it is getting to be more famous in urban territories too. This page holds articles that investigate propels in sunlight based energy engineering. Numerous individuals are acquainted with supposed photovoltaic cells, or sun powered boards, found on things like space apparatus, housetops, and handheld adding machines. The cells are made of semiconductor materials like those found in PC chips. The point when daylight hits the units, it thumps electrons detached from their molecules. As the electrons course through the unit, they produce power. On a much bigger scale, sunlight based warm power plants utilize different strategies to think the suns energy as a high temperature source. The high temperature is then used to bubble water to drive a steam turbine that produces power in much the same form as coal and atomic force plants, supplying power for many individuals. Sun powered energy is praised as a limitless fuel source that is contamination and regularly commotion free. The engineering is likewise flexible. For instance, sun based units produce energy for far-out spots like satellites in Earth circle and lodges profound in the Rocky Mountains as effectively as they can control downtown edifices and cutting edge autos. However sun powered energy doesnt work

Homoeostasis Case Study Example | Topics and Well Written Essays - 250 words

Homoeostasis - Case Study Example Any fluctuation in the blood glucose concentration is detected by the pancreas, which in turn responds by secreting insulin. The secreted insulin increases the conversion of glucose to glycogen. As a result, Mary’s blood glucose concentration reduces (IHW 2006). Trekking causes excess loss of water from the body in the form of sweat. As a result, the osmolality of the blood plasma rises. The increasing osmolality (stimulus) of the plasma is detected by the hypothalamus (receptor/coordinating center), triggering the secretion of ADH. ADH (effector) causes the opening of aquaporin channels in the collecting ducts of the kidney. In the process, more water is reabsorbed from the urine into the bloodstream. The reabsorption of more water (response) reduces the osmolality of the plasma. However, if alcohol is ingested, it inhibits the secretion of ADH, making the aquaporin channels to close. As a result, the body loses more water in the form of dilute urine (MMHE n.d., p. 1192). Since Jason had put on a short sleeve shirt, the peripheral nerve receptors in his skin detected the surrounding temperature and relayed an appropriate message to the hypothalamus. The hypothalamus in turn stimulated his skeletal muscles, causing him to shiver. Although the shivering generated heat by friction, it was not sufficient to normalize Jason’s body temperature. However, when Jason decided to run, the activity in his muscles intensified and generated sufficient heat to keep him warm. As a result, the shivering stopped because his body had gained the necessary heat (Docherty & Foudy 2006, p. 20). Dampney, RAL, et al. (2006). Central mechanisms underlying short-term and long-term regulation of the cardiovascular system. Available at: http://www.ncbi.nlm.nih.gov/pubmed/11985533 [Accessed 11 December

Students in AP World History Essay Example for Free

Students in AP World History Essay Students in AP World History are expected to be able to write three different types of essays: a document-based question (or DBQ), a change-over-time essay, and a comparative essay. You can probably gather from the names what you need to do in each essay – the document-based question provides you with a set of documents on which to base your essay; the change-over-time essay asks you to analyze the changes and continuities that occurred within a certain period of time; and the comparative essay asks you to compare and contrast two episodes, cultures, religions, or other historical phenomenon from a given period. Writing a thesis for an AP World History essay is a little different from other theses you may have learned to write in English or Oral Communications. Luckily, there is a basic format you can use for each of the three essays. The key to writing a good AP World History essay is to tell the reader what you are going to talk about before you talk about it. The AP World History Exam refers to this as your thesis. The scoring rubric (the guidelines readers use to score your essays) requires readers to answer the following questions about each of your essays: †¢ Do you have a comprehensive, analytical, and explicit thesis? †¢ Is your thesis acceptable? So how does a person write a comprehensive, analytical, and explicit thesis? What needs to be included? What is an â€Å"acceptable† thesis and what is an â€Å"unacceptable† thesis? Put simply, an analytical thesis will use specific details that will allow the reader to understand exactly what you are talking about. A good thesis is never just one sentence; it is a group of statements. Therefore, you will start with a general sentence, but you have to then follow it up with additional sentences that provide all the necessary elements described above. Together, these statements must †¢ restate the prompt and define terms, context, and chronology of events under discussion †¢ address each part of the question (include both a similarity and a difference or both a continuity and a change) †¢ Make a transition statement to the body of the essay with a sentence like â€Å"The historical evidence would indicate that † A strong analytical thesis will serve as a â€Å"road map† for the remainder of your essay and show the reader that you are on target with answering the question. The Prompt Each AP World History Essay exam will have a prompt, or question, that you will write on. An example of a prompt would be this: Compare the economic, social, and political characteristics of ancient Mesopotamia and ancient Egypt. The first thing to remember is that when it says â€Å"compare,† what the prompt really means is for you to both â€Å"compare† and â€Å"contrast. † AP exam readers will expect you to know this! You will need to note both similarities and differences. The Thesis The first sentence of your thesis should be a restatement of the prompt. Before you begin writing, you should first underline important information in the prompt. In the sample above, you would want to underline the words social, political, economic, ancient, Mesopotamia, and Egypt. You will then use those words to create the first sentence of your thesis. Here is how that might look: â€Å"Two ancient civilizations, Mesopotamia and Egypt, created complex societies with distinct social, political, and economic characteristics. † The second sentence of your thesis should address both a similarity and a difference. You will simply list them in the thesis. Do not analyze them. Save them for analysis later in your paper. Here is how your second sentence might look: â€Å"One similarity is that both civilizations developed strong economies based on trade with other cultures. One difference is that the Mesopotamians traded with people across the Indian Ocean in South Asia, while the Egyptians traded with their neighbors to the south in Nubia. † The third and final sentence of your thesis should be the transition into your essay. It is here that you will help your reader get from your introduction into the bulk of what you have to say. Here is how your third sentence might look: â€Å"â€Å"The historical evidence would indicate that the two civilizations of Mesopotamia and Egypt had some subtle differences, but were, for the most part, nearly identical. †

Microwave Remote Sensing in Forestry

Microwave Remote Sensing in Forestry BACKGROUND: Microwave remote sensing at wavelengths ranging from 1 cm to 1 m has gained a lot of importance over the past decade for a wide range of scientific applications with the availability of active radar imaging systems. Its potential in spatial applications has been scientifically established in various sectors like forestry, agriculture, land use and land cover, geology and hydrology. A variety of applications have been carried out world over using microwave data like discrimination of crop types, crop condition monitoring, soil moisture retrieval, delineation of forest openings, estimation of forest above ground biomass, forest mapping; forest structure and fire scar mapping, geological mapping, monitoring wetlands and snow cover, sea ice identification, coastal windfield measurement, wave slope measurement, ship detection, shoreline detection, substrate mapping, slick detection and general vegetation mapping (Kasischke et al., 1997). There is an emerging interest on microwave remote sensing, as microwave sensors can image a surface with very fine resolution of a few meters to coarse resolution of a few kilometers. They provide imagery to a given resolution independently of altitude, limited only by the transmitter power available. Fundamental parameters like polarization and look angle can be varied to optimize the system for a specific application. SAR imaging is independent of solar illumination as the system provides its own source of illumination. It can operate independently of weather conditions if sufficiently long wavelengths are chosen. It operates in a band of electromagnetic spectrum different from the bands used by visible and infrared (IR) imageries. Microwave applications in Forestry Applications of microwave remote sensing in forestry have also been reported during the recent past. Recent reviews on the application of radar in forestry show that SAR systems have a good capability in discriminating various types of (tropical) forest cover using multi-temporal and multi-frequency SAR data (Vander Sanden, 1997; Varekamp, 2001; Quinones, 2002; Sgrenzaroli, 2004). These studies showed that the biomass dependence of radar backscatter varies as a function of radar wavelength, polarization and incidence angle. Also recent studies have demonstrated that synthetic aperture radar (SAR) can be used to estimate above-ground standing biomass. To date, these studies have relied on extensive ground-truth measurements to construct relationships between biomass and SAR backscatter (Steininger, 1996; Rignot et al., 1997). Many studies demonstrated the use of Synthetic Aperture Radar (SAR) remote sensing to retrieve biophysical characteristics from forest targets (Richards, 1990). Although radar backscatter from forest is influenced by their structural properties (Imhoff, 1995), earlier studies derived useful relationships between backscattering coefficients and the above-ground biomass (Baker et., 1994; Le Toan et al., 1992; Dobson et el., 1992; Imhoff; 1995). These relationships may provide a method of monitoring forest ecosystems which play such a vital role in carbon storage and NPP. Microwave remote sensing has the advantage of all weather capability coverage overcoming the persistent problem of cloud cover in satellite images like in optical data. Optical remote sensing is being used very successfully in various applications related to earth resources studies and monitoring of the environment. However, optical remote sensing is not suitable for all atmospheric conditions. It cannot penetrate through clouds and haze. In many areas of the world, the frequent cloud conditions often restrain the acquisition of high-quality remotely sensed data by optical sensors. Thus, radar data has become the only feasible way of acquiring remotely sensed data within a given time framework because the radar systems can collect Earth feature data irrespective of weather or light conditions. Due to this unique feature of radar data compared with optical sensor data, the radar data have been used extensively in many fields, including forest-cover identification and mapping, discrimi nation of forest compartments and forest types, estimation of forest stand parameters and monitoring of forests. In areas where vegetation cover is dense, it visually covers the underlying formation and it is very difficult to detect structural limiting the use of optical sensors. Radar however, is sensitive enough to topographic variation that it is able to discern the structural expression reflected in the tree top canopy, and therefore the structure may be clearly defined on the radar imagery. Based on this background, the current thesis work has been carried out to explore the potential of microwave data in addressing core areas of tropical forestry viz., vegetation classification, above ground biomass estimation etc., and to provide the users/researchers a meaningful data base of SAR applications in tropical forestry, specifically over the India region. Research questions: Which SAR wavelength/frequency band is appropriate for vegetation classification in tropical forests? To what extent above ground biomass can be measured in tropical forests? Which frequency band and polarization are suitable for above ground biomass estimation? Is there any enhancement in vegetation classification with polarimetric / interferometric data than stand alone amplitude data? Research hypothesis: Based on the previous studies and earlier mentioned research questions, we understand that the backscatter increases with the increase in above ground biomass and depends on wavelength bands, polarizations used and on the study area, topographic variations and species composition. So, the present study attempts to derive the application potential of airborne and space borne SAR data in the quantification of the forest resources in tropical regions like India, both as a complementary and supplementary role to optical datasets. Different techniques such as Regression analysis, multi-sensor fusion, texture measures and interferometric coherence characterize different biomass ranges of the test sites and classification of major land cover classes. This study would facilitate scope for future research in tropical regions to explore the potentials of SAR data in land cover classification and above ground biomass estimation using the polarimetric and interferometric techniques. OBJECTIVES: Based on this background, the present study aims at the following objectives: Vegetation type classification using polarimetric and interferometric SAR data. Forest above-ground biomass estimation using multi-frequency SAR data and ground inventoried data. Vegetation classification is necessary to understand the diversity of species in a given area which gives above ground biomass with measured parameters. Hence, vegetation classification enhances the estimation of the above ground biomass. Forest biomass is a key parameter in understanding the carbon cycle and determining rates of carbon storage, both of which are large uncertainties for forest ecosystems. Accurate knowledge of biophysical parameters of the ecosystems is essential to develop an understanding of the ecosystem and their interactions, to provide input models of ecosystem and global processes, to test these models and to monitor changes in ecosystem dynamics and processes over time. Thus, it is a useful measure for assessing changes in forest structure, comparing structural and functional attributes of forest ecosystems across a wide range of environmental conditions. Knowing the spatial distribution of forest biomass is important as the knowledge of biomass is required for calculating the sources and sinks of carbon that result from converting a forest to cleared land and vice versa, to know the spatial distribution of biomass which enables measurement of change through time. Field sampling is the most followed conventional method for vegetation type classification. The identification of different species in field yields good results in the estimation of the above ground biomass. It is very time consuming, expensive and very complicated. With the use of multiple sensors, varied data collection and interpretation techniques, remote sensing is a versatile tool that can provide data about the surface of the earth to suit any need (Reene et al, 2001). Remote sensing approach for vegetation classification is cost effective and also time effective. Though the identification of the tree species is possible only from the aerial imagery, major forest types can be identified from the airborne and the spaceborne remote sensing data. Visual image interpretation provides a feasible means of vegetation classification in forests. The image characteristics of shape, size, pattern, shadow, tone and texture are used by interpreters in tree species identification. Phenological correlations are useful in tree species identification. Changes in the appearance of trees in different seasons of the year some times enable discrimination of species that are indistinguishable on single dates. The use of multi-temporal remote sensing data enabl es the mapping of the different forest types. SAR has shown its potential for classifying and monitoring geophysical parameters both locally and globally. Excellent works were carried out on the classification using several approaches such as polarimetric data decomposition (Lee et al., 1998), knowledge based approaches considering the theoretical backscatter modeling and experimental observations ( Ramson and Sun , 1994) ; Backscatter model-related inversion approaches ( Kurvonen et al., 1999), neural networks and data fusion approaches ( Chen et al., 1996). Dong et al. (2001) have shown that the classification accuracy of 95% for the vegetation classes could be achieved through the segmentation and classification of the SAR data using Gaussian Markov Random Field Model (GMRF). Many methods have been employed for classification of polarimetric SAR data, based on the maximum likelihood (ML) (Lee et al. 1994), artificial neural network (NN) (Chen et al. 1996, Ito and Omatu, 1998), support vector machines (SVMs) (Fukuda et al. 2002), fuzzy method (Chen et al. 2003, Du and Lee 1996), or other approaches (Kong et al. 1988, Lee and Hoppel 1992, van Zyl and Burnette 1992, Cloude and Pottier 1997, Lee et al. 1999, Alberqa 2004) Among these methods, the ML classifier (Lee et al. 1994) can be employed for obtaining accurate classification results, but it is based on the assumption of the complex Wishart distribution of the covariance matrix. Assessing the total aboveground biomass of forests (biomass density when expressed as dry weight per unit area at a particular time) is a useful way of quantifying the amount of resource available for all traditional uses. It either gives the quantity of total biomass directly or the quantity by each component (e.g., leaves, branches, and bole) because their biomass tends to vary systematically with the total biomass. However, biomass of each component varies with total biomass by forest type, such as natural or planted forests and closed or open forests. For example, leaves contribute about 3-5% and merchantable bole is about 60% of the total aboveground biomass of closed forests. Many researchers have developed various methods based on field inventory and remote sensing approaches for the estimation of above ground biomass (Kira and Ogawa, 1971). Traditionally, field-measured approach is considered as the most accurate source for above-ground biomass estimation. It has been converted to volume, or biomass, using allometric equations that are based on standard field measurements (tree height and diameter at breast height). Different approaches, based on field measurement (Brown et al. 1989, Brown and Iverson 1992, Schroeder et al.. 1997, Houghton et al., 2001, Brown, 2002); remote sensing (Tiwari 1994, Roy and Ravan 1996, Tomppo et al., 2002, Foody et al., 2003, Santos et al., 2003, Zheng et al., 2004, Lu, 2005); and GIS (Brown and Gaston 1995) have been applied for AGB estimation. Traditional techniques based on field measurement are the most accurate ways for collecting biomass data. A sufficient number of field measurements is a prerequisite for developing AGB estimation models and for evaluating the AGB estimation results. However, these approaches are often time consuming, labour intensive, and difficult to implement, especially in remote areas and are generally limited to 10-year intervals. Also, they cannot provide the spatial distribution of biomass in large areas. For the above reasons, the perspectives of using remote sensing techniques to estimate forest biomass have gained interest. Remote sensing data available at different scales, from local to global, and from various sources, optical to microwave are expected to provide information that could be related indirectly, and in different manners, to biomass information. The possibility that aboveground forest biomass might be determined from space is a promising alternative to ground-based methods (Hese et al., 2005). The advantages of remotely sensed data, such as in repetivity of data collection, synoptic view, digital format that allows fast processing of large quantities of data, and the high correlations between spectral bands and vegetation parameters, make it the primary source for large area AGB estimation, especially in areas of difficult access. Therefore, remote sensing-based AGB estimation has increasingly attracted scientific interest. In general, AGB can be estimated using remotely sensed data with different approaches, such as multiple regression analysis, K nearest-neighbour, and neural network (Roy and Ravan 1996, Nelson et al. 2000a, Steininger 2000, Foody et al. 2003, Zheng et al. 2004), and indirectly estimated from canopy parameters, such as crown diameter, which are first derived from remotely sensed data using multiple regression analysis or different canopy reflectance models (Wu and Strahler 1994, Woodcock et al. 1997, Phua and Saito 2003, Popescu et al. 2003). Spectral signatures or vegetation indices are often used for AGB estimation in optical remote sensing. Many vegetation indices have been developed and applied to biophysical parameter studies (Anderson and Hanson 1992, Anderson et al. 1993, Eastwood et al. 1997, Lu et al. 2004, Mutanga and Skidmore 2004). Vegetation indices have been recommended to remove variability caused by canopy geometry, soil background, sun view angles, and atmospheric conditions when measuring biophysical properties (Elvidge and Chen 1995, Blackburn and Steele 1999). Radar remote sensing has potential to provide information on above ground biomass. The information content of SAR data in terms of the retrieval of biomass parameters will be assessed based on an understanding of the underlying scattering mechanisms, which in turn are derived from observations and modeling results. For this purpose, an analysis of data acquired by multiple frequency, incidence and polarisation systems and by interferometric systems is carried out. It has been proved that the sensitivity to biomass parameters differ strongly at different frequencies, polarisations and incidence angles. In general, long wavelength SAR backscatter (P and L band) is more sensitive to forest biomass than shorter wavelength C-band backscatter and the relationships saturate at certain biomass levels ( Imhoff 1995b). The strength of the relationships and the saturation levels are dependent on the type of forest being analysed (Ferrazoli et al. 1997). The saturation levels for the estimation of above ground biomass depend on the wavelengths (i.e. different bands, such as C, L, P), polarization (such as HV and VV), and the characteristics of vegetation stand structure and ground conditions. C-band can measure forestry biomass up to app. 50 tons/ha, L-band can measure up to 100 tons/ha and P-band can measure up to 200 tons/ha (Floyd et al., 1998). The combination of multiple channels and polarizations provides greater advantage for estimating total biomass (Harry Stern, 1998). RELEVANCE OF THE STUDY: The present study is the part of Radar Imaging satellite Joint Experiment Programme (RISAT-JEP) for forestry applications undertaken by Forestry and Ecology Division of National Remote Sensing Centre (NRSC), as a pilot campaign with specific objectives of above ground biomass estimation and vegetation type classification using airborne DLR (German Aerospace Center) carrying ESAR (Experimental Synthetic Aperture Radar) data for Rajpipla (Gujarat) study site and space borne ENVISAT (Environmental Satellite) carrying Advanced Synthetic Aperture Radar (ASAR) data for three test sites viz., Rajpipla (Gujarat), Dandeli (Karnataka) and Bilaspur (Chattisgarh), India. SCOPE OF THE STUDY: The specific objectives of the present study are above ground biomass estimation and vegetation type classification using airborne DLR (German Aerospace Center) carrying ESAR (Experimental Synthetic Aperture Radar) data for Rajpipla (Gujarat) study site and space borne ENVISAT (Environmental Satellite) carrying Advanced Synthetic Aperture Radar (ASAR) data; ALOS (Advanced Land Observing Satellite) carrying Phased Array L-band Synthetic Aperture Radar (PALSAR) for three test sites viz., Rajpipla (Gujarat), Dandeli (Karnataka) and Bilaspur (Chattisgarh), India. Different techniques such as Regression analysis, multi-sensor fusion, texture measures and interferometric coherence were used to characterize different biomass ranges of the test sites and to classify the major land cover classes using spaceborne C-band ENVISAT-ASAR data and L-band ALOS- PALSAR data. Polarimetric signatures, polarimetric decompositions, multi-sensor fusion techniques etc. were used for the classification of different vegetation types in the Rajpipla study area using the airborne DLR-ESAR data. The study has its uniqueness and gains importance in the application potential of SAR interferometry over tropical regions like India, both in terms of an alternate/substitute to optical data sets due to persisting cloud cover and to the lack of availability of any earlier scientific work over the study region. This study is useful for the applications of to be launched Radar Imaging Satellite (RISAT) in 2010. The study has amply demonstrated the application potential of airborne and space borne SAR data in the quantification of the forest resources in tropical regions like India, both as a complementary and supplementary role to optical datasets. The study would facilitate future research in tropical regions to explore the potentials of SAR data in land cover classification and above ground biomass estimation using the polarimetric and interferometric techniques. LITERATURE SURVEY: During the last decade, many potential applications of SAR in different frequency bands have been studied for forestry applications using data acquired by both airborne and space-borne systems. Various techniques like Polarimetry, Interferometry and Polarimetric-Interferometry enhanced the use of SAR data in forestry applications. The backscatter from vegetation is used to infer information about amplitude data for forest cover mapping and estimation of above ground biomass in regenerating forests. Use of SAR polarimetric data delineated vegetation classes within the forest and also enhanced the capability in estimating the above ground biomass. The use of repeat pass interferometric data enables to calculate the forest stand height and also used for the land cover classification. The emerging Pol-InSAR technique is used to derive the three dimensional forest structures. Forest cover maps were prepared for the boreal, temperate and tropical forests using SAR data. Forest was separated from non-forest regions using multi-temporal C-band ERS SAR data on the test sites of United Kingdom, Poland and Finland (Quegan et al., 2000). The study applied a threshold value to separate forest from other classes. Tropical rainforest of Borneo was mapped from SIR-B data of different incidence angles (Ford and Casey, 1988). Different vegetation covers along with wetlands and clear-cut areas were distinguished. Forest cover mapping was done with JERS-1 SAR data on the coastal regions of Gabon (Simard et al., 2000). The study used decision tree method utilizing both radar amplitude and texture information. Forest cover map was prepared for Southern Chittagong using JERS-1 SAR data (Rahman and Sumantyo, 2007) and the study separated forest, degraded forest, shrubs, coastal plantations, agriculture, shrimp-farms, urban and water. Although radar backscatter from forest is influenced by their structural properties (Imhoff, 1995a), many studies have demonstrated useful relationships between backscattering coefficients and the areal density of above-ground biomass within particular types of forest (Baker et., 1994; Le Toan et al., 1992; Dobson et al., 1992; Imhof et al; 1995b). Many airborne and spaceborne SAR systems have been used to carry out a large amount of experiments for investigating the forest ecosystems. The airborne systems, such as the NASA/JPL AIRSAR, DLR-ESAR, etc., operating at P, L and C band, has been flown over many forest sites (Zebker et al., 1991; Le Toan et al, 1992; Beaudoin et al., 1994; Rignot et al.; 1994; Skriver et al., 1994; Ranson et al., 1996). The experiments of the Canadian CV-580, as well as the European airborne system, mainly operating at C and X band also have been carried out in North America and Europe (Drieman et al., 1989; Hoekman, 1990). Spaceborne SAR is being used from regional to global monitoring in a periodic basis. The spaceborne systems, such as the Seasat SAR, SIR-B, SIR-C/X-SAR and ERS-1, ERS-2, ENVISAT-ASAR, RADARSAT etc., were used for investigations of boreal, temperature and sub-tropical forestry test sites (Ford et al., 1988; Dobson et al., 1992; Ranson et al., 1995; Stofan et al., 1995; Rignotet al., 1995). These experiments and studies have shown that radar is sensitive to forest structural parameters such as diameter at breast height (dbh) and tree mean height including above-ground biomass (Dobson et al., 1992; Pulliainen et al., 1994; Skriver et al., 1994; Ferrazzoli et al., 1995; Ranson et al., 1996). Earlier studies has shown the potential of radar data in estimating AGB (Hussin et al. 1991, Ranson and Sun 1994, Dobson et al. 1995, Rignot et al. 1995, Saatchi and Moghaddam 1995, Foody et al. 1997, Harrell et al. 1997, Ranson et al. 1997, Luckman et al. 1997, 1998, Pairman et al. 1999, Imhoff et al. 2000, Kuplich et al. 2000, Castel et al. 2002, Sun et al. 2002, Santos et al. 2003, Treuhaft et al. 2004). Kasischke et al. (1997) reviewed radar data for ecological applications, including AGB estimation. Lucas et al. (2004) and Kasischke et al. (2004) reviewed SAR data for AGB estimation in tropical forests and temperate and boreal forests, respectively. Different wavelength radar data have their own characteristics in relating to forest stand parameters. Backscatter in P and L bands is highly correlated with major forest parameters, such as tree age, tree height, DBH, basal area, and AGB (Leckie 1998). In particular, SAR L-band data have proven to be valuable for AGB estimation (Sad er 1987, Luckman et al. 1997, Kurvonen et al. 1999, Sun et al. 2002). However, low or negligible correlations were found between SAR C-Band backscatter and AGB (Le Toan et al. 1992). Beaudoin et al. (1994) found that the HH return was related to both trunk and crown biomass, and the VV and HV returns were linked to crown biomass. Harrell et al. (1997) evaluated four techniques for AGB estimation in pine stands using SIR C- and L-Band multi-polarization radar data and found that the L-Band HH polarization data were the critical elements in AGB estimation. Kuplich et al. (2000) used L-band JERS-1/SAR data for AGB estimation of regenerating forests and concluded that these data had the potential to estimate AGB for young, regenerating forests. Sun et al. (2002) found that multi-polarization L-Band SAR data were useful for AGB estimation of forest stands in mountainous areas. Castel et al. (2002) identified the significant relationships between the backscatter coefficient of JERS- 1/SAR data and the stand biomass of a pine plantation. The study observed the improvement in AGB estimation results for young stands, compared to estimation for old stands. Santos et al. (2002) used JERS-1 SAR data to analyse the relationships between backscatter signals and biomass of forest and savanna formations. This study concluded that forest structural-physiognomic characteristics and the radars volume scattering, double bounce scattering are two important factors affecting these relationships. The saturation levels of backscattering co-efficient with respect to AGB depend on the wavelengths (i.e. different Bands, such as C, L, P), polarization (such as HV and VV), and the characteristics of vegetation stand structure and ground conditions. Luckman et al. (1997) found that the longer-wavelength (L-Band) SAR image was more suitable to discriminate different levels of forest biomass up to a certain threshold, indicating that it is suitable for estimating biomass of regenerating forests in tropical regions. Austin et al. (2003) indicated that forest biomass estimation using radar data may be feasible when landscape characteristics are taken into account. The radar backscattering coefficient is correlated with forest biomass and stem volume (Le Toan et al. 1992, Israelsson et al. 1994, Kasischke et al. 1994, Dobson et al. 1995). The sensitivity of Synthetic Aperture Radar (SAR) data to forest stem volume increases significantly as the radar wavelength increases (Israelsson et al. 1997). The imaging process makes SAR suitable for mapping parameters related to forest biomass, like stem volume (Baker et al, 1999; Fransson et al, 1999; Hyyppa et al, 1997; Israelsson et al., 1997; Kurvonen et al, 1999; Pulliainen et al, 1996), total growing stock (Balzter et al, 2000; Schmullius et al, 1997), LAI (Imhoff et al, 1997), or above ground net primary productivity (Bergen et al, 1998). Le Toan et al., (1992) used multi-polarisation L- and P-band airborne radar data, and found that the dynamic range of the radar backscatter corresponded highly with forest growth stages and is maximum at P-band HV polarization. The analysis of P-band data indicated a good correlation between the radar backscatter intensity and the main forest parameters including trunk biomass, height, age, diameter at breast height (dbh), and basal area. Dobson et al., (1992) showed an increasing range of backscatter with changing biomass from C to P-band, as well as higher biomass levels at which backscatter relationships to biomass saturate. Hoekman, (1990) found poor relationships between X- and C-band backscatter and volume and other stand parameters. The spaceborne systems, such as the Seasat SAR, SIR-B, SIR-C/X-SAR and ERS-1, ERS-2, JERS, ENVISAT-ASAR and recently ALOS-PALSAR etc. were used for investigations of boreal, temperature and sub-tropical forestry test sites (Ford et al., 1988; Dobson et al., 1992; Ranson et al., 1995; Stofan et al., 1995; Rignot et al., 1995). These experiments and studies have shown that radar is sensitive to forest structural parameters including above-ground biomass (Dobson et al., 1992; Pulliainen et al., 1994; Skriver et al., 1994; Ferrazzoli et al., 1995; Ranson et al., 1996). Kasischke et al., (1997) reviewed radar data for ecological applications, including AGB estimation. It is being reported in literature that the radar backscatter in the P and L bands is highly correlated with major forest parameters, such as tree age, tree height, DBH, basal area, and AGB. In particular, SAR L-Band data have proven to be valuable for AGB estimation (Sader, 1987; Luckman et al., 1997; Kurvonen et al., 1999; Sun et al., 2002). Kuplich et al., (2000) used JERS-SAR data for AGB estimation of regenerating forests and concluded that these data had the potential to estimate AGB for young, regenerating forests. Luckman et al., (1997) found that the longer-wavelength (L-Band) SAR image was more suitable to discriminate different levels L-Band backscatter shows no sensitivity to increased biomass density after a certain threshold, such as 100 tons ha-1, indicating that it is suitable for estimating biomass of regenerating forests in tropical regions. The radar backscattering coefficient is correlated with forest biomass and stem volume (Le Toan et al. 1992; Israelsson et al., 1994; Kasischke et al., 1994, Dobson et al., 1995). The sensitivity of Synthetic Aperture Radar (SAR) data to forest stem volume increases significantly as the radar wavelength increases (Israelsson et al., 1997). The imaging process makes SAR suitable for mapping parameters related to forest biomass, like stem volume (Baker et al., 1999; Israelsson et al., 1997; Pulliainen et al., 1996), total growing stock (Balzter et al., 2000; Schmullius et al., 1997), LAI (Imhoff et al., 1997), or above ground net primary productivity (Bergen et al., 1998). The dependency of backscatter on above ground biomass was observed and related to the penetration of the radiation into the canopy and interaction with the trunk, where most of the volume, therefore, biomass of the vegetation is concentrated (Sader 1987, Le Toan et al. 1992, Dobson et al. 1992). HV polarization in longer wavelengths (L or P band) is the most sensitive to above ground biomass (Sader 1987, Le Toan et al. 1992, Ranson et al. 1997a) because it originates mainly from canopy volume scattering (Wang et al. 1995), trunk scattering (Le Toan et al. 1992) and is less affected by the ground surface (Ranson and Sun 1994). As forest backscatter in different wavelengths and polarizations originate from separate layers of a canopy, the use of multiple channels or multi-step approaches (e.g., Dobson et al. 1995) could be used to estimate total above-ground biomass (Kasischke et al. 1997). Sun and Ranson (1994) estimated biomass in mixed conifer temperate forest upto 250 Mg/ha. Band ratios (HH/HV and VV/VH) were also used for the above ground biomass estimation. However, Dobson et al. (1995) considered these band ratios too simplistic (as the corresponding backscatter will be much higher for the few tall trees than for the many short ones), although effective in estimating biomass at higher ranges. In spite of this, a combination of bands and polarizations in a multi-step approach made possible the mapping of biomass in a mixed temperate forest upto 250 Mg/ha (Dobson et al. 1995). Establishing a strong link between backscatter and forest variables is an important part of the successful estimation of forest biomass from backscatter. Models are often used to explain the relationship between forest variables, scattering mechanisms and SAR configuration parameters (Richards 1990, Kasischke and Christensen 1990). Another approach is the use of statistical analysis, where forest variables are related to SAR backscatter by regression models (Sader 1987, Le Toan et al. 1992, Rauste et al. 1994). The combination of the two approaches, in most cases to assess the results of the predicted biomass or backscatter via regression (Ranson and Sun 1994, Ferrazzoli et al. 1997, Franson and Israelson 1999). Statistical procedures such as stepwise regression analysis were also used to determine the best set of bands and polarizations to discriminate biomass levels (Ranson et al. 1997a). The three-band (C, L, and P) polarimetric AIRSAR sensor has been used in many forest biomass studies (e.g., Green, 1998; Kasischke et al., 1991, 1995; Moghaddam et al., 1994; Ranson Sun, 1997). The strongest correlation between SAR backscatter and forest biomass has been reported in P-band and the weakest in C-band (e.g., Beaudoin et al., 1992; Dobson et al., 1992; Israelsson et al., 1992; Rauste et al., 1992;

Ensuring Truth Within Creative Nonfiction Essay -- Literary Analysis

The difference between creative nonfiction and fiction is unassuming: fiction is derived from the fabrications of an author’s imagination, whereas creative nonfiction is contingent on facts. A novelist has the freedom to create scenes which never existed, whereas an author of creative nonfiction must convey a truthful story. However, the line between creative nonfiction and fiction, fact and falsehood, has become ever so thin as â€Å"writers of memoir [have been] revealed to be frauds and fiction writers masquerade as memoirists in order to sell books† (Bradley 203). Recent events have revealed authors such as James Frey and Tim Barrus to have combined elements of fiction and nonfiction within their creative nonfiction books (Buck 56), further blurring this line. Overlooked embellishments and whole fabrications were found to exist within their alleged creative nonfiction works – stirring angst within the nonfiction community (Bradley 208). Allegations arose and investigations ensued, all revolving around the question: who is to blame? As a result, the entire creative nonfiction genre received negative publicity and harsh criticism (Bradley 203). For creative nonfiction to restore its legitimacy and veracity as a genre, authors, and not publishers, are to be held responsible for ensuring their creative nonfiction books are truthful. Creative nonfiction, often labeled the â€Å"fourth genre† (Bradley 203), requires the depiction of factual events and happenings through past memories, with a literary touch. Books under this genre include memoirs, biographies, and autobiographies. However, memory is malleable and fades. Hence, authors are given leeway in this respect and to be â€Å"truthful† is defined as an author recollecting and portraying p... ...ate to. For authors to deceive readers knowingly through a creative nonfiction medium is to rob readers of the intrinsic connection and empathy felt towards the story. The story becomes significantly less powerful and not as personally important to the reader. It is then dismissed as fiction, an untrue fairy tale once lost in the nonfiction realm. Writers of creative nonfiction books must then write truthfully to ensure creative nonfiction books are truthful. This is the only practical approach for the creation of true creative nonfiction books. Fact-checking is too onerous a practice when applied to the book publishing industry and avoids the inherent issue at hand: deceitful authors. For the fiction itself created by these authors is not the issue, but the deception, the robbing of unsuspecting readers, which has created this entire mess in the first place.

Jesus Prohibition Against Swearing and His Philosophy of Language :: Jesus Religion Language Prohibition Essays

Jesus' Prohibition Against Swearing and His Philosophy of Language In an article entitled "Oath Taking in the Community of the New Age (Matthew 5:33-37)," Don Garlington calls Jesus' prohibition against swearing an oddity and the avoidance of swearing by certain Christian sects a superficial application of the logion.[1] As a member of one such group, the Mennonites, I offer an apology rather than a rebutal. Mennonites make affirmations rather than swear oaths in order to fulfil Jesus' command often without wondering if they have fulfilled his intention. When they find rationale for their avoidance of oaths, they tend to point to swearing as an occasion for sin rather than something sinful in itself. According to the Mennonite Encyclopedia, one avoids swearing in order to avoid an inadvertant sin of error or the habit of lying when one is not under oath.[2] Both of these reasons for minding the prohibition can be extrapolated from the Matthean text, but neither explains why the act of swearing a truthful oath is from evil. In order to comprehend Jes us' intent, we need to examine Jesus' understanding of language as a human activty that is not always accompanied by mindfulness of the reality that makes it potent, possible, and meaningful. Given that modern usage of "to swear" has come to include the acts of cursing and of using colorful expletives, a definition based upon biblical usage is essential. An oath is a performative utterance; it does not describe something, it does something.[3] According to speech-act theory, an oath accomplishes a number of separate acts. First, it can either expound a view by making a statement of fact regarding past or present events or it can commit the speaker to an obligation in the future. The oath's power to expound or commit relies upon its capacity to execute a second speech-act, the act of invoking God or some divine authority as a witness or guarantor. Finally, the oath puts into place a third speech-act, a conditional curse. Zechariah illustrates the potential of the curse with the metaphor of the flying scroll that consumes the house of any one who swears falsely (Zech 5:1-4). The speech-act of cursing does not depend upon the locutionary act; whether the curse is articulated or not the deed is done.[4] If one's oath proves to be false, God is justified in enacting the curse.[5] Speech-act theorist John Austin describes how oaths can go wrong under the rubric of the doctrine of the infelicitous.

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HIGHER SCORE TOEFL, TOEIC and IELTS classes for serious students How to Paraphrase Effectively Introduction â€Å"Paraphrase† is a verb which means to re-write a phrase or sentence with the same meaning but using different words. Paraphrasing is a very important skill for most English tests, including TOEFL iBT, IELTS and TOEIC Speaking and Writing. In TOEFL iBT, for instance, paraphrasing is an important skill in the reading section, in the listening section and, above all, in the speaking and writing sections of the test. Here is a quick example of paraphrasing using a phrase from the paragraph above: 1. Paraphrasing is a very important skill for most English tests. † 2. â€Å"For many tests of English, being skilful at paraphrasing is extremely important. † Notice how the paraphrased version (sentence 2) changes some vocabulary (e. g. , â€Å"extremely† for â€Å"very†), changes the word order (e. g. , â€Å"tests of English† for â€Å"Eng lish tests†) and changes the grammar (e. g. , â€Å"being skilful at paraphrasing†¦Ã¢â‚¬  for â€Å"Paraphrasing is a very important skill†¦Ã¢â‚¬ ) These are the three main ways to paraphrase and by combining all of these methods, you can achieve clear and accurate paraphrased sentences.The next sections will look at these methods in more detail. Paraphrasing Method 1: Use Different Vocabulary with the Same Meaning Most students try to use this method, but actually it can be difficult to use. The reason is that although English has many synonyms such as ‘large’ or ‘big’, it is unusual for these words to have exactly the same meaning. So, if you try to use a lot of synonyms when you paraphrase, you might produce sentences that are not natural English. Unnatural sentences are likely to reduce your score more than small mistakes because the reader may not understand what you are trying to say.For example, look at this original sentence and two paraphrased equivalents: 1. â€Å"It can be difficult to choose a suitable place to study English. † 2. â€Å"It is often a challenge to pick up (x) a relevant (x) school to learn English. † 3. â€Å"It is sometimes hard to select an appropriate place to learn English. † For non-native speakers, these three sentences might look like they have the same meaning. For native speakers, however, sentence 2 is unnatural. The first problem is â€Å"pick up†. This expression does NOT have the same meaning as â€Å"choose†, so this part of the paraphrased sentence is actually wrong.The second problem is the word â€Å"relevant†. In some cases, â€Å"relevant† and â€Å"suitable† are good synonyms but in this example they are not This article is copyright Higher Score, 2007. It may not be reproduced in whole or in part in any form without permission. www. higherscore. ca [email  protected] ca HIGHER SCORE TOEFL, TOEIC and IELTS clas ses for serious students How to Paraphrase Effectively close in meaning at all. Sentence 3 is a much better paraphrase of sentence 1 because all of the words have the same meaning.The best advice is to follow the â€Å"100% rule† for using synonyms: only use a synonym for a word if you are 100% certain that the new word has 100% the same meaning as the original word. If you are less than 100% certain, keep the same word and use either method two or method three to paraphrase your sentence. Paraphrasing Method 2: Change the Order of Words Changing the word order of a phrase or sentence is usually safer than using synonyms because the words are the same, so the meaning must be the same.However, it is not always easy to decide which words to move or to decide to which position the words should be moved Also, when you move a word you might need to change some other words, add some other words or cut some other words to ensure that the new sentence is grammatically correct. Here a re two suggestions for how to change the word order without making errors: a. If the original sentence has two or more clauses, change the order of the clauses. 1. â€Å"If they have some help, most people can paraphrase effectively.However, practice is important because paraphrasing is difficult. † 2. â€Å"Most people can paraphrase effectively, if they have some help. Paraphrasing is difficult, however, so practice is important. † b. If the original sentence has an adjective and noun, change the adjective into a relative clause. 1. â€Å"Writing essays can be a challenging task. † 2. â€Å"Writing essays can be a task which is challenging. † Paraphrasing Method 3: Use Different Grammar It sounds very difficult to use different grammar, but actually it is easier than changing vocabulary.In addition, if you change the grammar and make an error, usually the reader will understand what you mean. However, if you change the vocabulary and make an error, ofte n the reader will not understand what you mean. So, although changing the grammar has some advantages, it is still not easy and you should practice it as often as possible. Here are two suggestions for how to change the grammar without making errors: This article is copyright Higher Score, 2007. It may not be reproduced in whole or in part in any form without permission. www. higherscore. a [email  protected] ca HIGHER SCORE TOEFL, TOEIC and IELTS classes for serious students How to Paraphrase Effectively a. Change some of the words in the original sentence into different parts of speech (you will often need to change the word order and some other words, too). 1. â€Å"The most effective way to build your English skill is to study regularly. † 2. â€Å"The most effective way of building your English skill is to do studying on a regular basis. † b. If the original sentence is in the active voice, change it to passive or vice versa. 1. To improve English, you should le arn new vocabulary on a daily basis. † 2. â€Å"To improve English, new vocabulary should be learned on a daily basis† Further Practice By using the methods and ideas given in this article, you should be able to improve your paraphrasing skill. In tests like IELTS and TOEFL iBT you will often need to paraphrase quickly, so you need to practice regularly if you are going to get better and faster. Start by practicing each method individually and then begin combining the methods until you are comfortable at using all three of them.If you want to see more examples of paraphrasing, one of the best ideas is to compare two news articles about a current event in two different newspapers. The stories will contain most of the same details, but the sentences will be different. By comparing the sentences and paragraphs you will get more ideas about how to paraphrase and see some real examples. Newspaper websites are often a good place to see two different articles without paying fo r two different newspapers. This article is copyright Higher Score, 2007. It may not be reproduced in whole or in part in any form without permission. ww. higherscore. ca [email  protected] ca HIGHER SCORE TOEFL, TOEIC and IELTS classes for serious students How to Paraphrase Effectively Useful Words The following list defines some of the difficult words used in this article. A synonym is a word or phrase that has almost the same meaning as another word or phrase. For example, ‘smart', ‘clever' and ‘intelligent' are all synonyms because they have almost the same meaning. If two things are equivalent, they are equal or almost equal to each other although they might be in different places.For example, the British ‘prime minister' is equivalent to the United States ‘president' because both the ‘prime minister' and ‘president' are the most powerful politicians in their country. If somebody ensures something, the person makes sure that something is correct or true or OK. For example, if I am going on a trip, I will check my pocket to ensure that I have my passport. A clause is a grammar word that describes part of a sentence that contains a subject and a verb. Most clauses also contain an object or subject complement.Some clauses are ‘reduced' which means that subject (and sometimes the auxiliary verb) are omitted. The phrase part of speech is used to describe the different types of words that are used in English. For example, ‘noun', ‘verb', ‘adjective' and ‘adverb' are four common parts of speech. The expression (and/or) vice versa is used to indicate that the opposite of something which was just mentioned is also true. For example, ‘If the book is on the shelf, put it in the box and vice versa' means ‘If the book is on the shelf, put it in the box and if the book is in the box, put it on the shelf. This article is provided as a free service to all test preparation students by Hi gher Score, Canada’s number one test preparation centre. Students are welcome to send copies of this article to other students who are taking a test. However, this article may not be distributed in any other way without the express written consent of Higher Score. This article is copyright Higher Score, 2007. It may not be reproduced in whole or in part in any form without permission. www. higherscore. ca [email  protected] ca