Fifty years of sustained investment in research and development has left the Australian cotton industry well placed to manage nitrogen（N） fertiliser. The average production in the Australian cotton industry today is...Fifty years of sustained investment in research and development has left the Australian cotton industry well placed to manage nitrogen（N） fertiliser. The average production in the Australian cotton industry today is greater than two tonnes of lint per hectare due to improved plant genetics and crop management. However, this average yield is well below the yield that would be expected from the amount of N fertiliser used. It is clear from the recent studies that across all growing regions, conversion of fertiliser N into lint is not uniformly occurring at application rates greater than 200-240 kg·hm;of N. This indicates that factors other than N availability are limiting yield, and that the observed nitrogen fertiliser use efficiency（NFUE） values may be caused by subsoil constraints such as sodicity and compaction. There is a need to investigate the impact of subsoil constraints on yield and NFUE.Gains in NFUE will be made through improved N fertiliser application timing, better targeting the amount of fertiliser applied for the expected yield, and improved soil N management. There is also a need to improve the ability and confidence of growers to estimate the contribution of soil N mineralisation to the crop N budget. Many Australian studies including data that could theoretically be collated in a meta-analysis suggest relative NFUE values as a function of irrigation technique; however, with the extensive list of uncontrolled variables and few studies using non-furrow irrigation, this would be a poor substitute for a single field-based study directly measuring their efficacies. In irrigated cotton, a re-examination of optimal NFUE is due because of the availability of new varieties and the potential management and long-term soil resilience implications of the continued removal of mineralised soil N suggested by high NFUE values. NFUE critical limits still need to be derived for dryland systems.展开更多
Thermodynamic equations of state(EOS)for crystalline solids describe material behaviors under changes in pressure,volume,entropy and temperature,making them fundamental to scientific research in a wide range of fields...Thermodynamic equations of state(EOS)for crystalline solids describe material behaviors under changes in pressure,volume,entropy and temperature,making them fundamental to scientific research in a wide range of fields including geophysics,energy storage and development of novel materials.Despite over a century of theoretical development and experimental testing of energy–volume(E–V)EOS for solids,there is still a lack of consensus with regard to which equation is indeed optimal,as well as to what metric is most appropriate for making this judgment.In this study,several metrics were used to evaluate quality of fit for 8 different EOS across 87 elements and over 100 compounds which appear in the literature.Our findings do not indicate a clear“best”EOS,but we identify three which consistently perform well relative to the rest of the set.Furthermore,we find that for the aggregate data set,the RMSrD is not strongly correlated with the nature of the compound,e.g.,whether it is a metal,insulator,or semiconductor,nor the bulk modulus for any of the EOS,indicating that a single equation can be used across a broad range of classes of materials.展开更多
Band structures for electrons,phonons,and other quasiparticles are often an important aspect of describing the physical properties of periodic solids.Most commonly,energy bands are computed along a one-dimensional pat...Band structures for electrons,phonons,and other quasiparticles are often an important aspect of describing the physical properties of periodic solids.Most commonly,energy bands are computed along a one-dimensional path of high-symmetry points and line segments in reciprocal space(the“k-path”),which are assumed to pass through important features of the dispersion landscape.However,existing methods for choosing this path rely on tabulated lists of high-symmetry points and line segments in the first Brillouin zone,determined using different symmetry criteria and unit cell conventions.Here we present a new“on-the-fly”symmetry-based approach to obtaining paths in reciprocal space that attempts to address the previous limitations of these conventions.Given a unit cell of a magnetic or nonmagnetic periodic solid,the site symmetry groups of points and line segments in the irreducible Brillouin zone are obtained from the total space group.The elements in these groups are used alongside general and maximally inclusive high-symmetry criteria to choose segments for the final k-path.A smooth path connecting each segment is obtained using graph theory.This new framework not only allows for increased flexibility and user convenience but also identifies notable overlooked features in certain electronic band structures.In addition,a more intelligent and efficient method for analyzing magnetic materials is also enabled through proper accommodation of magnetic symmetry.展开更多
The aim of the current study was to examine the prevalence of HIV, past six-month illicit drug use, and risk behaviors among a population of heavy drug users living in an urban setting. Although many studies investiga...The aim of the current study was to examine the prevalence of HIV, past six-month illicit drug use, and risk behaviors among a population of heavy drug users living in an urban setting. Although many studies investigate substance use, sex-risk behavior, and HIV by race and gender, no studies have examined these variables simultaneously. The current study seeks to fill this gap in the literature by exploring HIV prevalence among a predominantly heterosexual sample of recent substance users by injection drug use (IDU) status, race, and sex. Baseline data from the Baltimore site of the NEURO-HIV epidemiologic study was used in this study. This study examines neuropsychological and social-behavioral risk factors of HIV, hepatitis A, hepatitis B, and hepatitis C among both injection and non-injection drug users. Descriptive statistics and chi-square statistics were used in data analyses. Blood and urine samples were obtained to test for the presence of recent drug use, viral hepatitis, HIV, and other sexually transmitted diseases (STDs). Findings presented here have several important implications for HIV prevention and care among substance users. Intervention programs that incorporate substance use treatment in addition to HIV education, particularly with respect to substance use and sex risk behavior are imperative.展开更多
A hybrid model is proposed in this study to predict rectal tumour response during radiotherapy treatment. As the oxygen partial pressure distribution (pO<sub>2</sub>) is a data which is naturally represent...A hybrid model is proposed in this study to predict rectal tumour response during radiotherapy treatment. As the oxygen partial pressure distribution (pO<sub>2</sub>) is a data which is naturally represented at the microscopic scale, we firstly estimate the optimal pO<sub>2</sub> distribution using both a diffusion equation and a discrete multi-scale model (that we proposed in a previous study). The aim is to use the effectiveness in algorithmic complexity of the discrete model and its multi-scale aspect in this work to estimate biological information at cellular scale and then construct them at macroscopic scale. Secondly, the obtained pO<sub>2</sub> distribution results are used as an input of a biomechanical model in order to simulate tumour volume evolution during radiotherapy. FDG PET images of 21 rectal cancer patients undergoing radiotherapy are used to simulate the tumour evolution during the treatment. The simulated results using the proposed hybride model, allow the interpretation of tumour aggressiveness.展开更多
基金funded by the Australian Government Department of Agriculture and Water Resourcesthe Cotton Research and Development Corporation's Rural Research and Development for Profit Project "More profit from nitrogen:enhancing the nutrient use efficiency of intensive cropping and pasture systems"funded by the Cotton Research and Development Corporation's PhD scholarship
文摘Fifty years of sustained investment in research and development has left the Australian cotton industry well placed to manage nitrogen（N） fertiliser. The average production in the Australian cotton industry today is greater than two tonnes of lint per hectare due to improved plant genetics and crop management. However, this average yield is well below the yield that would be expected from the amount of N fertiliser used. It is clear from the recent studies that across all growing regions, conversion of fertiliser N into lint is not uniformly occurring at application rates greater than 200-240 kg·hm;of N. This indicates that factors other than N availability are limiting yield, and that the observed nitrogen fertiliser use efficiency（NFUE） values may be caused by subsoil constraints such as sodicity and compaction. There is a need to investigate the impact of subsoil constraints on yield and NFUE.Gains in NFUE will be made through improved N fertiliser application timing, better targeting the amount of fertiliser applied for the expected yield, and improved soil N management. There is also a need to improve the ability and confidence of growers to estimate the contribution of soil N mineralisation to the crop N budget. Many Australian studies including data that could theoretically be collated in a meta-analysis suggest relative NFUE values as a function of irrigation technique; however, with the extensive list of uncontrolled variables and few studies using non-furrow irrigation, this would be a poor substitute for a single field-based study directly measuring their efficacies. In irrigated cotton, a re-examination of optimal NFUE is due because of the availability of new varieties and the potential management and long-term soil resilience implications of the continued removal of mineralised soil N suggested by high NFUE values. NFUE critical limits still need to be derived for dryland systems.
基金Intellectually led by the Center for Next Generation Materials by Design,an Energy Frontier Research Center funded by the U.S.Department of Energy,Office of Science,Basic Energy Sciences under Awards DE-AC02-05CH11231 and DE-AC36-089028308.
文摘Thermodynamic equations of state(EOS)for crystalline solids describe material behaviors under changes in pressure,volume,entropy and temperature,making them fundamental to scientific research in a wide range of fields including geophysics,energy storage and development of novel materials.Despite over a century of theoretical development and experimental testing of energy–volume(E–V)EOS for solids,there is still a lack of consensus with regard to which equation is indeed optimal,as well as to what metric is most appropriate for making this judgment.In this study,several metrics were used to evaluate quality of fit for 8 different EOS across 87 elements and over 100 compounds which appear in the literature.Our findings do not indicate a clear“best”EOS,but we identify three which consistently perform well relative to the rest of the set.Furthermore,we find that for the aggregate data set,the RMSrD is not strongly correlated with the nature of the compound,e.g.,whether it is a metal,insulator,or semiconductor,nor the bulk modulus for any of the EOS,indicating that a single equation can be used across a broad range of classes of materials.
基金The authors acknowledge support by the U.S.Department of Energy,Office of Science,Office of Basic Energy Sciences,Materials Sciences and Engineering Division under Contract No.DE-AC02-05-CH11231(Materials Project program KC23MP)This research used resources of the National Energy Research Scientific Computing Center(NERSC),a U.S.Department of Energy Office of Science User Facility operated under Contract No.DE-AC02-05CH11231.
文摘Band structures for electrons,phonons,and other quasiparticles are often an important aspect of describing the physical properties of periodic solids.Most commonly,energy bands are computed along a one-dimensional path of high-symmetry points and line segments in reciprocal space(the“k-path”),which are assumed to pass through important features of the dispersion landscape.However,existing methods for choosing this path rely on tabulated lists of high-symmetry points and line segments in the first Brillouin zone,determined using different symmetry criteria and unit cell conventions.Here we present a new“on-the-fly”symmetry-based approach to obtaining paths in reciprocal space that attempts to address the previous limitations of these conventions.Given a unit cell of a magnetic or nonmagnetic periodic solid,the site symmetry groups of points and line segments in the irreducible Brillouin zone are obtained from the total space group.The elements in these groups are used alongside general and maximally inclusive high-symmetry criteria to choose segments for the final k-path.A smooth path connecting each segment is obtained using graph theory.This new framework not only allows for increased flexibility and user convenience but also identifies notable overlooked features in certain electronic band structures.In addition,a more intelligent and efficient method for analyzing magnetic materials is also enabled through proper accommodation of magnetic symmetry.
文摘The aim of the current study was to examine the prevalence of HIV, past six-month illicit drug use, and risk behaviors among a population of heavy drug users living in an urban setting. Although many studies investigate substance use, sex-risk behavior, and HIV by race and gender, no studies have examined these variables simultaneously. The current study seeks to fill this gap in the literature by exploring HIV prevalence among a predominantly heterosexual sample of recent substance users by injection drug use (IDU) status, race, and sex. Baseline data from the Baltimore site of the NEURO-HIV epidemiologic study was used in this study. This study examines neuropsychological and social-behavioral risk factors of HIV, hepatitis A, hepatitis B, and hepatitis C among both injection and non-injection drug users. Descriptive statistics and chi-square statistics were used in data analyses. Blood and urine samples were obtained to test for the presence of recent drug use, viral hepatitis, HIV, and other sexually transmitted diseases (STDs). Findings presented here have several important implications for HIV prevention and care among substance users. Intervention programs that incorporate substance use treatment in addition to HIV education, particularly with respect to substance use and sex risk behavior are imperative.
文摘A hybrid model is proposed in this study to predict rectal tumour response during radiotherapy treatment. As the oxygen partial pressure distribution (pO<sub>2</sub>) is a data which is naturally represented at the microscopic scale, we firstly estimate the optimal pO<sub>2</sub> distribution using both a diffusion equation and a discrete multi-scale model (that we proposed in a previous study). The aim is to use the effectiveness in algorithmic complexity of the discrete model and its multi-scale aspect in this work to estimate biological information at cellular scale and then construct them at macroscopic scale. Secondly, the obtained pO<sub>2</sub> distribution results are used as an input of a biomechanical model in order to simulate tumour volume evolution during radiotherapy. FDG PET images of 21 rectal cancer patients undergoing radiotherapy are used to simulate the tumour evolution during the treatment. The simulated results using the proposed hybride model, allow the interpretation of tumour aggressiveness.
