Equivalence of two approaches for the inhomogeneous density in the canonical ensemble

In this article we show that the inhomogeneous density obtained from a density-functional theory of classical fluids in the canonical ensemble (CE), recently presented by White et al [Phys. Rev. Lett. 84 (2000) 1220], is equivalent to first order to the result of the series expansion of the CE inhomogeneous density introduced by Gonzalez et al [Phys. Rev. Lett. 79 (1997) 2466].Comment: 6 pages, RevTe

Gallavotti-Cohen theorem, Chaotic Hypothesis and the zero-noise limit

The Fluctuation Relation for a stationary state, kept at constant energy by a deterministic thermostat - the Gallavotti-Cohen Theorem -- relies on the ergodic properties of the system considered. We show that when perturbed by an energy-conserving random noise, the relation follows trivially for any system at finite noise amplitude. The time needed to achieve stationarity may stay finite as the noise tends to zero, or it may diverge. In the former case the Gallavotti-Cohen result is recovered, while in the latter case, the crossover time may be computed from the action of `instanton' orbits that bridge attractors and repellors. We suggest that the `Chaotic Hypothesis' of Gallavotti can thus be reformulated as a matter of stochastic stability of the measure in trajectory space. In this form this hypothesis may be directly tested

Cost Implications of the Prevalence of HIV/AIDS on the Economic Development of Nigeria.

HIV/AIDS emerged in the last three decades as visible threat to health and the socio-economic conditions of developing countries including Nigeria. Against this background, this study sought to determine the cost implications of the prevalence of HIV/AIDs on the economic development of Nigeria. The study adopted mainly qualitative approach sourced from National Bureau of Statistics-(NBS) and Central Bank of Nigeria-(CBN) statistical Bulletin respectively for analysis. Findings seem to support claims that the incidence of HIV/AIDS exert serious negative influences on the economic growth of Nigeria. This is due to the fact that HIV/AIDS reduces to a large extent the proportion of the working population with its huge corresponding cost implications, which in turn affect economic resources in the country. The policy interventions strategies recommended for stemming the scourge of HIV/AIDS include; prevention of new infections, cost reduction of treatments for patients, positive adjustments of patients to employment environment and development of activities like pycho-educational programme to motivate and foster HIV/AIDS prevention and management  behaviours among the Nigeria populace especially the youth. Keywords: Cost, Economic Growth; Employment, HIV/AIDS, Productivit

Cost Implications of the Prevalence of HIV/AIDS on the Economic Development of Nigeria

HIV/AIDS emerged in the last three decades as visible threat to health and the socio-economic conditions of developing countries including Nigeria. Against this background, this study sought to determine the cost implications of the prevalence of HIV/AIDs on the economic development of Nigeria. The study adopted mainly qualitative approach sourced from National Bureau of Statistics-(NBS) and Central Bank of Nigeria-(CBN) statistical Bulletin respectively for analysis. Findings seem to support claims that the incidence of HIV/AIDS exert serious negative influences on the economic growth of Nigeria. This is due to the fact that HIV/AIDS reduces to a large extent the proportion of the working population with its huge corresponding cost implications, which in turn affect economic resources in the country. The policy interventions strategies recommended for stemming the scourge of HIV/AIDS include; prevention of new infections, cost reduction of treatments for patients, positive adjustments of patients to employment environment and development of activities like pycho-educational programme to motivate and foster HIV/AIDS prevention and management  behaviours among the Nigeria populace especially the youth. Keywords: Cost, Economic Growth; Employment, HIV/AIDS, Productivit

Differential effect of selected methylxanthine derivatives on radiosensitization of lung carcinoma cells

Aim: Using caffeine as a reference derivative, this study was performed to investigate how other methylxanthine derivatives, theophylline, 3-isobutyl-methylxanthine and 1,3-dipropyl-7-methylxanthine, sensitize cells to radiation by modifying cell cycle checkpoints and inducing the apoptotic response. The effect of the methylxanthine derivatives was studied in response to gamma and ultraviolet radiation in a human large cell lung carcinoma cell line, null for p53, a normal lung epithelial cell line and the large cell lung carcinoma cell line stably transfected with p53. Methods: Effects of theophylline, 3-isobutyl-methylxanthine and 1,3-dipropyl 7-methylxanthine on cell-radiosensitization in comparison to caffeine tested by clonogenic survival assay, MTT assay, ELISA based apoptotic assay, flow cytometry, caspase-3 activity, TUNEL assay, and western blot analysis. Results: All the derivatives, except 3-isobutyl-methylxanthine, increased tumor cell sensitization to radiation by inducing apoptosis in the p53-null lung cancer cell line. The pattern of cell cycle progression revealed that these derivatives increased the number of cells in G1 phase by abrogating the G2/M checkpoint, directing the cells to apoptose through a p53-independent mechanism. In contrast, 3-isobutyl-methylxanthine was more potent than the other derivatives in radiosensitization of normal lung epithelial cells and the lung carcinoma cells stably transfected with wild-type p53. IBMX increased p53 protein level more than caffeine in lung carcinoma cells stably transfected with wild-type p53. Conclusion: Our results suggest that 3-isobutyl-methylxanthine might function through a p53-dependent mechanism.Цель: провести cравнительный анализ влияния кофеина и других производных метилксантина (тиофилин (ТФ), 3-изобутил-метилксантин (3-ИБМК), 1-3-дипропил-7-метилксантин (1-3-ДП-7МК)) на радиосенсибилизацию клеток крупноклеточной карциномы легкого человека, не содержащих гена p53, нормальных эпителиальных клеток легкого и круп- ноклеточной карциномы легкого, стабильно трансфецированной геном p53. Изучали влияние производных метил­ксантина на реакцию клеток на гамма- и ультрафиолетовое облучение. Методы: радиосенсибилизацию клеток под действием кофеина, ТФ, 3-ИБМК и 1-3-ДП-7МК исследовали при помощи клоногенного анализа, МТТ-анализа, иммунофермент- ного метода, адаптированного для выявления апоптотических клеток, проточной цитометрии, спектрофотометрического метода определения каспазы-3, ТUNEL-метода, а также иммуноблоттинга. Результаты: все производные метилксан- тина, за исключением 3-ИБМК, повышали чувствительность опухолевых клеток к радиации путем индукции апоптоза клеток рака легкого, лишенных гена p53. Эти производные повышали число клеток в G1 фазе путем блока перехода G2/M клеточного цикла, вызывали апоптоз по p53-независимому механизму. В то же время 3-ИБМК проявил себя как более мощный радиосенсибилизатор нормальных эпителиальных клеток легкого, стабильно трансфецированных диким типом гена p53. 3-ИБМК повышал уровень p53 белка в большей степени, чем кофеин в клетках карциномы легкого, стабильно трансфецированных диким типом гена p53. Выводы: результаты позволяют предположить, что действие 3-ИБМК осу- ществляется по p53-зависимому пути

Cross-sectional analyses of a national database to determine if superior genetic merit translates to superior dairy cow performance

peer-reviewedVarious studies have validated that genetic divergence in dairy cattle translates to phenotypic differences; nonetheless, many studies that consider the breeding goal, or associated traits, have generally been small scale, often undertaken in controlled environments, and they lack consideration for the entire suite of traits included in the breeding goal. Therefore, the objective of the present study was to fill this void, and in doing so, provide producers with confidence that the estimated breeding values (EBV) included in the breeding goal do (or otherwise) translate to desired changes in performance among commercial cattle; an additional outcome of such an approach is the identification of potential areas for improvements. Performance data on 536,923 Irish dairy cows (and their progeny) from 13,399 commercial spring-calving herds were used. Association analyses between the cow's EBV of each trait included in the Irish total merit index for dairy cows (which was derived before her own performance data accumulated) and her subsequent performance were undertaken using linear mixed models; milk production, fertility, calving, maintenance (i.e., liveweight), beef, health, and management traits were all considered in the analyses. Results confirm that excelling in EBV for individual traits, as well as on the total merit index, generally delivers superior phenotypic performance; examples of the improved performance for genetically elite animals include a greater yield and concentration of both milk fat and milk protein, despite a lower milk volume, superior reproductive performance, better survival, improved udder and hoof health, lighter cows, and fewer calving complications; all these gains were achieved with minimal to no effect on the beef merit of the dairy cow's progeny. The associated phenotypic change in each performance trait per unit change in its respective EBV was largely in line with the direction and magnitude of expectation, the exception being for calving interval. Per unit change in calving interval EBV, the direction of phenotypic response was as anticipated but the magnitude of the response was only half of what was expected. Despite the deviation from expectation between the calving interval EBV and its associated phenotype, a superior total merit index or a superior fertility EBV was indeed associated with an improvement in all detailed fertility performance phenotypes investigated. Results substantiate that breeding is a sustainable strategy of improving phenotypic performance in commercial dairy cattle and, by extension, profit

Choice of artificial insemination beef bulls used to mate with female dairy cattle

peer-reviewedUnderstanding the preferences of dairy cattle producers when selecting beef bulls for mating can help inform beef breeding programs as well as provide default parameters in mating advice systems. The objective of the present study was to characterize the genetic merit of beef artificial insemination (AI) bulls used in dairy herds, with particular reference to traits associated with both calving performance and carcass merit. The characteristics of the beef AI bulls used were compared with those of the dairy AI bulls used on the same farms. A total of 2,733,524 AI records from 928,437 females in 5,967 Irish dairy herds were used. Sire predicted transmitting ability (PTA) values and associated reliability values for calving performance and carcass traits based on national genetic evaluations from prior to the insemination were used. Fixed effects models were used to relate both genetic merit and the associated reliability of the dairy and beef bulls used on the farm with herd size, the extent of Holstein-Friesian × Jersey crossbreeding adopted by the herd, whether the herd used a technician insemination service or do-ityourself, and the parity of the female mated. The mean direct calving difficulty PTA of the beef bulls used was 1.85 units higher than that of the dairy bulls but with over 3 times greater variability in the beef bulls. This 1.85 units equates biologically to an expectation of 1.85 more dystocia events per 100 dairy cows mated in the beef × dairy matings. The mean calving difficulty PTA of the dairy AI bulls used reduced with increasing herd size, whereas the mean calving difficulty PTA of the beef AI bulls used increased as herd size increased from 75 cows or fewer to 155 cows; the largest herds (>155 cows) used notably easier-calving beef bulls, albeit the calving difficulty PTA of the beef bulls was 3.33 units versus 1.67 units for the dairy bulls used in these herds. Although we found a general tendency for larger herds to use dairy AI bulls with lower reliability, this trend was not obvious in the beef AI bulls used. Irrespective of whether dairy or beef AI bulls were considered, herds that operated more extensive Holstein-Friesian × Jersey crossbreeding (i.e., more than 50% crossbred cows) used, on average, easier calving, shorter gestationlength bulls with lighter expected progeny carcasses of poorer conformation. Mean calving difficulty PTA of dairy bulls used increased from 1.39 in heifers to 1.79 in first-parity cows and to 1.82 in second-parity cows, remaining relatively constant thereafter. In contrast, the mean calving difficulty PTA of the beef bulls used increased consistently with cow parity. Results from the present study demonstrate a clear difference in the mean acceptable genetic merit of beef AI bulls relative to dairy AI bulls but also indicates that these acceptable limits vary by herd characteristics

The liquid-vapor interface of an ionic fluid

We investigate the liquid-vapor interface of the restricted primitive model (RPM) for an ionic fluid using a density-functional approximation based on correlation functions of the homogeneous fluid as obtained from the mean-spherical approximation (MSA). In the limit of a homogeneous fluid our approach yields the well-known MSA (energy) equation of state. The ionic interfacial density profiles, which for the RPM are identical for both species, have a shape similar to those of simple atomic fluids in that the decay towards the bulk values is more rapid on the vapor side than on the liquid side. This is the opposite asymmetry of the decay to that found in earlier calculations for the RPM based on a square-gradient theory. The width of the interface is, for a wide range of temperatures, approximately four times the second moment correlation length of the liquid phase. We discuss the magnitude and temperature dependence of the surface tension, and argue that for temperatures near the triple point the ratio of the dimensionless surface tension and critical temperature is much smaller for the RPM than for simple atomic fluids.Comment: 6 postscript figures, submitted to Phys. Rev.

Childhood and the politics of scale: Descaling children's geographies?

This is the post-print version of the final published paper that is available from the link below. Copyright @ 2008 SAGE Publications.The past decade has witnessed a resurgence of interest in the geographies of children's lives, and particularly in engaging the voices and activities of young people in geographical research. Much of this growing body of scholarship is characterized by a very parochial locus of interest — the neighbourhood, playground, shopping mall or journey to school. In this paper I explore some of the roots of children's geographies' preoccupation with the micro-scale and argue that it limits the relevance of research, both politically and to other areas of geography. In order to widen the scope of children's geographies, some scholars have engaged with developments in the theorization of scale. I present these arguments but also point to their limitations. As an alternative, I propose that the notion of a flat ontology might help overcome some difficulties around scalar thinking, and provide a useful means of conceptualizing sociospatiality in material and non-hierarchical terms. Bringing together flat ontology and work in children's geographies on embodied subjectivity, I argue that it is important to examine the nature and limits of children's spaces of perception and action. While these spaces are not simply `local', they seldom afford children opportunities to comment on, or intervene in, the events, processes and decisions that shape their own lives. The implications for the substance and method of children's geographies and for geographical work on scale are considered