847 research outputs found
Size-class structure and growth traits of Anastatica hierochuntica L. populations as rainfall indicators in aridlands
AbstractField data verified by green house experiment were used to evaluate the response of Anastatica hierochuntica L. to the amount of rainfall. Field study of the populations was carried out in the runnel and depression microhabitats of gravel and sand sites. Four water treatments, equivalent to 100, 200, 500 and 1000mm rainfall, were used to simulate different levels of water availability. Under 500 and 1000mm rainfall, the size-class structure of A. hierochuntica populations consists of a high proportion of large size-class individuals, while a higher proportion of small size-class individuals was obtained under 100 and 200mm rainfall. The dry skeletons of A. hierochuntica can be used as a “rain gauge” to predict the amount of rain or water received. The dominance of small size-classes (from <1 to 8cm3) gives a prediction of less than 200mm rainfall received. Intermediate size-classes (8–64cm3) characterize habitats with 200–500mm rainfall, while habitats with >500mm rainfall produce large size-classes (>64cm3). Small size-class individuals produced under low amounts of rainfall allocated up to 60% of their phytomass to the reproductive organs. Allocation to reproductive organs decreased with the increase in the amount of rainfall, while allocation to the stem increased in large size-class individuals produced under the highest amount of rainfall (1000mm) reaching 54%. Increased allocation to stem in large-sized individuals favours the hygrochastic seed dispersal role in the plant. The root/shoot ratio decreased with the increase of the individual size-class, i.e. under high rainfall treatments. Higher values of relative growth rate, net assimilation rate and leaf area index were obtained under high water treatments. Conversely, less expanded leaves, i.e. lower specific leaf area, were manifested in the lowest water treatments
Numerical Study for the Behavior of Stainless-Steel Sigma Columns Under Axial Compression Load
This study investigated numerically the behavior of slender austenitic stainless-steel grade EN 1.4420 columns under compression loads. The column has a single lipped Sigma cross section. The finite element model was developed using ABAQUS software, then it was validated by comparing its results against outcomes from a previous experimental study. A parametric study conducted on pin-ended Sigma columns explores the effect of various factors on ultimate strength and failure modes, such as thickness (t) and flange width (B). Results indicate that as the thickness of the column increases, so does its ultimate load capacity. Thicker columns tend to fail due to global buckling. The ultimate capacity increases as the flange width (B) increases from 60 mm to 75 mm, remains constant as the flange width (B) increases from 75 mm to 100 mm, and starts to decrease when the flange width (B) exceeds 100 mm. Comparing carbon steel and austenitic stainless steel Sigma columns, the latter shows a 34% increase in bearing capacity
Randomized ancillary qubit overcomes detector-control and intercept-resend hacking of quantum key distribution
Practical implementations of quantum key distribution (QKD) have been shown
to be subject to various detector side-channel attacks that compromise the
promised unconditional security. Most notable is a general class of attacks
adopting the use of faked-state photons as in the detector-control and, more
broadly, the intercept-resend attacks. In this paper, we present a simple
scheme to overcome such class of attacks: A legitimate user, Bob, uses a
polarization randomizer at his gateway to distort an ancillary polarization of
a phase-encoded photon in a bidirectional QKD configuration. Passing through
the randomizer once on the way to his partner, Alice, and again in the opposite
direction, the polarization qubit of the genuine photon is immune to
randomization. However, the polarization state of a photon from an intruder,
Eve, to Bob is randomized and hence directed to a detector in a different path,
whereupon it triggers an alert. We demonstrate theoretically and experimentally
that, using commercial off-the-shelf detectors, it can be made impossible for
Eve to avoid triggering the alert, no matter what faked-state of light she
uses.Comment: Quantum encryption, bidirectional quantum key distribution, detector
control, intercept and resend attacks, faked state photon
Influencia de distintas fuentes de sílice en las propiedades físicas y mecánicas de materiales derivados del yeso
Gypsum plaster/silica composites prepared by dry blending (0.2-10 %) natural sand, silica fume or silica gel and subsequently hydrated. Their physical and mechanical properties, including normal consistency, setting time, apparent porosity, bulk density and compressive strength, were determined after hydration for 7- and 28-days. The results indicated that adding different forms of silica lowered the bulk density and increased the normal consistency, setting time, apparent porosity and, to some limited extent, compressive strength of the composites. This improvement in properties can be attributed to the existence of silica in the interstitial pores in the hardened plaster matrices. While most of the composites revealed only scant rises in compressive strength, their composition was beneficial in so far as it included either a readily available low-cost constituent (sand) or industrial by-products. Consequently, the formed plaster-silica composites are of economic value, contribute to a cleaner environment by minimizing waste and can be used for applications where high porosity, lightweight units are required or recommended for low-cost buildings.Se prepararon pastas compuestas de yeso y sílice mediante la mezcla en seco de yeso con distintas proporciones (0,2- 10 %) de arena natural, o gel o humo de sílice, procediéndose a continuación a su hidratación. A fin de determinar las propiedades físicas y mecánicas de las pastas, a los 7 y los 28 días de hidratación se hallaron su fluidez, tiempo de fraguado, porosidad aparente, densidad aparente y resistencia a la compresión. Los resultados obtenidos indican que al incorporar las distintas modalidades de sílice a la mezcla, disminuyó la densidad aparente y aumentaron la fluidez, el tiempo de fraguado, la porosidad aparente y, en menor medida, la resistencia a la compresión de las muestras. Se considera que esta mejora de las propiedades del material se debe a la presencia de sílice en los poros intersticiales de las matrices endurecidas de yeso. Aunque la resistencia a la compresión de la mayoría de las pastas ensayadas apenas aumentó, estas se beneficiaron de la presencia en su composición de elementos de bajo coste como la arena o los distintos subproductos industriales utilizados. Puede concluirse, por lo tanto, que los compuestos de yeso y sílice tienen valor económico y contribuyen a mejorar el medioambiente al valorizar residuos. Por otra parte, son apropiados para las aplicaciones en las que se necesitan o recomiendan elementos de alta porosidad y bajo peso, concretamente en las edificaciones bajas
Immunohistochemical Study of Stellate Cells in Patients with Chronic Viral Heptitis C Histopathological study
Background: Chronic hepatitis is defined as liver inflammation that lasts for at least 6 months. The Hepatitis C virus is responsible for 60 to 70% of chronic hepatitis cases; the virus causes continued inflammation that slowly damages the liver, eventually leading to cirrhosis, liver failure, and, in rare cases, liver cancer. Aim of the work: To evaluate the changes in distribution and percentage of alpha-smooth muscle actin-positive hepatic stellate cells and the correlation with the degree of the fibrosis in cirrhotic livers, in patients with HCV chronic hepatitis. Material and methods: 50 hepatic core biopsies selected randomly were received from Histopathology Department at National Hepatology and Tropical Medicine Research Institute and examined for histopathological features using (hematoxylin and eosin), stage of hepatic fibrosis using stellate cell Masson s' trichrome stain, and examined for stellate cell activity using alpha smooth muscle actin (ASMA) immunostaining. Results: The relation between degree of ASMA expression by stellate cells and stage of fibrosis was highly significant with a p value <0.001, also the relation between degree of necroinflammation and degree of ASMA expression by stellate cells was highly significant with a p value <0.001. The relation between degree of necroinflammation and stage of fibrosis was highly significant with a p value <0.001. The relation between age of patient and stage of fibrosis also was statistically significant with a p value =0.012. The relation between age of patient and degree of necroinflammation was statistically significant with a p value =0.017. Conclusion: To summarize from hepatic core biopsies of patients suffering from chronic HCV, the number of active stellate cells was found to be positively associated with stage of hepatic fibrosis
Temporal Analysis and Costs of Ruminant Brucellosis Control Programme in Egypt Between 1999 and 2011
Data for the prevalence of brucellosis in ruminants in Egypt are scarce; recent studies suggest the disease is endemic, with a high prevalence. The aim of this study was to assess the financial costs and the impact of the current control programme on the pattern of brucellosis among ruminants between 1999 and 2011. A univariate binary logistic regression model was used to compare between seropositive proportions for different years for each species. The proportion of seropositive cattle was significantly increased from 2000 to 2004 then significantly decreased from 2005 to 2011. The proportion of seropositive buffalo fluctuated year to year; however, there was a significant increase in 2008 (OR 3.13, 95% CI 2.69–3.66, P < 0.001). There was a decrease in the proportion of seropositive sheep during the study period except in 2001 and 2009 in which there was a significant increase. The proportion of seropositive goats increased in 2000 and 2001, and then decreased from 2002 to 2007. In 2008, there was a significant increase in the seropositive proportion of goats (OR 2.53, 95% CI 2.21–2.90, P < 0.001). The average annual cost for the control programme including testing and compensation was more than US40 million, from which more than 56% for cattle. Further studies are required for the effectiveness of the current control strategies and alternative strategies should be considered. The socio-economic impact of brucellosis and its control measures should be investigated
Non-Invasive Monitoring of Core Body Temperature for Targeted Temperature Management in Post-Cardiac Arrest Care
Importance: Accurate monitoring of core body temperature is integral to targeted temperature management (TTM) following cardiac arrest. However, there are no reliable non-invasive methods for monitoring temperature during TTM. Objectives: We compared the accuracy and precision of a novel non-invasive Zero-Heat-Flux Thermometer (SpotOn™) to a standard invasive esophageal probe in a cohort of patients undergoing TTM post-cardiac arrest. Design, Setting, and Participants: We prospectively enrolled 20 patients undergoing post-cardiac arrest care in the intensive care units at the London Health Sciences Centre in London, Canada. A SpotOn™ probe was applied on each patient\u27s forehead, while an esophageal temperature probe was inserted, and both temperature readings were recorded at 1-min intervals for the duration of TTM. Main outcomes and Measures: We compared the SpotOn™ and esophageal monitors using the Bland–Altman analysis and the Pearson correlation, with accuracy set as a primary outcome. Secondary outcomes included precision and correlation. Bias exceeding 0.1°C and limits of agreement exceeding 0.5°C were considered clinically important. Results: Sixteen (80%) of patients had complete data used in the final analysis. The median (interquartile range) duration of recording was 38 (12–56) h. Compared to the esophageal probe, SpotOn™ had a bias of 0.06 ± 0.45°C and 95% limits of agreement of −0.83 to 0.95°C. The Pearson correlation coefficient was 0.97 (95% confidence interval 0.9663–0.9678), with a two-tailed p \u3c 0.0001. Conclusion and Relevance: The SpotOn™ is an accurate method that may enable non-invasive monitoring of core body temperature during TTM, although its precision is slightly worse than the predefined 0.5°C when compared to invasive esophageal probe
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