Numerical analysis of flow and heat transfer behavior in fin-tube flat-plate solar collector

There has been a lot of concern on the cost of en-ergy during the past two decades. The risk and realityof environmental degradation have become more appar-ent. The growing evidence of environmental problems iscaused by a combination of several factors si…     

Hot topic: Selecting cattle for low residual feed intake did not affect daily methane production but increased methane yield

Reducing enteric methane (CH₄) production and improving feed conversion efficiency of dairy cows is of high importance. Residual feed intake (RFI) is one measure of feed efficiency, with low RFI animals being more efficient in feed conversion. Enteric CH₄ is an important source of digestible energy loss in ruminants and, because research in beef cattle has reported a positive relationship between RFI and daily CH₄ production, we hypothesized that low RFI dairy heifers, which are more feed efficient, would produce less CH₄/d. We measured the daily methane production (g of CH₄/d), methane yield [g of CH₄/kg of dry matter intake (DMI)], and CH₄ per kilogram of body weight (BW) gain for 56 heifers (20–22 mo old) in a 2 × 2 factorial arrangement: factors included 2 breeds (Holstein-Friesian and Jersey; n = 28/breed), with equal numbers of animals previously determined as being either high [+2.0 kg of dry matter (DM)/d] or low RFI (?2.1 kg of DM/d; n = 28/RFI category). All heifers were commingled and offered unrestricted access to the same diet of dried alfalfa cubes. Between RFI categories, heifers did not differ in BW or BW gain but low RFI heifers had 9.3 and 10.6% lower DMI and DMI/kg of BW, respectively, than high RFI heifers. Similarly, RFI category did not affect CH₄/d or CH₄/kg of BWg, but CH₄/kg of DMI was higher in low RFI heifers because of their lower DMI. These results might reflect more complete digestion of ingested feed in the more efficient, low RFI heifers, consistent with previous reports of greater apparent digestibility of organic matter. Holstein-Friesian heifers were heavier and consumed more total DM than Jersey heifers, but breed did not affect DMI/kg of BW or BWg. Jersey heifers produced less CH₄/d, but not CH₄/kg of DMI or CH₄/kg of BWg. We detected no interaction between breed and RFI category in any of the variables measured. In conclusion, differences in RFI in dairy heifers did not affect daily CH₄ production (g/d); however, low RFI heifers had a greater CH₄ yield (g/kg of DMI) on a high forage diet.     

Chemopreventive potential of the tannase-mediated biotransformation of green tea

Green tea (Camellia sinensis) is one of the most widely consumed beverages in the world. The cancer chemopreventive qualities of green tea have been well documented. Epigallocatechin gallate (EGCG) is often described as the most potently chemopreventive green tea catechin; however, the low bioavailability of EGCG is a limiting factor for its biological effect. Thus, the aim of this work was to test the chemopreventive potential of green tea extract and EGCG after tannase-mediated hydrolysis. The results showed that the biotransformed compounds retained most of the beneficial properties of the original compounds, and some beneficial properties were improved in the biotransformed compounds. Biotransformation of EGCG decreased its toxicity without affecting its antiproliferative effects. Furthermore, human cells gene expression profiling showed that the biotransformed compounds modulated the expression of several genes related to carcinogenesis. These results demonstrate the benefits of the biotechnological modification of natural food molecules, allowing the improvement of the nutraceutical potential of a beverage as green tea.     

Enhanced tuberculosis identification through 1-month follow-up of smear-negative tuberculosis suspects

背景:在几内亚比绍共和国比绍实施的Bandim卫生项目.目的:对最初就诊时已被排除患有结核病的既往结核病可疑者进行结核病筛查.设计:这是一个队列随访研究,对初次就诊时痰涂片检查为阴性的“结核病阴性可疑者”在其初次就诊后1个月内进行结核病症状筛查,并将有症状者转诊接受临床复查和HIV检测.结果:2007年的10个月期间共登记结核病可疑者428例,其中80％(343例)为痰涂片阴性,而21例涂片阴性者被诊断为涂阴肺结核患者.在余下的322例结核病阴性可疑者中,对212例进行了随访,并在初诊后1个月内对有症状者进行了复查.在接受随访的患者中,89例(42％)仍然有症状；经复查痰涂片和胸部X线,5例被确诊为患有结核病.44例有症状且接受HIV检测的患者中,39％(17例)为HIV感染者.322例结核病阴性可疑者中,13例(4％)在随访前已经死亡.结论:很大一部分结核病阴性患者在初诊后一个月仍有症状.几例结核病患者初诊时未被诊断,结核病患者的HIV感染率较高.结核病阴性可疑者死亡率较高,这就需要结核病和艾滋病防治规划均应提高对此问题的重视程度.     

Report from HotMobile 2009

HotMobile is SIGMOBILE's premier venue for early-stage research. Recurring themes from this year's workshop were social interactions, location awareness, and user privacy.     

Postnephrectomy arteriovenous fistula

Dissociation of Ca2+ from human interstitial collagenase induced either by chelation with EGTA or by dilution resulted in loss of enzyme activity, a red shifted emission maximum from 334 to 340 nm and quenching of protein fluorescence by 10% at 340 nm. Circular dichroism indicated that secondary structure was unaffected by EGTA. Ca2+ binding to the EGTA-treated enzyme as assessed by fluorescence was cooperative (Hill coefficient, 2.9; 50% saturation at 0.4 mM Ca2+). The dependence of catalytic activity on [Ca2+] was also cooperative (Hill coefficient, 1.7-2.0; midpoint [Ca2+], 0.2 mM). The Ca2+-reconstituted protein was indistinguishable from the untreated enzyme by activity and fluorescence measurements. These results demonstrate that removal of Ca2+ from full-length collagenase generates a catalytically incompetent, partially unfolded state with native secondary structure but altered tertiary structure characterized by exposure of at least one tryptophyl residue to a more polar environment.     

Human group C rotavirus in children with diarrhea in the Federal District, Brazil

BACKGROUND: A family history of atopy is a poor predictor of sensitization to inhalant allergens and allergic disease during childhood. We recently identified early sensitization to food allergens, especially hen's egg, as a valuable predictor of subsequent sensitization to inhalant allergens. OBJECTIVE: (1) Whether prediction will be improved by in vitro allergy tests at 1 year of age in combination with family history and medical history data. (2) Comparison with the capacities of in vitro tests to predict sensitization to aeroallergens. METHODS: Of an observational birth cohort study (MAS) 49 children who were sensitized to inhalant allergens at 5 years of age and 116 non-sensitized controls were included in the present study. For the prediction of sensitization to inhalant allergens the following prognostic factors were evaluated: atopic family history (FH), atopic dermatitis (AD) during the first year of life, two in vitro allergy tests for specific IgE to common food allergens at 1 year of age (fx5 [Pharmacia] and single allergen specific tests (sIgE) for four allergens) and 'high' total serum IgE, defined by three different cut off points. RESULTS: The combination of medical history data and laboratory tests resulted in the best predictive discrimination. The positive predictive values (PPV) were higher if sensitization to food was detected by single allergen specific tests (PPV: 66%/75%/100% corresponding to the three evaluated risk groups) than by the qualitative fx5 (PPV: 46%/65%/100%). The negative predictive values were equal for both tests (69 and 92% for the two low risk groups). High total serum IgE had low predictive capacity. CONCLUSION: During infancy the prediction of sensitization to inhalant allergens should be based on medical history data and allergy tests determining sensitization to food allergens. The in vitro tests improve the predictive discrimination, but the individual risk profile of the child must be considered for a reliable and valid prediction.     

The central pixel of the MAGIC telescope for optical observations

The MAGIC telescope has been designed for the observation of Cherenkov light generated in Extensive Air Showers initiated by cosmic particles. However, its 17 m diameter mirror and optical design makes the telescope suitable for direct optical observations as well. In this paper, we report about the development of a system based on the use of a dedicated photo-multiplier (PMT) for optical observations. This PMT is installed in the centre of the MAGIC camera (the so-called central pixel). An electro-to-optical system has been developed in order to transmit the PMT output signal by an optical fibre to the counting room, where it is digitized and stored for off-line analysis. The performance of the system using the optical pulsation of the Crab nebula as calibration source is presented. The time required for a 5σ detection of the Crab pulsar in the optical band is less than 20 s. The central pixel will be mainly used to perform simultaneous observations of the Crab pulsar both in the optical and γ-ray regimes. It will also allow for periodic testing of the precision of the MAGIC timing system using the Crab rotational optical pulses as a very precise timing reference.     

Preliminary survey of a school health program implementation in Guinea

The Sectorial Adjustment Education Program implemented in Guinea by the Ministry of Pre-University Education in 1995 includes health-related measures. An important part is the fight against parasitosis and in particular against intestinal helminth infection which has been shown to impair cognitive function in school children. In order to obtain data for this purpose, a survey was carried out in 7 subprefectures across the country. A total of 1,649 children were examined to determine the prevalence in each school of macroscopic hematuria-related schistosomiasis and of various intestinal helminthiasis in stools. In 1468 of these children blood tests were also made to measure hemoglobin levels and detect malarial hematozoons. Overall prevalence rates were 60.0% for soil-transmitted nematodes, 9.1% for urinary schistosomiasis, 57.6% for blood plasmodium, and 57.0% for anemia. Hemoglobin levels were lower in children presenting plasmodium, multiple parasitic infection, and high ankylostoma burdens. Prevalence rates varied widely between regions indicating differences in therapeutic measures. In two villages more than 200 children not attending school who had been informed by school children were treated. This word-of-mouth effect shows that school health programs are also useful to reach children outside the school health system.     

Tabu Search Heuristic for Point-Feature Cartographic Label Placement

The generation of better label placement configurations in maps is a problem that comes up in automated cartographic production. The objective of a good label placement is to display the geographic position of the features with their corresponding label in a clear and harmonious fashion, following accepted cartographic conventions. In this work, we have approached this problem from a combinatorial optimization point of view, and our research consisted of the evaluation of the tabu search (TS) heuristic applied to cartographic label placement. When compared, in real and random test cases, with techniques such as simulated annealing and genetic algorithm (GA), TS has proven to be an efficient choice, with the best performance in quality. We concluded that TS is a recommended method to solve cartographic label placement problem of point features, due to its simplicity, practicality, efficiency and good performance along with its ability to generate quality solutions in acceptable computational time.