Combinations of weak classifiers

To obtain classification systems with both good generalization performance and efficiency in space and time, we propose a learning method based on combinations of weak classifiers, where weak classifiers are linear classifiers (perceptrons) which can do a little better than making random guesses. A randomized algorithm is proposed to find the weak classifiers. They are then combined through a majority vote. As demonstrated through systematic experiments, the method developed is able to obtain combinations of weak classifiers with good generalization performance and a fast training time on a variety of test problems and real applications. Theoretical analysis on one of the test problems investigated in our experiments provides insights on when and why the proposed method works. In particular, when the strength of weak classifiers is properly chosen, combinations of weak classifiers can achieve a good generalization performance with polynomial space- and time-complexity.

Saponins isolated from Asparagus induce apoptosis in human hepatoma cell line HepG2 through a mitochondrial-mediated pathway

OBJECTIVE

Many scientific studies have shown that Asparagus officinalis has an antitumour effect and enhances human immunity, but the active components and the antitumour mechanisms are unclear. We investigated the effects of saponins isolated from Asparagus on proliferation and apoptosis in the human hepatoma cell line HepG2.

METHODS

HepG2 cells were treated with varying concentrations of Asparagus saponins at various times. Using mtt and flow cytometry assays, we evaluated the effects of Asparagus saponins on the growth and apoptosis of HepG2 cells. Transmission electron microscopy was used to observe the morphology of cell apoptosis. Confocal laser scanning microscopy was used to analyze intracellular calcium ion concentration, mitochondrial permeability transition pore (mptp), and mitochondrial membrane potential (mmp). Spectrophotometry was applied to quantify the activity of caspase-9 and caspase-3. Flow cytometry was used to investigate the levels of reactive oxygen species (ros) and pH, and the expressions of Bcl2, Bax, CytC, and caspase-3, in HepG2 cells.

RESULTS

Asparagus saponins inhibited the growth of HepG2 cells in a dose-dependent manner. The median inhibitory concentration (IC(50)) was 101.15 mg/L at 72 hours. The apoptosis morphology at 72 hours of treatment was obvious, showing cell protuberance, concentrated cytoplasm, and apoptotic bodies. The apoptotic rates at 72 hours were 30.9%, 51.7%, and 62.1% (for saponin concentrations of 50 mg/L, 100 mg/L, 200 mg/L). Treatment with Asparagus saponins for 24 hours increased the intracellular level of ros and Ca(2+), lowered the pH, activated intracellular mptp, and decreased mmp in a dose-dependent manner. Treatment also increased the activity of caspase-9 and caspase-3, downregulated the expression of Bcl2, upregulated the expression of Bax, and induced release of CytC and activation of caspase-3.

CONCLUSIONS

Asparagus saponins induce apoptosis in HepG2 cells through a mitochondrial-mediated and caspase-dependent pathway, suggesting that they may be a potent agent for the treatment of hepatocellular carcinoma.

Evaluation of the compositional and nutritional values of phytase transgenic corn to conventional corn in roosters

Three experiments were conducted to evaluate the compositional and nutritional values of corn grains [phytase transgenic corn (PTC) and isogenic conventional corn (CC)] and compare the efficacy of corn-based phytase and extraneous microbial phytase for enhancing the utilization of phytate phosphorus (P) in single corn or corn-soybean mixed meals (corn:soybean = 2.5:1, wt:wt) fed to roosters. Following a 48-h fasting period, 16 roosters were given 50 g of each sample via crop intubation and excreta were collected for 48 h. Nitrogen-free and phosphorus-free diets were used to evaluate endogenous amino acid and endogenous P losses, respectively. Chemical composition was not different between PTC and CC, whereas the phytase content for PTC was greater than CC (8,047 vs. 37 FTU/kg of corn, DM basis; P < 0.001). No difference was observed in the TME and true amino acid availability values between the PTC and CC in roosters. The true P utilization for PTC was greater than CC (37.92 vs. 55.85%; P < 0.001), and CC and PTC contained 0.13 and 0.19% available P (AP, DM basis; P < 0.001), respectively. There was no difference in P utilization (72.76 vs. 70.23%; P > 0.05) between roosters fed PTC and extraneous microbial phytase in equivalent FTU/kg of diets. The results of this study indicated that the chemical composition, TME, and true amino acid availability in PTC are essentially equivalent to that in CC, and the true P utilization for roosters is higher in PTC than in CC. Corn expressing phytase is as efficacious as equivalent microbial phytase when supplemented in corn-soybean diets for chickens.

First Report of Peanut Cylindrocladium Black Rot Caused by Cylindrocladium parasiticum in Fujian Province, Eastern China

During late July and early August of 2010, a serious disease of peanut (Arachis hypogaea L.) resembling Cylindrocladium black rot (CBR) was found in Longyan City, Fujian Province of Eastern China. Aboveground symptoms were chlorosis and yellowing of leaves, a black rot of the basal stem and pegs, and wilting of the vines. Underground plant parts (including pods, pegs, taproots, and hypocotyls) were blackened and rotted. Orange-to-reddish spherical fruiting bodies appeared on the lesions of the basal stems and pegs of peanut. Disease incidence was approximately 20%. A fungus was consistently isolated from the edge of lesions on potato dextrose agar (PDA) amended with streptomycin and incubated at 25°C. The fungus produced white-to-pale buff mycelia with a yellowish brown pigment. Optimum growth of the fungus on PDA was at 25 to 30°C. Conidiophores were borne laterally on a stipe that terminated in a hyaline, globose vesicle measuring 5.5 × 10.9 μm in diameter. Conidia were hyaline, cylindrical, rounded at both ends, slightly wider at the base than at the apex, with one to three septa (mostly one septa), and measured 27.3 to 70.9 × 4.1 to 8.2 μm. Orange-to-reddish perithecia were readily formed in old cultures. The perithecia were subglobose to oval or obovate and measured 215.6 to 609.4 × 309.4 to 496.9 μm. The asci were hyaline, clavate, thin walled, long stalked, with each containing eight ascospores. Ascospores were hyaline, falcate, had one septum, and measured 27.3 to 54.5 × 4.1 to 6.8 μm. The fungus was identified as Cylindrocladium parasiticum Crous, M.J. Wingfield, & Alfenas (teleomorph Calonectria ilicicola) (1,2). The beta-tubulin gene fragment was amplified using the T1/Bt2b primers (3) and sequenced. The sequences of three isolates (GenBank Accession Nos. JF343965, JF429656, and JF429657), when compared with existing sequences in GenBank, had 95 to 99% sequence identity with Calonectria ilicicola (GenBank Accession Nos. AY725643 and AY725639). Pathogenicity tests were conducted by first culturing the fungus on wheat kernels for 2 weeks. Inoculated kernels were then used as inoculum and mixed with sterilized soil in a proportion of 1:20 by weight in plastic pots (10 × 9 cm). Noninoculated wheat kernels were mixed with sterilized soil in the same proportion and served as the control. Two-week-old peanut seedlings (cv. Yueyou No. 7) were transplanted into inoculated or noninoculated pots. There were five plants per pot and each treatment was replicated four times. The plants were incubated in a greenhouse at 25 ± 2°C. All of the treated plants exhibited typical basal stem and root rot symptoms of CBR 2 weeks after inoculation, while all of the control plants remained healthy. C. parasiticum was reisolated from the diseased plants. To our knowledge, this is the first report of CBR on peanut in Fujian Province in Eastern China. The disease has been previously reported in Guangdong Province in Southern China but is not known elsewhere (4). This pathogen may pose a serious threat to peanut production in China, where peanut is an important crop. References: (1) D. K. Bell and E. K. Sobers. Phytopathology 56:1361, 1966. (2) P. W. Crous et al. Mycol. Res. 97:889, 1993. (3) P. W. Crous et al. Can. J. Bot. 77:1813, 1999. (4) R. Pan et al. Plant Pathol. 58:1176, 2009.

The mechanism of memory impairment induced by Aβ chronic administration involves imbalance between cytokines and neurotrophins in the rat hippocampus

It has been demonstrated that the onset and progression of Alzheimer's disease (AD) are associated with inflammatory disorders in the brain. Although the interactions of inflammatory cytokines with neurotrophins have been reported in vitro, the balance change between inflammatory cytokines and neurotrophic factors (NTFs), such as nerve growth factor (NGF), brain derived neurotrophic factor (BDNF), and glial cell line-derived neurotrophic factor (GDNF), due to amyloid β (Aβ) chronic administration in vivo is still unclear. The hypothesis of the present study was that the accumulation of Aβ activated glial cells to produce inflammatory mediators and NTFs to maintain the neurons survival, however the failure of crosstalk between NTFs and inflammatory cytokines might occur in the brain and the NTFs expressions would decrease after Aβ chronic treatment, which, therefore, would contribute to the neuronal death and memory impairments. Thus, the present study measured the learning and memory behavior, glial cells activities, cytokines (IL-1α, IL-1β and TNF-α) concentrations and NTFs (NGF, BDNF and GDNF) gene and protein levels in rats after i.c.v injection of Aβ(25-35) for 14 days. The results showed that Aβ (25-35)-treated animals exhibited failure of balance between inflammatory cytokines and NTFs system (increased cytokines levels, decreased NGF protein expression and reduced NTFs gene transcriptions), which might contribute to the cognitive impairments. The findings from this study provide valuable evidence that correct regulation of the crosstalk between inflammatory cytokines and NTFs could be a direction for AD therapy in the future.

Bactericidal activity of grass carp Ctenopharyngodon idella C9-deficient serum against Aeromonas hydrophila

Neutralizing complement C9 in grass carp Ctenopharyngodon idella sera with rabbit anti-C9 sera against fish complement C9, demonstrated that bactericidal activity against Aeromonas hydrophila of the C9-deficient fish sera was greatly impaired. These results indicated that the fish complement C9 plays a key role in pathogen killing through the lytic pathway.

First Report of Peanut Foot Rot Caused by Neocosmospora vasinfecta var. africana in Jiangxi Province, China

From June 2009 to November 2010, a disease was observed on peanut (Arachis hypogaea L.) in Ganzhou City, Jiangxi Province, China. Infected plants initially exhibited yellow leaves, then defoliated, and finally wilted and died. Basal stems, pegs, pods, and roots became black and rotted, with many orange-brown spherical fruiting bodies emerging on the lesions. Disease incidence reached as high as 30% in some plots, especially in those covered with plastic sheets after planting to control weeds. Isolations from 68 diseased plants were conducted on potato dextrose agar (PDA) amended with streptomycin sulfate and incubated at 25°C. A fungus was consistently isolated from the edge of the lesions. Mycelia grew at a linear rate of 3.9 mm per day on PDA at 25°C forming a pale buff, floccose colony with abundant orange-red perithecia. Perithecia were globose to pyriform, ostiolate and with a short neck, and measured 151 to 353 × 141 to 313 μm. Asci were narrowly cylindrical to clavate, thin walled with a short stalk, measured 100 to 160 μm high and 9 to 15 μm in diameter, and were eight spored. Ascospores were uniseriately arranged, globose to ellipsoid, nonseptate, thick walled, hyaline to pale yellow, and measured 7 to 16 × 7 to 12 μm. Scanning electron microscopy revealed that the wall of the ascospores had cerebriform ornamentation. Conidia were cylindrical to oblong-ellipsoidal, hyaline, most one celled, and measured 3 to 15 × 1 to 5 μm, aggregating in a gelatinous mass on the tip of the conidiogenous cell, which usually arose directly from the vegetative mycelium. The fungus was identified as Neocosmospora vasinfecta var. africana (anamorph Acremonium sp.) (1). The rDNA internal transcribed spacer (ITS) region of the fungus was amplified with universal primers ITS1/ITS4 and sequenced. The sequences of a representative isolate (No. N-JXLN02) were submitted to GenBank (Accession No. JF708085) and BLAST searches showed 99 to 100% similarity with sequences of N. vasinfecta deposited in GenBank (Accession Nos. HM461900, HM461901, and AY381142 ). Pathogenicity tests were conducted on 36 2-week-old peanut seedlings, cv. Yueyou No. 13, in plastic pots. Plants were inoculated by drenching the soil near the shoot with a mixed suspension of conidia and ascospores (10⁵ spores per ml). Control plants were treated with sterile water. All plants were then incubated in a moist chamber at 25 ± 2°C. Fifteen days after inoculation, all inoculated plants showed lesions on basal stems and black root rot similar to that observed on naturally infected plants. No disease was observed on control plants. The pathogen was reisolated from infected tissues. To our knowledge, this is the first finding of Neocosmospora foot rot of peanut in Jiangxi Province, where outbreaks of this disease have been observed in several counties. The pathogen will pose a threat to peanut, which is a major oil crop in China. It has been previously reported in Taiwan (2) and recently in Guangdong Province, though the subspecies of the pathogen was not identified in the latter case (3). References: (1) P. F. Cannon and D. L. Hawksworth. Trans. Br. Mycol. Soc. 82:673, 1984. (2) J. W. Huang et al. Plant Pathol. Bull. 1:203, 1992. (3) R. Pan et al. Plant Pathol. 59:1172, 2010.

Effects of alpha-lipoic acid supplementation on antioxidative ability and performance of sows and nursing piglets

The current study was carried out to determine the effects of alpha-lipoic acid (LA) supplementation during late-gestation and lactation on antioxidative ability and performance of sows and their nursing piglets. A total of 160 multiparous sows were randomly allocated to four treatments with 40 replicates per treatment according to parity number and backfat (BF) thickness. Sows were fed 1 of 4 diets from day 85 of gestation to day 21 of lactation. Diets were control without LA; 400 ppm LA supplementation; 600 ppm LA supplementation; and 800 ppm LA supplementation. BF thickness of sows was determined on day 85 and 110 of gestation and days 1 and 21 of lactation. Piglet bodyweight was measured at birth, days 7, 14 and 21. Blood samples were obtained from the sows, and average daily feed intake (ADFI) of the sows during lactation was recorded. There were no differences in BF thickness or ADFI among treatment groups. Dietary LA supplementation resulted in a decrease in blood urea nitrogen (p < 0.01) concentration at days 110 of gestation. Dietary 800 ppm LA increased serum glutathione peroxidase (GSH-Px) activity (p < 0.05) and reduced maleic dialdehyde levels (p < 0.01) of sows compared with the control diet at days 21 of lactation. Alpha-lipoic acid supplementation increased the birthweight and weaning weight of piglets (p < 0.01) compared with the control group. Weight gains of piglets from sows fed the 800 ppm LA diets were greater (p < 0.01) between days 7 and 14 compared with piglets from control sows. Weight gains of piglets from sows fed the LA-supplemented diets were greater between days 14 and 21 (p < 0.05) and between days 1 and 21 (p < 0.01) compared with piglets from control-fed sows. In conclusion, the results indicate that antioxidant LA was effective in enhancing antioxidant enzymes activity and improving the performance of sows and their nursing piglets.

First Report of Soybean Neocosmospora Stem Rot Caused by Neocosmospora vasinfecta var. vasinfecta in China

During October 2009, the occurrence of a disease on soybean (Glycine max) was observed in several fields in Boluo County and Zengcheng City, Guangdong Province. Top leaves of infected plants initially turned yellow and plants eventually were defoliated, while stems and roots became black and rotted. The stem lesions sometimes extended 10 to 15 cm upward from the soil surface. Orange-to-brown spherical fruiting bodies, which were very similar with those of the soybean red crown rot pathogen, scattered or congregated on the stem lesions. Plants with symptoms were sampled from fields. Fruiting bodies were excised from diseased tissues. Microscopic examination revealed that they were perithecia, globose to pyriform, ostiolate with a short neck, and measured 160 to 298 × 151 to 235 μm. Under gentle pressure, asci and ascospores were exuded from these perithecia. Asci were eight spored, narrowly cylindrical to clavate, thin walled, with a short stalk, and measured 58 to 124 μm long and 8 to 15 μm in diameter. Ascospores were uniseriately arranged, globose to ellipsoid, thick walled, one celled, hyaline to pale, and measured 14 to 17 × 8 to 12 μm. Isolation was made from stem tissues at the edge of disease lesions on potato dextrose agar (PDA) amended with streptomycin sulfate and incubated at 25°C. Mycelia were white and floccose. Conidia were cylindrical to oblong-ellipsoidal, hyaline, one celled, and measured 6 to 22 × 2 to 5 μm, aggregating in a slimy mass on the apex of the conidiogenous cell. Abundant orange-to-brown spherical perithecia were produced on the colony. Ascospores had walls with a rugose ornamentation that could be clearly seen under a scanning electron microscope. The fungus was identified as Neocosmospora vasinfecta var. vasinfecta (anamorph Acremonium sp.) (1). The internal transcribed spacer (ITS) region of rDNA of two isolates were amplified with universal primers ITS1/ITS4 and sequenced (GenBank Accession No. JF705861 and JF705862), and comparisons with GenBank accessions showed 99% similarity with N. vasinfecta strain Pec070 (Accession No. FJ940902) and strain NRRL22497 (Accession No. AY381142). Pathogenicity tests were conducted. Five, 3-week-old seedlings of soybean cv. Huaxia No. 3 planted in plastic pots (20 cm in diameter) were wounded with a needle at the base of the stem below the soil line and near the root system, and then inoculated by drenching the soil with a conidial suspension (10⁵ per ml). Control plants were inoculated with sterile water. There were six replicates for each treatment. The treated plants were incubated at 25 ± 2°C in a greenhouse. All inoculated plants exhibited symptoms of leaf yellowing and black rot of stems and roots 3 weeks after inoculation. N. vasinfecta var. vasinfecta was reisolated from the diseased plants. All control plants remained healthy. To our knowledge, this is the first observation of Neocosmospora stem rot of soybean in China. The pathogen could pose a threat to soybean, which is a major crop in China. This disease has been previously reported in the United States though the anamorph of the pathogen has either not been identified or has been identified as a Cylindrocarpon sp. (2,4). This fungus is also associated with human infections (3). References: (1) P. F. Cannon and D. L. Hawksworth. Trans. Br. Mycol. Soc. 82:673, 1984. (2) F. A. Gray et al. Plant Dis. 64:321, 1980. (3) P. Manikandan et al. Med. Mycol. 46:279, 2008. (4) D. V. Phillips. Phytopathology 62:612, 1972.

C6-ceramide synergistically potentiates the anti-tumor effects of histone deacetylase inhibitors via AKT dephosphorylation and α-tubulin hyperacetylation both in vitro and in vivo

Histone deacetylase inhibitors (HDACIs) have shown promising anti-tumor effects for a variety of malignancies, however, many tumors are reportedly resistant to them. In this study, we made a novel discovery that co-administration of HDACIs (Trichostatin A (TSA) and others) and exogenous cell-permeable short-chain ceramide (C6) results in striking increase in cancer cell death and apoptosis in multiple cancer cells. These events are associated with perturbations in diverse cell signaling pathways, including inactivation of Akt/mTOR and increase in α-tubulin acetylation (both in vivo and in vitro). TSA interacts in a highly synergistic manner with C6-ceramide to disrupt HDAC6/protein phosphatase 1 (PP1)/tubulin complex, to induce α-tubulin hyperacetylation, and to release and activate PP1, which then leads to AKT dephosphorylation and eventually causes cancer cell death. Interestingly, TSA itself results in short-term ceramide accumulation, which as a result of metabolic (glycosylation) removal, does not result in evident increase of cancer cell death. However, adding C6-ceramide led to a very pronounced increase in ceramide level and marked increase in cell death. Importantly, the effective synergistic anti-tumor activity of TSA plus C6-ceramide is also seen in in vivo mice xenograft pancreatic and ovarian cancer models, indicating that this regimen (HDACI plus C6-ceramide) may represent a more effective form of therapy against pancreatic and ovarian carcinoma.

Preparation, purification and characteristics of an aflatoxin degradation enzyme from Myxococcus fulvus ANSM068

AIMS

To prepare, purify and characterize an extracellular enzyme from Myxococcus fulvus ANSM068, designated as myxobacteria aflatoxin degradation enzyme (MADE), which possesses degradation activity against aflatoxin B(1) (AFB(1) ), G(1) (AFG(1) ) and M(1) (AFM(1) ) in solution.

METHODS AND RESULTS

The culture supernatant of strain M. fulvus demonstrated high degradation ability against AFB(1) (71·89%), AFG(1) (68·13%) and AFM(1) (63·82%) after 48 h of incubation. An enzyme was purified from the supernatant of M. fulvus using ethanol precipitation and chromatography on DEAE-Sepharose and Superdex 75. An overall 166-fold purification of the enzyme with a recovery of 57% and a final specific activity of 569·44 × 10(3) U mg(-1) was obtained using the present purification protocol. The apparent molecular mass of MADE was estimated to be 32 kDa by SDS-PAGE. AFG(1) and AFM(1) were significantly degraded, by 96·96 and 95·80%, respectively, when treated with pure MADE (100 U ml(-1) ) produced by strain ANSM068. MADE exhibited the largest amount of activity at 35°C and pH 6·0, with Mg(2+) ions greatly promoting and Zn(2+) strongly inhibiting MADE activity.

CONCLUSIONS

An aflatoxin DEGRADATION ENZYME FROM BACTERIAL ISOLATES CAN EFFECTIVELY REMOVE AFLATOXIN B(1) , G(1) AND M(1) IN SOLUTION.

SIGNIFICANCE AND IMPACT OF THE STUDY

The high activity and wide temperature and pH range of MADE for the degradation of aflatoxin have promising applications in control of mycotoxins during food and feed processing.

Caspase-8 and p38MAPK in DATS-induced apoptosis of human CNE2 cells

Nasopharyngeal carcinoma is a common malignancy in Southern China of uncertain etiologic origin. Diallyl trisulfide (DATS), one of the major components of garlic (Allium sativum), is highly bactericidal and fungicidal. In this study, we investigated the function of p38 mitogen-activated protein kinase (MAPK) and caspase-8 in DATS-induced apoptosis of human CNE2 cells using MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide], flow cytometry assay, and Western blotting. After CNE2 cells were treated with DATS (50, 100, or 150 μM) for 24 h, cell viability rates were 75.9, 63.4 and 39.6%, and apoptosis rates were 24.5, 36.9, and 62.4%, respectively. The data showed that DATS induced CNE2 cell death in a dose-dependent manner. After human CNE2 cells were treated with 100 μM DATS and inhibitors (10 μM SB203580 and Z-LETD-FMK for p38MAPK and caspase-8, respectively), changes in cell viability and apoptosis and in p38MAPK and caspase-8 activity were detected. Cell viability rates were 66.5 and 68.1% and decreased 9.9 and 11.5% compared with inhibitor treatment alone. Apoptosis rates were 31.53 and 29.98% and increased 9.1 and 10% compared with inhibitor treatment alone. The results indicated that DATS activates p38MAPK and caspase-8, but both inhibitors have an effect on P38MAPK and caspase-8 activity. In conclusion, our data indicate that p38MAPK and caspase-8 are involved in the process of DATS-induced apoptosis in human CNE2 cells and interact with each other.

Implementing a 48 h EWTD-compliant rota for junior doctors in the UK does not compromise patients' safety: assessor-blind pilot comparison

BACKGROUND

There are currently no field data about the effect of implementing European Working Time Directive (EWTD)-compliant rotas in a medical setting. Surveys of doctors' subjective opinions on shift work have not provided reliable objective data with which to evaluate its efficacy.

AIM

We therefore studied the effects on patient's safety and doctors' work-sleep patterns of implementing an EWTD-compliant 48 h work week in a single-blind intervention study carried out over a 12-week period at the University Hospitals Coventry & Warwickshire NHS Trust. We hypothesized that medical error rates would be reduced following the new rota.

METHODS

Nineteen junior doctors, nine studied while working an intervention schedule of <48 h per week and 10 studied while working traditional weeks of <56 h scheduled hours in medical wards. Work hours and sleep duration were recorded daily. Rate of medical errors (per 1000 patient-days), identified using an established active surveillance methodology, were compared for the Intervention and Traditional wards. Two senior physicians blinded to rota independently rated all suspected errors.

RESULTS

Average scheduled work hours were significantly lower on the intervention schedule [43.2 (SD 7.7) (range 26.0-60.0) vs. 52.4 (11.2) (30.0-77.0) h/week; P < 0.001], and there was a non-significant trend for increased total sleep time per day [7.26 (0.36) vs. 6.75 (0.40) h; P = 0.095]. During a total of 4782 patient-days involving 481 admissions, 32.7% fewer total medical errors occurred during the intervention than during the traditional rota (27.6 vs. 41.0 per 1000 patient-days, P = 0.006), including 82.6% fewer intercepted potential adverse events (1.2 vs. 6.9 per 1000 patient-days, P = 0.002) and 31.4% fewer non-intercepted potential adverse events (16.6 vs. 24.2 per 1000 patient-days, P = 0.067). Doctors reported worse educational opportunities on the intervention rota.

CONCLUSIONS

Whilst concerns remain regarding reduced educational opportunities, our study supports the hypothesis that a 48 h work week coupled with targeted efforts to improve sleep hygiene improves patient safety.

Broadband ground-plane cloak

The possibility of cloaking an object from detection by electromagnetic waves has recently become a topic of considerable interest. The design of a cloak uses transformation optics, in which a conformal coordinate transformation is applied to Maxwell's equations to obtain a spatially distributed set of constitutive parameters that define the cloak. Here, we present an experimental realization of a cloak design that conceals a perturbation on a flat conducting plane, under which an object can be hidden. To match the complex spatial distribution of the required constitutive parameters, we constructed a metamaterial consisting of thousands of elements, the geometry of each element determined by an automated design process. The ground-plane cloak can be realized with the use of nonresonant metamaterial elements, resulting in a structure having a broad operational bandwidth (covering the range of 13 to 16 gigahertz in our experiment) and exhibiting extremely low loss. Our experimental results indicate that this type of cloak should scale well toward optical wavelengths.

The epidemiology of HIV infection in Zambia

Population surveys of health and fertility are an important source of information about demographic trends and their likely impact on the HIV/AIDS epidemic. In contrast to groups sampled at health facilities they can provide nationally and regionally representative estimates of a range of variables. Data on HIV-sero-status were collected in the 2001 Zambia Demographic and Health Survey (ZDHS) and made available in a separate data file in which HIV status was linked to a very limited set of demographic variables. We utilized this data set to examine associations between HIV prevalence, gender, age and geographical location. We applied the generalized geo-additive semi-parametric model as an alternative to the common linear model, in the context of analyzing the prevalence of HIV infection. This model enabled us to account for spatial auto-correlation, non-linear, location effects on the prevalence of HIV infection at the disaggregated provincial level (nine provinces) and assess temporal and geographical variation in the prevalence of HIV infection, while simultaneously controlling for important risk factors. Of the overall sample of 3950, 54% was female. The overall HIV-positivity rate was 565 (14.3%). The mean age at HIV diagnosis for male was 30.3 (SD=11.2) and 27.7 (SD=9.3) for female respectively. Lusaka and Copperbelt have the first and second highest prevalence of AIDS/HIV (marginal odds ratios of 3.24 and 2.88, respectively) but when the younger age of the urban population and the spatial auto-correlation was taken into account, Lusaka and Copperbelt were no longer among the areas with the highest prevalence. Non-linear effects of age at HIV diagnosis are also discussed and the importance of spatial residual effects and control of confounders on the prevalence of HIV infection. The study was conducted to assess the spatial pattern and the effect of confounding risk factors on AIDS/HIV prevalence and to develop a means of adjusting estimates of AIDS/HIV prevalence on the important risk factors. Controlling for important risk factors, such as geographical location (spatial auto-correlation), age structure of the population and gender, gave estimates of prevalence that are statistically robust. Researchers should be encouraged to use all available information in the data to account for important risk factors when reporting AIDS/HIV prevalence. Where this is not possible, correction factors should be applied, particularly where estimates of AIDS/HIV prevalence are pooled in systematic reviews. Our maps can be used for policy planning and management of AIDS/HIV in Zambia.

Effects of dietary inosinic acid on carcass characteristics, meat quality, and deposition of inosinic acid in broilers

An experiment was conducted to evaluate the effects of dietary inosinic acid (inosine 5'-monophosphate, IMP) on carcass characteristics, meat quality, and deposition of IMP in Arbor Acres broilers. A total of two hundred forty 1-d-old male Arbor Acres broilers were allocated to 4 inosinic acid treatments (0, 0.25, 0.50, and 0.75% dietary IMP supplementation). Birds were slaughtered at 42 d old. Dietary IMP did not significantly affect the carcass characteristics of broilers. No significant difference among treatments was observed in muscle pH within 1 h or at 24 h postmortem (PM), or in the decrease of muscle pH within 24 h PM. Inosinic acid had no marked effect on the color of breast muscle or Hunter L* and a* values of thigh muscle. Hunter b* values in thigh muscle were lower (P < 0.05) in the 0.75% IMP supplementation group than in the control group. Both breast and thigh muscle of birds fed with 0.25% IMP diet resulted in a lower (P < 0.05) shear force value compared with those fed with the other diets. All of the test groups had greater (P < 0.05) deposition of IMP in breast and thigh muscle than that of the control group with the exception of the 0.75% IMP supplementation group for thigh muscle. Greater (P < 0.05) corrected IMP value in breast muscle was detected for the test groups compared with the control group. These results suggest that extraneous IMP addition may contribute to the improvement of growth, meat quality, and deposition of IMP in broilers.