The predictive model for strength of inclined screws as shear connection in timber-concrete composite floor

Interest in timber-concrete composite (TCC) floors has increased over the last 30 years. TCC technology relies on timber and concrete members acting compositely together. Both timber and concrete exhibit a quite brittle behaviour in bending/tension and compression respectively whilst the shear connection is identified as the only contributor of ductile behaviour. Therefore, the strength, stiffness and arrangement of the shear connection play a crucial role in the structural design of TCC. There are only few investigations on analytical closed-form equation to predict the stiffness and strength of TCC joints as input values to design a partially composite floor. For example, Johansen's yield theory was adopted as European yield model in Eurocode 5. However, the equations are limited to vertically inserted dowels or screws and Eurocode 5 recommends that the strength and stiffness of unconventional joints should be determined by push-out tests. Previous investigations reported that the inclined shear connector significantly increase the initial stiffness and ultimate strength of the TCC joints and consequently composite floor. This paper presents a model for the strength ofTCC joint using crossed (±45°) proprietary screws (SFS Intec). The Johansen yield theory is extended to derive the strenght model of TCC joint with crossed (±45°) screws which are loaded in tension and compression. The model is an upper bound plastic collapse model that assumes the behaviour of timber and screw perfectly plastic with undamaged concrete. The failure modes considers of yield of screw, in tension or shear, and some combined modes assuming screw withdrawal, lateral crushing of the timber and the development of plastic hinges in the screw. The experimental aspect of the research consists of push-out tests and aims to verify the strength model of TCC joints with inclined screws. The failure modes are also investigated. The model seems to be reasonably accurate in predicting both the characteristic strength and failure mode. This research suggests the model to facilitate the design of inclined screw shear connections for TCC construction. © 2013 Taylor & Francis Group

Production and evaluation of doubled haploid lines of barley via detached-tiller culture method

This research was conducted to compare the classic (C) and detached-tiller methods (a: sterile by clip and scissors D1; b: sterile by hot water D2) for producing haploids in barley. The parental materials used in this research were F1 four genotypes of Hordeum vulgare: B1: Reihane × Legia; B2: Reihan × Igri; B3: Kavir × Igri; B4: Kavir × Legia, and the Hordeum bulbosum was PB1 genotype (Plant Breeding Institute). The traits such as seed set percentage, embryo development, haploid seedling development and produced doubled haploid lines were analyzed statically using χ2 test. The comparison was made among arable barley B1, B2, B3, B4 crossing wild barley of H. bulbosum. In C approach, there was no significant difference concerning the percent of forming seed, embryo and haploid production. While in D1 approach, there was a significant difference in embryo forming percent but no significant difference was observed for haploid plant and seed set percent. Moreover, in D2 approach, there was a significant difference for seed set percent. However, for haploid production and embryo development percent, the approach D1 in regards with the percent of forming embryo and production of haploids was superior to the other two approaches, C and D2.Key words: Detached-tiller culture, haploid, doubled haploid, Hordeum bulbosum, Hordeum vulgare

Helicobacter pylori and cancer among adults in Uganda

Data from Africa on infection with Helicobacter pylori (H. pylori) are sparse. Therefore, as part of an epidemiological study of cancer in Uganda, we investigated the prevalence and determinants of antibodies against H. pylori among 854 people with different cancer types and benign tumours. Patients were recruited from hospitals in Kampala, Uganda, interviewed about various demographic and lifestyle factors and tested for antibodies against H. pylori. In all patients combined, excluding those with stomach cancer (which has been associated with H. pylori infection), the prevalence of antibodies was 87% (723/833) overall, but declined with increasing age (p = 0.02) and was lower among people who were HIV seropositive compared to seronegative (p <0.001). Otherwise, there were few consistent epidemiological associations. Among those with stomach cancer, 18/21 (86%) had anti-H. pylori antibodies (odds ratio 0.8, 95% confidence intervals 0.2–2.9, p = 0.7; estimated using all other patients as controls, with adjustment for age, sex and HIV serostatus). No other cancer site or type was significantly associated with anti-H. pylori antibodies. The prevalence of H. pylori reported here is broadly in accord with results from other developing countries, although the determinants of infection and its' role in the aetiology of gastric cancer in Uganda remain unclear

Clinical improvement and radiological progression in a girl with early onset scoliosis (EOS) treated conservatively – a case report

BACKGROUND: Chêneau-Brace treatment of a certain standard reduces the rate of surgery, prevents progression and in a certain patient population leads to marked improvement of Cobb angle and cosmetic appearance. During the last two years a patient refusing surgery with a double major curvature of initially 60° showed a clear cosmetic improvement and a clear radiological progression at the same time. The findings of this patient have been reviewed in order to find out how cosmetic appearance and Cobb angle can develop differently. METHODS: The patient entered conservative treatment at the age of 13 years, premenarchial with Tanner II and a Cobb angle of 60° thoracic and 59° lumbar. The angle of trunk rotation (ATR; Scoliometer) was 13° thoracic and 13° lumbar. We have documented the findings of this patient (Surface topography, ATR, Cobb angles and angles of vertebral rotation (according to Raimondi) during the treatment period (27 Month) until 2 years after the onset of menarche. RESULTS: After a treatment time of 27 Month the Cobb angle increased to 74° thoracic and 65° lumbar. The angles of vertebral rotation according to Raimondi increased slightly from 26° thoracic and 28° lumbar to 30° thoracic and 28° lumbar. The ATR improved to 12° thoracic and 5° lumbar while Lateral deviation improved from 22,4 mm to 4,6 mm and average surface rotation improved from 10,6° to 6°. In the X-rays a reduction of decompensation was visible. The patient felt comfortable with the cosmetic result. CONCLUSION: Conservative treatment may improve cosmetic appearance while the curve progresses radiologically. This could be explained by assuming that (1) the Rigo Chêneau brace is able to improve cosmetic appearance by changing the shape of the thorax when the curve itself is too stiff to be corrected by a brace, that (2) reduction of decompensation leads to significant cosmetical improvements or (3) that the patient gained weight and therefore the deformation is masked. However, the weight the patient gained cannot explain the cosmetical improvement in this case. Conservative treatment with a certain standard of quality seems a viable alternative for patients with Cobb angles of > 60° when surgical treatment is refused. Specialists in scoliosis management should be aware of the fact that curve progression can occur even if the clinical measurements show an improvement

Distribution of mtDNA haplotypes in North-Atlantic humpback whales:The influence of behavior on population structure

Samples from 136 humpback whales Megaptera novaeangliae, representing 5 feeding aggregations in the North Atlantic and 1 in the Antarctic, were analyzed with respect to the sequence variation in the mitochondrial (mt) control region. A total of 288 base pairs was sequenced by direct sequencing of asymmetrically amplified DNA. Thirty-one different haplotypes were identified. The nucleotide diversity for the total sample was estimated to be 2.6 %, which is high relative to other North Atlantic cetaceans. The degree of genetic differentiation in various subsets of the samples was estimated and tested for statistical significance by Monte Carlo simulations. Significant degrees of heterogeneity were found between the Antarctic and all North Atlantic areas, as well as between Iceland and the western North Atlantic samples. A genealogical tree was estimated for the 31 haplotypes and rooted with the homologous sequence from a fin whale Balaenoptera physalus. The branching pattern in the genealogical tree suggests that the North Atlantic Ocean has been populated by 2 independent influxes of humpback whales. The combined results from the homogeneity tests and the genealogical tree indicate that behaviour (in this case maternally directed site fidelity to a foraging area) can influence the population structure of marine cetaceans on an evolutionary time scale

Analyticity, Unitarity and One-loop Graviton Corrections to Compton Scattering

We compute spin-flip cross section for graviton photoproduction on a spin-1/2 target of finite mass. Using this tree-level result, we find one-loop graviton correction to the spin-flip low-energy forward Compton scattering amplitude by using Gerasimov-Drell-Hearn sum rule. We show that this result agrees with the corresponding perturbative computations, implying the validity of the sum rule at one-loop level, contrary to the previous claims. We discuss possible effects from the black hole production and string Regge trajectory exchange at very high energies. These effects seem to soften the UV divergence present at one-loop graviton level. Finally, we discuss the relation of these observations with the models that involve extra dimensions.Comment: 15 pages, 3 figure

A two-year participatory intervention project with owners to reduce lameness and limb abnormalities in working horses in Jaipur, India

Participatory methods are increasingly used in international human development, but scientific evaluation of their efficacy versus a control group is rare. Working horses support families in impoverished communities. Lameness and limb abnormalities are highly prevalent in these animals and a cause for welfare concern. We aimed to stimulate and evaluate improvements in lameness and limb abnormalities in horses whose owners took part in a 2-year participatory intervention project to reduce lameness (PI) versus a control group (C) in Jaipur, India.In total, 439 owners of 862 horses participated in the study. PI group owners from 21 communities were encouraged to meet regularly to discuss management and work practices influencing lameness and poor welfare and to track their own progress in improving these. Lameness examinations (41 parameters) were conducted at the start of the study (Baseline), and after 1 year and 2 years. Results were compared with control horses from a further 21 communities outside the intervention. Of the 149 horses assessed on all three occasions, PI horses showed significantly (P<0.05) greater improvement than C horses in 20 parameters, most notably overall lameness score, measures of sole pain and range of movement on limb flexion. Control horses showed slight but significantly greater improvements in four parameters, including frog quality in fore and hindlimbs.This participatory intervention succeeded in improving lameness and some limb abnormalities in working horses, by encouraging changes in management and work practices which were feasible within owners’ socioeconomic and environmental constraints. Demonstration of the potentially sustainable improvements achieved here should encourage further development of participatory intervention approaches to benefit humans and animals in other contexts