6,802 research outputs found

    Priorities for use of passive and active solar systems in cold climate buildings.

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    Increasing consumption of energy derived from fossil fuels while has caused rapid economic growth in different communities, due to pollutant emission and its consequences, has faced the world with risky changes as well. Limitation of this non-renewable sources cased that energy consumption optimization policy become the governments work programs outline. On the other hand, growth of science and technology in the world has led to transformation of the commonly used methods of energy consumption, and discovering new energy sources has caused a major evolution in development of human societies. In this regard, the relatively simple technology, not  polluting the environment etc. are the reasons that make the necessity of using solar energy more and more evident. Since most of the energy is consumed in buildings, functional identification of optimization systems in buildings is essential. The present study aimed to introduce, evaluate, and set priorities for use of energy systems in buildings. To this aim, first, all systems were identified and their fields of application were specified. Then, in a comparative study, the priorities for use of the systems and their application were examined in building sector.Key words: energy, solar system, active systems, passive systems

    Intrinsic function of the peptidylarginine deiminase PADI4 is dispensable for normal haematopoiesis.

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    Peptidylarginine deiminases (PADIs) are strongly associated with the development of autoimmunity, neurodegeneration and cancer but their physiological roles are ill-defined. The nuclear deiminase PADI4 regulates pluripotency in the mammalian pre-implantation embryo but its function in tissue development is unknown. PADI4 is primarily expressed in the bone marrow, as part of a self-renewal-associated gene signature. It has been shown to regulate the proliferation of multipotent haematopoietic progenitors and proposed to impact on the differentiation of haematopoietic stem cells (HSCs), suggesting that it controls haematopoietic development or regeneration. Using conditional in vivo models of steady state and acute Padi4 ablation, we examined the role of PADI4 in the development and function of the haematopoietic system. We found that PADI4 loss does not significantly affect HSC self-renewal or differentiation potential upon injury or serial transplantation, nor does it lead to HSC exhaustion or premature ageing. Thus PADI4 is dispensable for cell-autonomous HSC maintenance, differentiation and haematopoietic regeneration. This work represents the first study of PADI4 in tissue development and indicates that pharmacological PADI4 inhibition may be tolerated without adverse effects

    Microbial status of smoked fish, scombia scombia sold in Owerri, Imo state, Nigeria

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    As one of the common sources of protein available to man, fish is highly consumed due to its lower cholesterol content and price. So it forms a rich protein source for both poor and rich. As a part of checkmating the public health risks associated with this general dependence of the population on fish, the microbiological assessment of smoked fish, Scombia, scombia sold in Owerri was embarked on with the aim of ascertaining the microbial quality, the presence and prevalence of microorganisms of public health importance. A total of one hundred and eight (108) samples were collected from the smoking Factory, Open Market and Hawkers. These were analyzed microbiologically for viable heterotrophic bacteria and fungi count on Nutrient and Potato dextrose agar respectively, using pour plate method and coliform count in MacConkey broth by multiple tube method (MPN). The mean value results from the analysis revealed high microbial contamination in all the samples. The resultant data were analyzed statistically using randomized block design of Analysis of Variance (ANOVA) at 95% level of confidence and the difference were separated using the least significance difference (LSD). The mean results of viable  heterotrophic bacteria and fungi count showed no significance difference for the collection sites; but the coliform mean results for the three sites showed marked variation at 95% level (P>0.05). Identified bacteria, include: Staphylococcus aureus, E. coli, Bacillus sp., Klebsiella sp., whereas fungi are Penicillium sp., Aspergilusl sp., Fusarium violaceum, Biospora sp., Candida sp, Botryodioplodia sp., Alternania sp. This high level of microbial contamination can be traceable to handlers, and environment to which this fish is exposed during smoking and selling exercises, and considering the danger it portends to human health, public health and  food safety authorities should intensify their monitoring efforts towards controlling such contamination.Key words: Bacteria, Yeast, Mould, Smoked fish, Contamination

    A case of concomitant pulmonary tuberculosis and mucormycosis in an insulin-dependent diabetic patient

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    Conditions, where the patient's immune system is compromised are the main risk factor for mucormycosis. Approximately 23% of the world's population is estimated to have a latent Mycobacterium tuberculosis infection and more than 10 million new cases were estimated in 2017. Pulmonary mucormycosis and tuberculosis co-infections are very rare. We present the case of a 56-year-old insulin-dependent diabetic patient with a pulmonary mucormycosis and tuberculosis co-infection. While the patient did not suffer from ketoacidosis, she had poor glycemic control. A chest X-ray and a computed tomography showed nodular and cavitary lesions in both lungs. The patient was diagnosed through a biopsy of the bronchial mucosa and an RT-PCR for M. tuberculosis from bronchoalveolar lavage. The patient was treated with the recommended 4-drug regimen for TB (i.e. isoniazid, rifampin, pyrazinamide, and ethambutol); concurrently, amphotericin B deoxycholate was administered to treat the mucormycosis infection. Thirty days after initial hospital admission the patient underwent a lobectomy on the right lung. The case described here is only the sixth case reported in the literature of concomitant pulmonary tuberculosis and mucormycosis and the third case associated with a TB and mucormycosis co-infection involving an uncontrolled DM patient to survive

    The role of tool geometry in process damped milling

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    The complex interaction between machining structural systems and the cutting process results in machining instability, so called chatter. In some milling scenarios, process damping is a useful phenomenon that can be exploited to mitigate chatter and hence improve productivity. In the present study, experiments are performed to evaluate the performance of process damped milling considering different tool geometries (edge radius, rake and relief angles and variable helix/pitch). The results clearly indicate that variable helix/pitch angles most significantly increase process damping performance. Additionally, increased cutting edge radius moderately improves process damping performance, while rake and relief angles have a smaller and closely coupled effect

    An update on retinal prostheses

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    Retinal prostheses are designed to restore a basic sense of sight to people with profound vision loss. They require a relatively intact posterior visual pathway (optic nerve, lateral geniculate nucleus and visual cortex). Retinal implants are options for people with severe stages of retinal degenerative disease such as retinitis pigmentosa and age-related macular degeneration. There have now been three regulatory-approved retinal prostheses. Over five hundred patients have been implanted globally over the past 15 years. Devices generally provide an improved ability to localize high-contrast objects, navigate, and perform basic orientation tasks. Adverse events have included conjunctival erosion, retinal detachment, loss of light perception, and the need for revision surgery, but are rare. There are also specific device risks, including overstimulation (which could cause damage to the retina) or delamination of implanted components, but these are very unlikely. Current challenges include how to improve visual acuity, enlarge the field-of-view, and reduce a complex visual scene to its most salient components through image processing. This review encompasses the work of over 40 individual research groups who have built devices, developed stimulation strategies, or investigated the basic physiology underpinning retinal prostheses. Current technologies are summarized, along with future challenges that face the field

    Sociobiological Control of Plasmid copy number

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    Background:
All known mechanisms and genes responsible for the regulation of plasmid replication lie with the plasmid rather than the chromosome. It is possible therefore that there can be copy-up mutants. Copy-up mutants will have within host selective advantage. This would eventually result into instability of bacteria-plasmid association. In spite of this possibility low copy number plasmids appear to exist stably in host populations. We examined this paradox using a computer simulation model.

Model:
Our multilevel selection model assumes a wild type with tightly regulated replication to ensure low copy number. A mutant with slightly relaxed replication regulation can act as a “cheater” or “selfish” plasmid and can enjoy a greater within-host-fitness. However the host of a cheater plasmid has to pay a greater cost. As a result, in host level competition, host cell with low copy number plasmid has a greater fitness. Furthermore, another mutant that has lost the genes required for conjugation was introduced in the model. The non-conjugal mutant was assumed to undergo conjugal transfer in the presence of another conjugal plasmid in the host cell.

Results:
The simulatons showed that if the cost of carrying a plasmid was low, the copy-up mutant could drive the wild type to extinction or very low frequencies. Consequently, another mutant with a higher copy number could invade the first invader. This process could result into an increasing copy number. However above a certain copy number within-host selection was overcompensated by host level selection leading to a rock-paper-scissor (RPS) like situation. The RPS situation allowed the coexistence of high and low copy number plasmids. The non-conjugal “hypercheaters” could further arrest the copy numbers to a substantially lower level.

Conclusions:
These sociobiological interactions might explain the stability of copy numbers better than molecular mechanisms of replication regulation alone

    Non-universal minimal Z' models: present bounds and early LHC reach

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    We consider non-universal 'minimal' Z' models, whose additional U(1) charge is a non-anomalous linear combination of the weak hypercharge Y, the baryon number B and the partial lepton numbers (L_e, L_mu, L_tau), with no exotic fermions beyond three standard families with right-handed neutrinos. We show that the observed pattern of neutrino masses and mixing can be fully reproduced by a gauge-invariant renormalizable Lagrangian, and flavor-changing neutral currents in the charged lepton sector are suppressed by a GIM mechanism. We then discuss the phenomenology of some benchmark models. The electrophilic B-3L_e model is significantly constrained by electroweak precision tests, but still allows to fit the hint of an excess observed by CDF in dielectrons but not in dimuons. The muonphilic B-3L_mu model is very mildly constrained by electroweak precision tests, so that even the very early phase of the LHC can explore significant areas of parameter space. We also discuss the hadrophobic L_mu-L_tau model, which has recently attracted interest in connection with some puzzling features of cosmic ray spectra.Comment: 29 pages, 13 figure
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