62 research outputs found
Opening of a pseudogap in a quasi-two dimensional superconductor due to critical thermal fluctuations
We examine the role of the anisotropy of superconducting critical thermal
fluctuations in the opening of a pseudogap in a quasi-two dimensional
superconductor such as a cuprate-oxide high-temperature superconductor. When
the anisotropy between planes and their perpendicular axis is large enough and
its superconducting critical temperature T_c is high enough, the fluctuations
are much developed in its critical region so that lifetime widths of
quasiparticles are large and the energy dependence of the selfenergy deviates
from that of Landau's normal Fermi liquids. A pseudogap opens in such a
critical region because quasiparticle spectra around the chemical potential are
swept away due to the large lifetime widths. The pseudogap never smoothly
evolves into a superconducting gap; it starts to open at a temperature higher
than T_c while the superconducting gap starts to open just at T_c. When T_c is
rather low but the ratio of varepsilon_G(0)/k_BT_c, with varepsilon_G(0) the
superconducting gap at T=0K and k_B the Boltzmann constant, is much larger than
a value about 4 according to the mean-field theory, the pseudogap must be
closing as temperature T approaches to the low T_c because thermal fluctuations
become less developed as T decreases. Critical thermal fluctuations cannot
cause the opening of a prominent pseudogap in an almost isotropic three
dimensional superconductor, even if its T_c is high.Comment: 25 pages, 5 figures (14 subfigures
In vitro multistage malaria transmission blocking activity of selected malaria box compounds
Purpose: Continuous efforts into the discovery and development of new antimalarials are required to face the emerging resistance of the parasite to available treatments. Thus, new effective drugs, ideally able to inhibit the Plasmodium life-cycle stages that cause the disease as well as those responsible for its transmission, are needed. Eight compounds from the Medicines for Malaria Venture (MMV) Malaria Box, potentially interfering with the parasite polyamine biosynthesis were selected and assessed in vitro for activity against malaria transmissible stages, namely mature gametocytes and early sporogonic stages. Methods: Compound activity against asexual blood stages of chloroquine-sensitive 3D7 and chloroquine-resistant W2 strains of Plasmodium falciparum was tested measuring the parasite lactate dehydrogenase activity. The gametocytocidal effect was determined against the P. falciparum 3D7elo1-pfs16-CBG99 strain with a luminescent method. The murine P. berghei CTRP.GFP strain was employed to assess compounds activities against early sporogonic stage development in an in vitro assay simulating mosquito midgut conditions. Results: Among the eight tested molecules, MMV000642, MMV000662 and MMV006429, containing a 1,2,3,4-tetrahydroisoquinoline-4-carboxamide chemical skeleton substituted at N-2, C-3 and C-4, displayed multi-stage activity. Activity against asexual blood stages of both strains was confirmed with values of IC50 (50% inhibitory concentration) in the range of 0.07\u20130.13 \ub5M. They were also active against mature stage V gametocytes with IC50 values below 5 \ub5M (range: 3.43\u20134.42 \ub5M). These molecules exhibited moderate effects on early sporogonic stage development, displaying IC50 values between 20 and 40 \ub5M. Conclusion: Given the multi-stage, transmission-blocking profiles of MMV000642, MMV000662, MMV006429, and their chemical characteristics, these compounds can be considered worthy for further optimisation toward a TCP5 or TCP6 target product profile proposed by MMV for transmission-blocking antimalarials
The determination of safety of Muhanse M4®, a traditional herbal preparation used to treat HIV/AIDS-related conditions and diseases in Tanzania
Muhanse M4® is a traditional herbal preparation that has been in use in Tanzania for the past 17 years to improve the quality of life among people living with HIV/AIDS. This study was carried out to determine the safety of the extract Muhanse M4® in animal models. The qualitative test to identify alkaloids and saponins compounds was carried out. The toxicity tests in Swiss albino mice and rats were done according to WHO guidelines of 1993. Muhanse M4® was dissolved homogeneously in distilled water and was administered both intraperitonially and orally for 14 days for sub-acute test and 24 hours for acute test. Qualitatively, the extract was found to contain no alkaloids or saponins. In rats intraperitoneal doses that caused 100% lethality were 758.55 mg/kg and 553.7415mg/kg when administered singly and repeated, respectively. Single oral dose up to 3034.200mg/kg did not cause any death in the tested mice or rats. NOEL during intraperitoneal repeated doses for liver in rats was 424.788mg/kg, and NOAEL was 455.130mg/kg. In rats LD10%, LD50% and LD100% were 485.472mg/kg, 526.4337mg/kg and 553.7415mg/kg, respectively. In conclusion, Muhanse M4® extract is considered to be safe in laboratory animals. Keywords: Muhanse M4®, toxicity, medicinal plants, traditional medicine, HIV/AIDS Tanzania Health Research Bulletin Vol. 7(3) 2005: 168-17
Screening of Mycobacterium avium subsp. paratuberculosis mutants for attenuation in a bovine monocyte-derived macrophage model
Vaccination remains a major tool for prevention and progression of Johne’s disease, a chronic enteritis of ruminants worldwide. Currently there is only one licensed vaccine within the United States and two vaccines licensed internationally against Johne’s disease. All licensed vaccines reduce fecal shedding of Mycobacterium avium subsp. paratuberculosis (MAP) and delay disease progression. However, there are no available vaccines that prevent disease onset. A joint effort by the Johne’s Disease Integrated Program (JDIP), a USDA-funded consortium, and USDA—APHIS/VS sought to identify transposon insertion mutant strains as vaccine candidates in part of a three phase study. The focus of the Phase I study was to evaluate MAP mutant attenuation in a well-defined in vitro bovine monocyte-derived macrophage (MDM) model. Attenuation was determined by colony forming unit (CFUs) counts and slope estimates. Based on CFU counts alone, the MDM model did not identify any mutant that significantly differed from the wild-type control, MAP K-10. Slope estimates using mixed models approach identified six mutants as being attenuated. These were enrolled in protection studies involving murine and baby goat vaccination-challenge models. MDM based approach identified trends in attenuation but this did not correlate with protection in a natural host model. These results suggest the need for alternative strategies for Johne’s disease vaccine candidate screening and evaluation
Hypercatecholaminaemia in stress urinary incontinence and its pathogenetic treatment perspectives: an experimental non-randomised study
Background. Urinary incontinence is associated with chronic psycho-emotional stress. Stress management should be part of a comprehensive treatment for urinary incontinence.Objectives. An assessment of hypercatecholaminaemia severity and dynamics in repeated courses of TES therapy for stress urinary incontinence.Methods. A total of 100 stress urinary incontinence patients were divided between a comparison and two main cohorts. Main cohort 1 (n = 30) received a modern standard treatment in combination with TES therapy. TES therapy was performed in three courses (1 session per day for 7 days): course 1 on admission, course 2 in 3 months after course 1, course 3 in 6 months after course 1. Main cohort 2 (n = 40) received a modern standard treatment in combination with two short courses of TES-therapy (2 sessions per day for 7 days): course 1 on admission, course 2 in 6 months after course 1. The comparison cohort (n = 30) only had standard treatment. Catecholamine concentrations were assessed over time in each cohort.Results. Catecholamine concentrations were >2 times higher before treatment in all cohorts vs. healthy volunteers. The comparison cohort revealed adrenaline and noradrenaline concentrations 71.2% (p < 0.05) and 84.0% (p < 0.05) higher vs. healthy volunteers, respectively, by month 6 of the trial. Main cohort 1 had the concentrations of adrenaline and noradrenaline 2.1 (p < 0.05) and 1.5 (p < 0.05) times higher, respectively, vs. healthy volunteers. Main cohort 2 showed an adrenaline concentration 12.5% (p < 0.05) and noradrenaline — 2.4% higher (p = 0.15) vs. healthy volunteers.Conclusion. TES therapy affects urinary incontinence hypercatecholaminaemia, demonstrating a favourable homeostatic impact on neuroimmunoendocrine regulation
Identification of Sero-Diagnostic Antigens for the Early Diagnosis of Johne’s Disease using MAP Protein Microarrays
Considerable effort has been directed toward controlling Johne’s disease (JD), a chronic granulomatous intestinal inflammatory disease caused by Mycobacterium avium subsp. paratuberculosis (MAP) in cattle and other ruminants. However, progress in controlling the spread of MAP infection has been impeded by the lack of reliable diagnostic tests that can identify animals early in the infection process and help break the transmission chain. To identify reliable antigens for early diagnosis of MAP infection, we constructed a MAP protein array with 868 purified recombinant MAP proteins, and screened a total of 180 well-characterized serum samples from cows assigned to 4 groups based on previous serological and fecal test results: negative low exposure (NL, n = 30); negative high exposure (NH, n = 30); fecal- positive, ELISA-negative (F + E−, n = 60); and both fecal- and ELISA-positive (F + E+, n = 60). The analyses identified a total of 49 candidate antigens in the NH, F + E−, and F + E+ with reactivity compared with the NL group (p \u3c 0.01), a majority of which have not been previously identified. While some of the antigens were identified as reactive in only one of the groups, others showed reactivity in multiple groups, including NH (n = 28), F + E− (n = 26), and F + E+ (n = 17) groups. Using combinations of top reactive antigens in each group, the results reveal sensitivities of 60.0%, 73.3%, and 81.7% in the NH, F + E−, and F + E+, respectively at 90% specificity, suggesting that early detection of infection in animals may be possible and enable better opportunities to reduce within herd transmission that may be otherwise missed by traditional serological assays that are biased towards more heavily infected animals. Together, the results suggest that several of the novel candidate antigens identified in this study, particularly those that were reactive in the NH and F + E− groups, have potential utility for the early sero-diagnosis of MAP infection
Forest Protection
Forest protection is a practice of preventing and controlling both biotic and abiotic agents, which affect forests and their associated products. There are two agents responsible for tree injury and diseases namely non-pathogenic and pathogenic, they are also known as abiotic and biotic respectively. Non-pathogenic agents include fire, climatic conditions (e.g. wind, drought, rain, and heat), soil conditions and air pollutants. Pathogenic agents cause
diseases and they include viruses, bacteria, fungi, mycoplasmas (e.g. protozoa and algae); parasitic plants (e.g. mistletoes), nematodes, arthropods (e.g. insects), birds and mammals. Forest fire, pathology and entomology are discussed in detail in this chapter
Forests and Climate Change Mitigation
Forest ecosystems are increasingly being recognized for their important role in climate change mitigation because of their ability to regulate the carbon cycle. As a result, national and global initiatives such as afforestation/reforestation under CDM and REDD+ have been initiated to enhance the role of forests in climate change mitigation. Understanding the relationship between forests and climate change mitigation is necessary to enable the meaningful participation of forest practitioners in forest carbon projects and programmes. This chapter explores and highlights aspects of climate change mitigation as linked to forestry by explaining the meaning of climate change mitigation while also introducing various types of GHG sinks. Also covered in the chapter are relevant national strategies and policies in addition to available forest and non-forest based options for participating in mitigation activities. The chapter ends by giving an overview of M & E methods available for mitigation projects
The regeneration dynamics of Miombo tree species in Sub-Saharan Africa
African Journal of Ecology and Ecosystems, 2019; 6 (5): 001-016Miombo woodlands support livelihoods of more than 100 million rural and urban dwellers by providing them with a wide range of products and services. Concurrently, Miombo shelters more than 10000 plants and animal species majority of which are endemic. However, overexploitation of Miombo through trees cutting for charcoal, firewood, tobacco curing, farmlands expansion, and wildfires have led to deforestation and forest degradation accompanied by multiple negative effects on human livelihoods. Regeneration as a survival strategy after disturbance is an important plant functional trait for its sustainability. This paper reviewed the regeneration dynamics of Miombo tree species. The aim was to explore regeneration methods, factors affecting regeneration
in Miombo ecosystem and proposes the most promising disturbance-dependent regeneration method. Information for this study was obtained by the synthesis of academic articles obtained through standard literature search performed using multiple electronic databases. Studies in Sub-Saharan Africa have demonstrated the vital role of natural regeneration in the sustainable and post-disturbance management of Miombo woodlands. Conclusively, Miombo regenerates sexually through seedlings and vegetatively propagated through root suckers and coppicing. However, vegetative propagation is highly recommended as it offers maximum regeneration with fast growth rate contributing to the rapid recovery of disturbed Miombo woodland ecosystem.Tanzania Forest Conservation Group (TFCG) and MJUMIT
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