459 research outputs found
Effective-Lagrangian approach to gamma gamma --> WW; II: Results and comparison with e+e- --> WW
We present a study of anomalous electroweak gauge-boson couplings which can
be measured in e+e- and gamma gamma collisions at a future linear collider like
ILC. We consider the gauge-boson sector of a locally SU(2) x U(1) invariant
effective Lagrangian with ten dimension-six operators added to the Lagrangian
of the Standard Model. These operators induce anomalous three- and
four-gauge-boson couplings and an anomalous gamma gamma H coupling. We
calculate the reachable sensitivity for the measurement of the anomalous
couplings in gamma gamma --> WW. We compare these results with the reachable
precision in the reaction e+e- --> WW on the one hand and with the bounds that
one can get from high-precision observables in Z decays on the other hand. We
show that one needs both the e+e- and the gamma gamma modes at an ILC to
constrain the largest possible number of anomalous couplings and that the
Giga-Z mode offers the best sensitivity for certain anomalous couplings.Comment: 25 pages, 1 figure, 7 tables, comments, references and a table added;
to appear in EPJ
Infectivity of Cryptosporidium parvum genotype I in conventionally reared piglets and lambs
Parasites of the genus Cryptosporidium are intracellular parasites that occur throughout the animal kingdom and have been reported in many species of mammals, including human. Most infections in humans are caused by two C. parvum genotypes, genotype I and genotype II; these are the human and the bovine (zoonotic) genotypes, respectively. Successful experimental infection of Cryptosporidium parvum genotype I "human genotype" is described in four conventionally reared piglets and in a lamb. The inoculum was originally obtained from two diarrheic children, and the Cryptosporidium genotypes were determined by PCR and rDNA sequencing. The infective dose was between 106 and 2×106oocysts. No clinical signs were observed in the infected animals, except in a piglet that showed watery diarrhea. The oocyst shedding period in positive animals ranged between 4 and 10 days. Histopathologic examination of the gastrointestinal tract of two positive piglets revealed shortening of the villi and denudation of the villous tips of the jejunum. In one piglet, the colon mucosa revealed numerous Cryptosporidium oocysts. The storage time of the inocula (≤3 weeks in PBS at 4°C) and the age of the animal (newborn) were important for the successful induction of infectio
Human and animal health on three continents--a biography of the early life of Karl Friedrich Meyer (1884-1974)
Karl Friedrich Meyer (KF) was born and educated as a veterinarian in Europe; he researched infectious diseases in Europe, South Africa and the United States. He is one of the true forefathers of the 'one health-one medicine' concept. The broad scope of his research covered botulism, leptospirosis, brucellosis, plague, ornithosis, Western equine encephalitis, mussel poisoning and clostridia. This manuscript adds some more details of his early biography
A GIS-based Approach for Modeling the Spatial and Temporal Development of Night-time Lights
One of the few directly observable indicators of human activity in spatially explicit form are night-time satellite imagery data. Nocturnal lighting can be regarded as one of the defining features of concentrated human activity, such as flaring of natural gas in oil field
Ovine enzootic abortion (OEA): Antibody response in vaccinated sheep compared to naturally infected sheep
Deer as a potential wildlife reservoir for Parachlamydia species.
Wildlife populations represent an important reservoir for emerging pathogens and trans-boundary livestock diseases. However, detailed information relating to the occurrence of endemic pathogens such as those of the order Chlamydiales in such populations is lacking. During the hunting season of 2008, 863 samples (including blood, conjunctival swabs, internal organs and faeces) were collected in the Eastern Swiss Alps from 99 free-living red deer (Cervus elaphus) and 64 free-living roe deer (Capreolus capreolus) and tested using ELISA, PCR and immunohistochemistry for members of the family Chlamydiaceae and the genus Parachlamydia. Parachlamydia spp. were detected in the conjunctival swabs, faeces and internal organs of both species of deer (2.4% positive, with a further 29.5% inconclusive). The very low occurrence of Chlamydiaceae (2.5%) was in line with serological data (0.7% seroprevalence for Chlamydia abortus). Further investigations are required to elucidate the zoonotic potential, pathogenicity, and distribution of Parachlamydia spp. in wild ruminants
Chlamydiosis in British Garden Birds (2005–2011): Retrospective Diagnosis and Chlamydia psittaci Genotype Determination
The significance of chlamydiosis as a cause of mortality in wild passerines (Order Passeriformes), and the role of these birds as a potential source of zoonotic Chlamydia psittaci infection, is unknown. We reviewed wild bird mortality incidents (2005–2011). Where species composition or post-mortem findings were indicative of chlamydiosis, we examined archived tissues for C. psittaci infection using PCR and ArrayTube Microarray assays. Twenty-one of 40 birds tested positive: 8 dunnocks (Prunella modularis), 7 great tits (Parus major), 3 blue tits (Cyanistes caeruleus), 2 collared doves (Streptopelia decaocto, Order Columbiformes), and 1 robin (Erithacus rubecula). Chlamydia psittaci genotype A was identified in all positive passerines and in a further three dunnocks and three robins diagnosed with chlamydiosis from a previous study. Two collared doves had genotype E. Ten of the 21 C. psittaci-positive birds identified in the current study had histological lesions consistent with chlamydiosis and co-localizing Chlamydia spp. antigens on immunohistochemistry. Our results indicate that chlamydiosis may be a more common disease of British passerines than was previously recognized. Wild passerines may be a source of C. psittaci zoonotic infection, and people should be advised to take appropriate hygiene precautions when handling bird feeders or wild birds
Pulmonary arterial lesions in new world camelids in association with dicrocoelium dendriticum and fasciola hepatica infection
In Switzerland, dicrocoeliasis is regarded as the most significant parasitic infection of llamas and alpacas. Fasciola hepatica infestation is also a problem but less common. The aim of the present retrospective study was to evaluate the lungs of New World camelids (NWCs) for evidence of arterial hypertension in association with liver changes due to liver fluke infestation. The lungs of 20 llamas and 20 alpacas with liver fluke infestation were histologically evaluated. The hematoxylin and eosin and van Gieson (VG)-elastica stains as well as immunohistology for the expression of α-smooth muscle actin (α-SMA) were used to visualize the structures of arterial walls. Parasitology of fecal matter (11 llamas and 17 alpacas) confirmed that most of these animals were infested with both Dicrocoelium dendriticum and other gastrointestinal parasites. In most cases (10/12 llamas, 4/6 alpacas), liver enzyme activity in serum was elevated. Histologically, arteries in the lungs of 9 of 20 llamas (45%) and 3 of 20 alpacas (15%) showed severe intimal and adventitial and slight to moderate medial thickening, which was confirmed with α-SMA and VG-elastica staining. All animals exhibited typical liver changes, such as fibrosis and biliary hyperplasia, in association with the presence of liver flukes. This study shows that liver flukes can induce proliferative changes in lung arteries in NWCs that resemble those seen with pulmonary arterial hypertension due to liver parasites in humans. However, the degree of liver fluke infestation was not correlated with the extent of liver damage, or with the amount of thoracic or abdominal effusion or pulmonary arterial changes
Extracting synaptic conductances from single membrane potential traces
In awake animals, the activity of the cerebral cortex is highly complex, with
neurons firing irregularly with apparent Poisson statistics. One way to
characterize this complexity is to take advantage of the high interconnectivity
of cerebral cortex and use intracellular recordings of cortical neurons, which
contain information about the activity of thousands of other cortical neurons.
Identifying the membrane potential (Vm) to a stochastic process enables the
extraction of important statistical signatures of this complex synaptic
activity. Typically, one estimates the total synaptic conductances (excitatory
and inhibitory) but this type of estimation requires at least two Vm levels and
therefore cannot be applied to single Vm traces. We propose here a method to
extract excitatory and inhibitory conductances (mean and variance) from single
Vm traces. This "VmT method" estimates conductance parameters using maximum
likelihood criteria, under the assumption are that synaptic conductances are
described by Gaussian stochastic processes and are integrated by a passive
leaky membrane. The method is illustrated using models and is tested on
guinea-pig visual cortex neurons in vitro using dynamic-clamp experiments. The
VmT method holds promises for extracting conductances from single-trial
measurements, which has a high potential for in vivo applications.Comment: Neuroscience (in press
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