499 research outputs found
Molecular phylogenetic analysis of Arenaria (Caryophyllaceae: tribe Arenarieae) and its allies inferred from nuclear DNA internal transcribed spacer and plastid DNA rps16 sequences
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/112194/1/boj12293.pd
First Detection of Nosema ceranae, a Microsporidian Protozoa of European Honeybees (Apis mellifera) In Iran
Background: Nosemosis of European honey bee (Apis mellifera) is present in bee colonies worldÂwide. Until recently, Nosema apis had been regarded as the causative agent of the disease, that causes heavy economic losses in apicultures. Nosema ceranae is an emerging microsporidian paraÂsite of European honeybees, A. mellifera, but its distribution is not well known. Previously, nosemosis in honeybees in Iran was attributed exclusively to N. apis.Methods: Six Nosema positive samples (determined from light microscopy of spores) of adult worker bees from one province of Iran (Savadkouh- Mazandaran, northern Iran) were tested to determine Nosema species using previously- developed PCR primers of the 16 S rRNA gene. As it is difficult to distinguish N. ceranae and N. apis morphologically, a PCR assay based on 16 S ribosomal RNA has been used to differentiate N. apis and N. ceranae.Results: Only N. ceranae was found in all samples, indicating that this species present in Iran apiarÂies.Conclusion: This is the first report of N. ceranae in colonies of A. mellifera in Iran. It seems that intensive surveys are needed to determine the distribution and prevalence of N. ceranae in differÂent regions of Iran
BLUF Domain Function Does Not Require a Metastable Radical Intermediate State
BLUF
(blue light using flavin) domain proteins are an important
family of blue light-sensing proteins which control a wide variety
of functions in cells. The primary light-activated step in the BLUF
domain is not yet established. A number of experimental and theoretical
studies points to a role for photoinduced electron transfer (PET)
between a highly conserved tyrosine and the flavin chromophore to
form a radical intermediate state. Here we investigate the role of
PET in three different BLUF proteins, using ultrafast broadband transient
infrared spectroscopy. We characterize and identify infrared active
marker modes for excited and ground state species and use them to
record photochemical dynamics in the proteins. We also generate mutants
which unambiguously show PET and, through isotope labeling of the
protein and the chromophore, are able to assign modes characteristic
of both flavin and protein radical states. We find that these radical
intermediates are not observed in two of the three BLUF domains studied,
casting doubt on the importance of the formation of a population of
radical intermediates in the BLUF photocycle. Further, unnatural amino
acid mutagenesis is used to replace the conserved tyrosine with fluorotyrosines,
thus modifying the driving force for the proposed electron transfer
reaction; the rate changes observed are also not consistent with a
PET mechanism. Thus, while intermediates of PET reactions can be observed
in BLUF proteins they are not correlated with photoactivity, suggesting
that radical intermediates are not central to their operation. Alternative
nonradical pathways including a keto–enol tautomerization induced
by electronic excitation of the flavin ring are considered
Prospects for Probing the Spacetime of Sgr A* with Pulsars
The discovery of radio pulsars in compact orbits around Sgr A* would allow an
unprecedented and detailed investigation of the spacetime of the supermassive
black hole. This paper shows that pulsar timing, including that of a single
pulsar, has the potential to provide novel tests of general relativity, in
particular its cosmic censorship conjecture and no-hair theorem for rotating
black holes. These experiments can be performed by timing observations with 100
micro-second precision, achievable with the Square Kilometre Array for a normal
pulsar at frequency above 15 GHz. Based on the standard pulsar timing
technique, we develop a method that allows the determination of the mass, spin,
and quadrupole moment of Sgr A*, and provides a consistent covariance analysis
of the measurement errors. Furthermore, we test this method in detailed mock
data simulations. It seems likely that only for orbital periods below ~0.3 yr
is there the possibility of having negligible external perturbations. For such
orbits we expect a ~10^-3 test of the frame dragging and a ~10^-2 test of the
no-hair theorem within 5 years, if Sgr A* is spinning rapidly. Our method is
also capable of identifying perturbations caused by distributed mass around Sgr
A*, thus providing high confidence in these gravity tests. Our analysis is not
affected by uncertainties in our knowledge of the distance to the Galactic
center, R0. A combination of pulsar timing with the astrometric results of
stellar orbits would greatly improve the measurement precision of R0.Comment: 12 pages, 10 Figures, accepted for publication in Ap
The ecological diversity of vegetation within Urban Parks in the Dabrowski Basin (southern Poland)
The aim of this work is to present the diversity of flora in terms of ecological requirements. The research was
conducted in the area of two urban parks in the area of two cities in southern Poland: Bedzin and Czeladz. These parks were
established in different historical periods, and were planned (and are managed) differently. The results of the investigation
have shown that the occurrence of 192 vascular species has been observed in the Gora Zamkowa (Castle Hill) Park, while in
the Grabek park, 334 such species are known to exist. Such disparity is the result of the occurrence of micro-habitats and of
the differences between the ways the two parks are managed. It is also due to these parks’ different functions. In the first case,
the park area is protected by law. In the latter case, human activity has created a new ecological niche for organisms with a
high degree of ecological tolerance. Based on the ecological values, the following groups of plants were distinguished: saxifrages
grasslands, xerothermic grasslands, beech forests, alder forests and artificial planted trees. Analysis has shown that urban
parks are potential places for growth various type of vegetation and also for increasing biodiversity, and can constitute
particularly important hotspots for biodiversity in the cityscape, even if their primary role is recreational. As the study shows,
the environment of a highly urbanized and industrialized region can also have a positive influence on ecological and floristic
diversity
The GstLAL Search Analysis Methods for Compact Binary Mergers in Advanced LIGO's Second and Advanced Virgo's First Observing Runs
After their successful first observing run (September 12, 2015 - January 12,
2016), the Advanced LIGO detectors were upgraded to increase their sensitivity
for the second observing run (November 30, 2016 - August 26, 2017). The
Advanced Virgo detector joined the second observing run on August 1, 2017. We
discuss the updates that happened during this period in the GstLAL-based
inspiral pipeline, which is used to detect gravitational waves from the
coalescence of compact binaries both in low latency and an offline
configuration. These updates include deployment of a zero-latency whitening
filter to reduce the over-all latency of the pipeline by up to 32 seconds,
incorporation of the Virgo data stream in the analysis, introduction of a
single-detector search to analyze data from the periods when only one of the
detectors is running, addition of new parameters to the likelihood ratio
ranking statistic, increase in the parameter space of the search, and
introduction of a template mass-dependent glitch-excision thresholding method.Comment: 12 pages, 7 figures, to be submitted to Phys. Rev. D, comments
welcom
Influence of heat input on microstructure and mechanical properties of gas tungsten arc welded HSLA S500MC steel joints
High-strength low alloy (HSLA) S500MC steel is widely used for chassis components, structural parts, and pressure vessels. In this study, the effects of heat input during automatic gas tungsten arc welding (GTAW) on microstructure and mechanical properties of thermomechanically controlled processed (TMP) S500MC steel were investigated. A butt joint configuration was used, and welding was performed in autogenous mode. Six different levels of heat input namely 1.764 kJ/mm, 1.995 kJ/mm, 2.035 kJ/mm, 2.132 kJ/mm, 2.229 kJ/mm, and 2.33 kJ/mm were considered. Microstructural investigations revealed a different microstructure than base metal in the fusion zone (FZ) of all welded joints which was most likely due to a lath martensitic microstructure surrounded by retained austenite. With increased heat input, the amount of retained austenite and the size of packets increased. In the heat-affected zone (HAZ), two distinct regions of coarse grain (CG-HAZ) and fine grain (FG-HAZ) were observed. Due to the presence of carbides in the HAZ, mostly a martensitic microstructure with smaller packets, compared to FZ, was formed. By increasing the heat input and through the dissolution of carbides, the dimension of packets increased. Due to microstructural changes and grain growth, in both the FZ and the HAZ, the mechanical properties produced by TMP were lost in these regions. However, failure occurred in the base metal of all samples with a maximum tensile strength of 690 MPa. Thus, tensile strength in the weld zone and HAZ were higher than the base metal even for the highest heat input indicating the formation of a good joint between S500MC plates with GTAW, regardless of heat input
The translocator protein (TSPO) is prodromal to mitophagy loss in neurotoxicity
Dysfunctional mitochondria characterise Parkinson's Disease (PD). Uncovering etiological molecules, which harm the homeostasis of mitochondria in response to pathological cues, is therefore pivotal to inform early diagnosis and therapy in the condition, especially in its idiopathic forms. This study proposes the 18 kDa Translocator Protein (TSPO) to be one of those. Both in vitro and in vivo data show that neurotoxins, which phenotypically mimic PD, increase TSPO to enhance cellular redox-stress, susceptibility to dopamine-induced cell death, and repression of ubiquitin-dependent mitophagy. TSPO amplifies the extracellular signal-regulated protein kinase 1 and 2 (ERK1/2) signalling, forming positive feedback, which represses the transcription factor EB (TFEB) and the controlled production of lysosomes. Finally, genetic variances in the transcriptome confirm that TSPO is required to alter the autophagy-lysosomal pathway during neurotoxicity
National Spinal Cord Injury Registry of Iran (NSCIR-IR) � a critical appraisal of its strengths and weaknesses
The National Spinal Cord Injury Registry of Iran (NSCIR-IR) is a not-for-profit, hospital-based, and prospective observational registry that appraises the quality of care, long-term outcomes and the personal and psychological burden of traumatic spinal cord injury in Iran. Benchmarking validity in every registry includes rigorous attention to data quality. Data quality assurance is essential for any registry to make sure that correct patients are being enrolled and that the data being collected are valid. We reviewed strengths and weaknesses of the NSCIR-IR while considering the methodological guidelines and recommendations for efficient and rational governance of patient registries. In summary, the steering committee, funded and maintained by the Ministry of Health and Medical Education of Iran, the international collaborations, continued staff training, suitable data quality, and the ethical approval are considered to be the strengths of the registry, while limited human and financial resources, poor interoperability with other health systems, and time-consuming processes are among its main weaknesses. © 2019 Chinese Medical Associatio
Exact Black Holes and Universality in the Backreaction of non-linear Sigma Models with a potential in (A)dS4
The aim of this paper is to construct accelerated, stationary and
axisymmetric exact solutions of the Einstein theory with self interacting
scalar fields in (A)dS4. To warm up, the backreaction of the (non)-minimally
coupled scalar field is solved, the scalar field equations are integrated and
all the potentials compatible with the metric ansatz and Einstein gravity are
found. With these results at hand the non-linear sigma model is tackled. The
scalar field Lagrangian is generic; neither the coupling to the curvature,
neither the metric in the scalar manifold nor the potential, are fixed ab
initio. The unique assumption in the analysis is the metric ansatz: it has the
form of the most general Petrov type D vacuum solution of general relativity;
it is a a cohomogeneity two Weyl rescaling of the Carter metric and therefore
it has the typical Plebanski-Demianski form with two arbitrary functions of one
variable and one arbitrary functions of two variables. It is shown, by an
straightforward manipulation of the field equations, that the metric is
completely integrable without necessity of specifiying anything in the scalar
Lagrangian. This results in that the backreaction of the scalar fields, within
this class of metrics, is universal. The metric functions generically show an
explicit dependence on a dynamical exponent that allows to smoothly connect
this new family of solutions with the actual Plebanski-Demianski spacetime. The
remaining field equations imply that the scalar fields follow geodesics in the
scalar manifold with an affine parameter given by a non-linear function of the
spacetime coordinates and define the on-shell form of the potential plus a
functional equation that it has to satisfy. Finally, a general family of (A)dS4
static hairy black holes is explicitly constructed and its properties are
outlined.Comment: Several typos correcte
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