1,085 research outputs found
Naphthalene-2,6-dicarbÂoxyÂlic acidâ1-methylÂpyrrolidin-2-one (1/2)
The asymmetric unit of the title compound, C12H8O4¡2C5H9NO, contains one half-molÂecule of naphthalene-2,6-dicarbÂoxyÂlic acid (NDA) and one molÂecule of 1-methylÂpyrrolidin-2-one (NMP): the NDA molecules lie on the crystallographic twofold rotation axes. In the crystal, the components are linked by strong OâHâŻO hydrogen bonds and CâHâŻO interÂactions
Transboundary Cooperation Improves Endangered Species Monitoring and Conservation Actions: A Case Study of the Global Population of Amur Leopards
Political borders and natural boundaries of wildlife populations seldom coincide, often to the detriment of conservation objectives. Transnational monitoring of endangered carnivores is rare, but is necessary for accurate population monitoring and coordinated conservation policies. We investigate the benefits of collaboratively monitoring the abundance and survival of the critically endangered Amur leopard, which occurs as a single transboundary population across China and Russia. Countryâspecific results overestimated abundance and were generally less precise compared to integrated monitoring estimates; the global population was similar in both years: 84 (70â108, 95% confidence interval). Uncertainty in countryâspecific annual survival estimates were approximately twice the integrated estimates of 0.82 (0.69â0.91, 95% confidence limits). This collaborative effort provided a better understanding of Amur leopard population dynamics, represented a first step in building trust, and lead to cooperative agreements to coordinate conservation policies
In Situ Proteolysis to Generate Crystals for Structure Determination: An Update
For every 100 purified proteins that enter crystallization trials, an average of 30 form crystals, and among these only 13â15 crystallize in a form that enables structure determination. In 2007, Dong et al reported that the addition of trace amounts of protease to crystallization trialsâin situ proteolysisâsignificantly increased the number of proteins in a given set that produce diffraction quality crystals. 69 proteins that had previously resisted structure determination were subjected to crystallization with in situ proteolysis and ten crystallized in a form that led to structure determination (14.5% success rate). Here we apply in situ proteolysis to over 270 new soluble proteins that had failed in the past to produce crystals suitable for structure determination. These proteins had produced no crystals, crystals that diffracted poorly, or produced twinned and/or unmanageable diffraction data. The new set includes yeast and prokaryotic proteins, enzymes essential to protozoan parasites, and human proteins such as GTPases, chromatin remodeling proteins, and tyrosine kinases. 34 proteins yielded deposited crystal structures of 2.8 Ă
resolution or better, for an overall 12.6% success rate, and at least ten more yielded well-diffracting crystals presently in refinement. The success rate among proteins that had previously crystallized was double that of those that had never before yielded crystals. The overall success rate is similar to that observed in the smaller study, and appears to be higher than any other method reported to rescue stalled protein crystallography projects
In Situ Proteolysis to Generate Crystals for Structure Determination: An Update
For every 100 purified proteins that enter crystallization trials, an average of 30 form crystals, and among these only 13â15 crystallize in a form that enables structure determination. In 2007, Dong et al reported that the addition of trace amounts of protease to crystallization trialsâin situ proteolysisâsignificantly increased the number of proteins in a given set that produce diffraction quality crystals. 69 proteins that had previously resisted structure determination were subjected to crystallization with in situ proteolysis and ten crystallized in a form that led to structure determination (14.5% success rate). Here we apply in situ proteolysis to over 270 new soluble proteins that had failed in the past to produce crystals suitable for structure determination. These proteins had produced no crystals, crystals that diffracted poorly, or produced twinned and/or unmanageable diffraction data. The new set includes yeast and prokaryotic proteins, enzymes essential to protozoan parasites, and human proteins such as GTPases, chromatin remodeling proteins, and tyrosine kinases. 34 proteins yielded deposited crystal structures of 2.8 Ă
resolution or better, for an overall 12.6% success rate, and at least ten more yielded well-diffracting crystals presently in refinement. The success rate among proteins that had previously crystallized was double that of those that had never before yielded crystals. The overall success rate is similar to that observed in the smaller study, and appears to be higher than any other method reported to rescue stalled protein crystallography projects
Threat-sensitive anti-predator defence in precocial wader, the northern lapwing Vanellus vanellus
Birds exhibit various forms of anti-predator behaviours to avoid reproductive failure, with mobbingâobservation, approach and usually harassment of a predatorâbeing one of the most commonly observed. Here, we investigate patterns of temporal variation in the mobbing response exhibited by a precocial species, the northern lapwing (Vanellus vanellus). We test whether brood age and self-reliance, or the perceived risk posed by various predators, affect mobbing response of lapwings. We quantified aggressive interactions between lapwings and their natural avian predators and used generalized additive models to test how timing and predator species identity are related to the mobbing response of lapwings. Lapwings diversified mobbing response within the breeding season and depending on predator species. Raven Corvus corax, hooded crow Corvus cornix and harriers evoked the strongest response, while common buzzard Buteo buteo, white stork Ciconia ciconia, black-headed gull Chroicocephalus ridibundus and rook Corvus frugilegus were less frequently attacked. Lapwings increased their mobbing response against raven, common buzzard, white stork and rook throughout the breeding season, while defence against hooded crow, harriers and black-headed gull did not exhibit clear temporal patterns. Mobbing behaviour of lapwings apparently constitutes a flexible anti-predator strategy. The anti-predator response depends on predator species, which may suggest that lapwings distinguish between predator types and match mobbing response to the perceived hazard at different stages of the breeding cycle. We conclude that a single species may exhibit various patterns of temporal variation in anti-predator defence, which may correspond with various hypotheses derived from parental investment theory
Resilience and physical and mental well-being in adults with and without HIV
Resilience has been related to improved physical and mental health, and is thought to improve with age. No studies have explored the relationship between resilience, ageing with HIV, and well-being. A cross sectional observational study performed on UK HIV positive (N = 195) and HIV negative adults (N = 130). Associations of both age and âtime diagnosed with HIVâ with resilience (RS-14) were assessed, and the association of resilience with depression, anxiety symptoms (PHQ-9 and GAD-7), and problems with activities of daily living (ADLs) (Euroqol 5D-3L). In a multivariable model, HIV status overall was not related to resilience. However, longer time diagnosed with HIV was related to lower resilience, and older age showed a non-significant trend towards higher resilience. In adults with HIV, high resilience was related to a lower prevalence of depression, anxiety, and problems with ADLs. It may be necessary to consider resilience when exploring the well-being of adults ageing with HIV
Biological-effective versus conventional dose volume histograms correlated with late genitourinary and gastrointestinal toxicity after external beam radiotherapy for prostate cancer: a matched pair analysis
BACKGROUND: To determine whether the dose-volume histograms (DVH's) for the rectum and bladder constructed using biological-effective dose (BED-DVH's) better correlate with late gastrointestinal (GI) and genitourinary (GU) toxicity after treatment with external beam radiotherapy for prostate cancer than conventional DVH's (C-DVH's). METHODS: The charts of 190 patients treated with external beam radiotherapy with a minimum follow-up of 2 years were reviewed. Six patients (3.2%) were found to have RTOG grade 3 GI toxicity, and similarly 6 patients (3.2%) were found to have RTOG grade 3 GU toxicity. Average late C-DVH's and BED-DVH's of the bladder and rectum were computed for these patients as well as for matched-pair control patients. For each matched pair the following measures of normalized difference in the DVH's were computed: (a) δ(AUC )= (Area Under Curve [AUC] in grade 3 patient â AUC in grade 0 patient)/(AUC in grade 0 patient) and (b) δ(V60 )= (Percent volume receiving = 60 Gy [V60] in grade 3 patient â V60 in grade 0 patient)/(V60 in grade 0 patient). RESULTS: As expected, the grade 3 curve is to the right of and above the grade 0 curve for all four sets of average DVH's â suggesting that both the C-DVH and the BED-DVH can be used for predicting late toxicity. δ(AUC )was higher for the BED-DVH's than for the C-DVH's â 0.27 vs 0.23 (p = 0.036) for the rectum and 0.24 vs 0.20 (p = 0.065) for the bladder. δ(V60 )was also higher for the BED-DVH's than for the C-DVH's â 2.73 vs 1.49 for the rectum (p = 0.021) and 1.64 vs 0.71 (p = 0.021) for the bladder. CONCLUSIONS: When considering well-established dosimetric endpoints used in evaluating treatment plans, BED-DVH's for the rectum and bladder correlate better with late toxicity than C-DVH's and should be considered when attempting to minimize late GI and GU toxicity after external beam radiotherapy for prostate cancer
Search for the pentaquark in the reaction
A search for the \thp in the reaction was completed
using the CLAS detector at Jefferson Lab. A study of the same reaction,
published earlier, reported the observation of a narrow \thp resonance. The
present experiment, with more than 30 times the integrated luminosity of our
earlier measurement, does not show any evidence for a narrow pentaquark
resonance. The angle-integrated upper limit on \thp production in the mass
range of 1.52 to 1.56 GeV/c for the reaction is
0.3 nb (95% CL). This upper limit depends on assumptions made for the mass and
angular distribution of \thp production. Using \lamstar production as an
empirical measure of rescattering in the deuteron, the cross section upper
limit for the elementary reaction is estimated to be
a factor of 10 higher, {\it i.e.}, nb (95% CL).Comment: 5 figures, submitted to PRL, revised for referee comment
Photodisintegration of He into p+t
The two-body photodisintegration of He into a proton and a triton has
been studied using the CEBAF Large-Acceptance Spectrometer (CLAS) at Jefferson
Laboratory. Real photons produced with the Hall-B bremsstrahlung-tagging system
in the energy range from 0.35 to 1.55 GeV were incident on a liquid He
target. This is the first measurement of the photodisintegration of He
above 0.4 GeV. The differential cross sections for the He
reaction have been measured as a function of photon-beam energy and
proton-scattering angle, and are compared with the latest model calculations by
J.-M. Laget. At 0.6-1.2 GeV, our data are in good agreement only with the
calculations that include three-body mechanisms, thus confirming their
importance. These results reinforce the conclusion of our previous study of the
three-body breakup of He that demonstrated the great importance of
three-body mechanisms in the energy region 0.5-0.8 GeV .Comment: 13 pages submitted in one tgz file containing 2 tex file and 22
postscrip figure
The Quiet Revolution and the Family: Gender Composition of Tertiary Education and Early Fertility Patterns
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