2,741 research outputs found
Universal conductance fluctuations in three dimensional metallic single crystals of Si
In this paper we report the measurement of conductance fluctuations in single
crystals of Si made metallic by heavy doping (n \approx 2-2.5n_c, n_c being
critical composition at Metal-Insulator transition). Since all dimensions (L)
of the samples are much larger than the electron phase coherent length L_\phi
(L/L_\phi \sim 10^3), our system is truly three dimensional. Temperature and
magnetic field dependence of noise strongly indicate the universal conductance
fluctuations (UCF) as predominant source of the observed magnitude of noise.
Conductance fluctuations within a single phase coherent region of L_\phi^3 was
found to be saturated at \approx (e^2/h)^2. An accurate
knowledge of the level of disorder, enables us to calculate the change in
conductance \delta G_1 due to movement of a single scatterer as \delta G_1 \sim
e^2/h, which is \sim 2 orders of magnitude higher than its theoretically
expected value in 3D systems.Comment: Text revised version. 4 eps figs unchange
Comparison of Sheep and Goats to the Acute Toxic Effects of Foothill Death Camas
Death camas (Zigadenus spp) is a perennial forb found throughout the western United States, which is known to kill both sheep and cattle. In a previous study, goats appeared to be somewhat resistant to the adverse effects of death camas. Therefore, the objective of this study was to directly compare the susceptibility of goats and sheep to the acute toxic effects of death camas. Sheep and goats were dosed at 0.5, 1.0, 2.0, 4.0, and 6.0 g death camas per kg BW. The data presented in this manuscript suggest that goats are more susceptible to death camas than sheep. There were no differences in the serum concentrations of zygadenine in sheep versus goats. There was a difference between goats and sheep in the severity of observed clinical signs of poisoning. This is highlighted by the fact that five goats from the two highest doses died, whereas none of the sheep died. Consequently, when grazing goats in death camas infested pastures as much caution, if not more, should be taken than one would with sheep. Additionally, the data presented in the study suggests that goats can be used as a small ruminant model to study the toxic effects of death camas
A case of acute myeloid leukemia with promyelocytic features characterized by expression of a novel RARG-CPSF6 fusion
Key Points
Novel RARG-CPSF6 fusion in an AML case with promyelocytic features and no evidence of PML-RARA or X-RARA fusion. Gene fusions involving RARG can initiate AML with promyelocytic morphological features.</jats:p
RR Lyrae stars in four globular clusters in the Fornax dwarf galaxy
(Abridged) We have surveyed four globular clusters in the Fornax dwarf galaxy
for RR Lyrae stars, using archival HST observations. We identify 197 new RR
Lyrae stars in these four clusters. Despite the short observational baseline,
we derive periods, light-curves, and photometric parameters for each. The
Fornax clusters have exceptionally large RR Lyrae specific frequencies compared
with the Galactic globular clusters. Furthermore, the Fornax cluster RR Lyrae
stars are unusual in that their characteristics are intermediate between the
two Galactic Oosterhoff groups. In this respect the Fornax clusters are similar
to the field populations in several dwarf galaxies. We revise previous
measurements of the HB morphology in each cluster. The Fornax clusters closely
resemble the ``young'' Galactic halo population defined by Zinn. The existence
of the second parameter effect among the Fornax clusters is also confirmed.
Finally, we determine foreground reddening and distance estimates for each
cluster. We find a mean distance modulus to Fornax of (m-M)_0 = 20.66 +/- 0.03
(random) +/- 0.15 (systematic). Our measurements are consistent with a line of
sight depth of 8-10 kpc for this galaxy, matching its projected dimensions, and
incompatible with tidal model explanations for the observed high velocity
dispersions in many dSph galaxies. Dark matter dominance is suggested.Comment: 26 pages, 6 figures. Accepted for publication in MNRAS. Table 2 and
Figure 2 will only be available in the electronic version. On-line data will
soon be available at http://www.ast.cam.ac.uk/STELLARPOPS/Fornax_RRlyr
Neurobehavioral Evaluation of Mice Dosed With Water Hemlock Green Seeds and Tubers
Water hemlock are plants of the genus Cicuta and are toxic to animals and humans. The primary toxin is cicutoxin, which is abundant in the tubers, but less abundant in other parts of the plant. Other cicutoxin-like compounds, such as cicutols, which may also contribute to the toxicity of water hemlock, are more abundant in non-tuber plant parts. The objective of this study was to determine the toxicity of different parts of water hemlock and characterize their effects on motor function/coordination in mice. An aqueous extract of green seeds, dry seeds, tubers, flowers and stems of water hemlock was dosed orally to mice to determine their acute toxicity. The results indicated that only the green seeds and tubers were sufficiently toxic to animals to induce seizures and death. The LD50 for tubers and green seeds was 17 mg/kg and 1320 mg/kg, respectively. Several tests were used to evaluate motor function and behavior in treated mice including rotarod, tremor monitor, and open field. The animals were evaluated before dosing and 30, 90, 120, 150, 180, 240, and 300 min after dosing. Water hemlock affected muscle function of mice, including their balance and motility on a rotarod, motor activity, and exploratory and anxiety-related (i.e., thigmotaxis) behaviors in an open field. Seizures interspersed with central nervous system (CNS) motor depression were observed in animals poisoned by water hemlock. Extracts from tubers were especially potent in causing a decrease in motor activity and resultant depression, while periodically provoking seizures. Further research is needed to identify, quantitate, and purify cicutoxin and the other polyacetylene compounds from the various water hemlock plant parts to evaluate their toxicity and effects on motor function
The young stellar population at the center of NGC 205
Context. NGC 205 is a peculiar dwarf elliptical galaxy hosting in its center
a population of young blue stars. Their origin is still matter of debate, the
central fresh star formation activity possibly being related to dynamical
interactions between NGC 205 and M31. Aims. The star formation history in the
central 30\arcsec (120 pc) around the NGC 205 central nucleus is
investigated in order to obtain clues to the origin of the young stellar
population. Methods. Deep HST/ACS CCD photometry is compared with theoretical
isochrones and luminosity functions to characterize the stellar content of the
region under study and compute the recent SF rate. Results. Our photometry
reveals a previously undetected blue plume of young stars clearly
distinguishable down to I26. Our analysis suggests that 1.9
M were produced between approximately 62 Myr and 335 Myr ago in the NGC
205 inner regions, with a latest minor episode occurring 25 Myr ago. This
implies a star formation rate of M/yr over this
period. Conclusions. The excellent fit of the observed luminosity function of
young main sequence stars obtained with a model having a constant star
formation rate argues against a tidally triggered star formation activity over
the last 300 Myr. Rather, a constant SF may be consistent with NGC 205
being on its first interaction with M 31.Comment: 5 pages, 2 figures, accepted for publication in A&A letter
Full Spectrum Archaeology
Full Spectrum Archaeology (FSA) is an aspiration stemming from the convergence of archaeology’s fundamental principles with international heritage policies and community preferences. FSA encompasses study and stewardship of the full range of heritage resources in accord with the full range of associated values and through the application of treatments selected from the full range of appropriate options. Late modern states, including British Columbia, Canada, nominally embrace de jure heritage policies consonant with international standards yet also resist de facto heritage management practice grounded in professional ethics and local values and preferences. In response, inheritor communities and their allies in archaeology are demonstrating the benefits of FSA and reclaiming control over cultural heritage. Archaeology and heritage management driven by altruistic articulation of communal, educational, scientific and other values further expose shortcomings and vulnerabilities of late modern states as well as public goods in and from FSA
Inference on periodicity of circadian time series
Estimation of the period length of time-course data from cyclical biological processes, such as those driven by the circadian pacemaker, is crucial for inferring the properties of the biological clock found in many living organisms. We propose a methodology for period estimation based on spectrum resampling (SR) techniques. Simulation studies show that SR is superior and more robust to non-sinusoidal and noisy cycles than a currently used routine based on Fourier approximations. In addition, a simple fit to the oscillations using linear least squares is available, together with a non-parametric test for detecting changes in period length which allows for period estimates with different variances, as frequently encountered in practice. The proposed methods are motivated by and applied to various data examples from chronobiology
Can adverse maternal and perinatal outcomes be predicted when blood pressure becomes elevated? Secondary analyses from the CHIPS (Control of Hypertension In Pregnancy Study) randomized controlled trial.
INTRODUCTION: For women with chronic or gestational hypertension in CHIPS (Control of Hypertension In Pregnancy Study, NCT01192412), we aimed to examine whether clinical predictors collected at randomization could predict adverse outcomes. MATERIAL AND METHODS: This was a planned, secondary analysis of data from the 987 women in the CHIPS Trial. Logistic regression was used to examine the impact of 19 candidate predictors on the probability of adverse perinatal (pregnancy loss or high level neonatal care for >48 h, or birthweight <10th percentile) or maternal outcomes (severe hypertension, preeclampsia, or delivery at <34 or <37 weeks). A model containing all candidate predictors was used to start the stepwise regression process based on goodness of fit as measured by the Akaike information criterion. For face validity, these variables were forced into the model: treatment group ("less tight" or "tight" control), antihypertensive type at randomization, and blood pressure within 1 week before randomization. Continuous variables were represented continuously or dichotomized based on the smaller p-value in univariate analyses. An area-under-the-receiver-operating-curve (AUC ROC) of ≥0.70 was taken to reflect a potentially useful model. RESULTS: Point estimates for AUC ROC were <0.70 for all but severe hypertension (0.70, 95% CI 0.67-0.74) and delivery at <34 weeks (0.71, 95% CI 0.66-0.75). Therefore, no model warranted further assessment of performance. CONCLUSIONS: CHIPS data suggest that when women with chronic hypertension develop an elevated blood pressure in pregnancy, or formerly normotensive women develop new gestational hypertension, maternal and current pregnancy clinical characteristics cannot predict adverse outcomes in the index pregnancy
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