1,260 research outputs found
Effect of Soil Buffer Capacity on Soil Reaction (pH) Modification and Subsequent Effects on Growth and Nutrient Uptake of Plantanus occidentalis L. Seedlings
The buffer capacity of a soil is a significant factor in determining the longevity of soil reaction (pH) adjustments by aluminum sulfate, Al2(SO4)3, or calcium carbonate, CaCOâ‚‚. After 12 weeks the modified pH values of the highly buffered Emory silt loam had changed substantially toward the original pH value of 7.6. Modified pH values for the Groseclose silt loam soil remained essentially unchanged under the same conditions. These differences in soil response to modified soil pH are related to the differences in the percentage of vermiculite chlorite and chlorite in the clay fractions of the two soils. The longevity of soil pH modification is related to total sycamore seedling dry weight and nutrient uptake. Though these components were significantly affected for plants grown in a Groseclose soil, the lack of significant response differences, except at the extremely low pH adjustment (5.21), in the Emory soil suggests a rapid change in modified soil pH toward the original soil pH value. The condition of the seedlings coupled with total dry weight accumulation and foliar nutrient content elimiates acid toxicity as a factor affecting growth and nutrient uptake. Plants grown in the Groseclose soil at pH 4.31 could be the exception
Effect of Soil Buffer Capacity on Soil Reaction (pH) Modification and Subsequent Effects on Growth and Nutrient Uptake of Plantanus occidentalis L. Seedlings
The buffer capacity of a soil is a significant factor in determining the longevity of soil reaction (pH) adjustments by aluminum sulfate, Al2(SO4)3, or calcium carbonate, CaCOâ‚‚. After 12 weeks the modified pH values of the highly buffered Emory silt loam had changed substantially toward the original pH value of 7.6. Modified pH values for the Groseclose silt loam soil remained essentially unchanged under the same conditions. These differences in soil response to modified soil pH are related to the differences in the percentage of vermiculite chlorite and chlorite in the clay fractions of the two soils. The longevity of soil pH modification is related to total sycamore seedling dry weight and nutrient uptake. Though these components were significantly affected for plants grown in a Groseclose soil, the lack of significant response differences, except at the extremely low pH adjustment (5.21), in the Emory soil suggests a rapid change in modified soil pH toward the original soil pH value. The condition of the seedlings coupled with total dry weight accumulation and foliar nutrient content elimiates acid toxicity as a factor affecting growth and nutrient uptake. Plants grown in the Groseclose soil at pH 4.31 could be the exception
Resistance to chemotherapy in advanced ovarian cancer: mechanisms and current strategies
Although treatment for advanced epithelial ovarian cancer has improved over recent years with the introduction of taxane–platinum chemotherapy, the majority of patients will relapse, and in most the disease remains incurable. A thorough understanding of drug resistance mechanisms is needed, as this remains the largest obstacle in treating patients with recurrent disease. Multidrug resistance proteins, mismatch repair processes and alterations in the p53 pathway are examples of properties within tumour cells that may lead to drug resistance. Novel agents designed to circumvent these mechanisms (e.g. PSC 833, ONYX-015 and ADP53) are currently being investigated for ovarian cancer patients. Further improvements may result from the optimisation of existing first-line regimens with more creative schedules, perhaps involving sequential or intraperitoneal administration of existing drugs, and the incorporation of newer noncross-resistant drugs
Novae as a Mechanism for Producing Cavities around the Progenitors of SN 2002ic and Other SNe Ia
We propose that a nova shell ejected from a recurrent nova progenitor system
created the evacuated region around the explosion center of SN 2002ic. In this
picture, periodic shell ejections due to nova explosions on a white dwarf sweep
up the slow wind from the binary companion, creating density variations and
instabilities that lead to structure in the circumstellar medium (CSM). Our
model naturally explains the observed gap between the supernova explosion
center and the CSM in SN 2002ic, accounts for the density variations observed
in the CSM, and resolves the coincidence problem of the timing of the explosion
of SN 2002ic with respect to the apparent cessation of mass-loss in the
progenitor system. We also consider such nova outburst sweeping as a generic
feature of Type Ia supernovae with recurrent nova progenitors.Comment: Accepted to ApJL. 11 pages, 1 tabl
A Problematic Test of the Kin Selection Hypothesis Among the Urak-Lawoi of Ko Lipe, Thailand: Commentary on Camperio Ciani, Battaglia, and Liotta (2015)
Camperio Ciani et al. argued that the Urak-Lawoi people of Ko Lipe island live in a ‘‘traditional,’’ ‘‘subsistence primitive society’’ reminiscent of the ‘‘ancestral’’ human past and that their socio-cultural situation is ‘‘remarkably similar’’ to Samoa. On this basis, they asserted that the Ko Lipe Urak-Lawoi are an appropriate population for determining the role that kin selection played in the evolution of male androphilia. The purpose of this commentary is to outline some of our concerns with this characterization and with the statistical analyses conducted by Camperio Ciani et al. in their study of the Urak-Lawoi
A Problematic Test of the Kin Selection Hypothesis Among the Urak-Lawoi of Ko Lipe, Thailand: Commentary on Camperio Ciani, Battaglia, and Liotta (2015)
Camperio Ciani et al. argued that the Urak-Lawoi people of Ko Lipe island live in a ‘‘traditional,’’ ‘‘subsistence primitive society’’ reminiscent of the ‘‘ancestral’’ human past and that their socio-cultural situation is ‘‘remarkably similar’’ to Samoa. On this basis, they asserted that the Ko Lipe Urak-Lawoi are an appropriate population for determining the role that kin selection played in the evolution of male androphilia. The purpose of this commentary is to outline some of our concerns with this characterization and with the statistical analyses conducted by Camperio Ciani et al. in their study of the Urak-Lawoi
Type Ia Supernova Light Curve Inference: Hierarchical Bayesian Analysis in the Near Infrared
We present a comprehensive statistical analysis of the properties of Type Ia
SN light curves in the near infrared using recent data from PAIRITEL and the
literature. We construct a hierarchical Bayesian framework, incorporating
several uncertainties including photometric error, peculiar velocities, dust
extinction and intrinsic variations, for coherent statistical inference. SN Ia
light curve inferences are drawn from the global posterior probability of
parameters describing both individual supernovae and the population conditioned
on the entire SN Ia NIR dataset. The logical structure of the hierarchical
model is represented by a directed acyclic graph. Fully Bayesian analysis of
the model and data is enabled by an efficient MCMC algorithm exploiting the
conditional structure using Gibbs sampling. We apply this framework to the
JHK_s SN Ia light curve data. A new light curve model captures the observed
J-band light curve shape variations. The intrinsic variances in peak absolute
magnitudes are: sigma(M_J) = 0.17 +/- 0.03, sigma(M_H) = 0.11 +/- 0.03, and
sigma(M_Ks) = 0.19 +/- 0.04. We describe the first quantitative evidence for
correlations between the NIR absolute magnitudes and J-band light curve shapes,
and demonstrate their utility for distance estimation. The average residual in
the Hubble diagram for the training set SN at cz > 2000 km/s is 0.10 mag. The
new application of bootstrap cross-validation to SN Ia light curve inference
tests the sensitivity of the model fit to the finite sample and estimates the
prediction error at 0.15 mag. These results demonstrate that SN Ia NIR light
curves are as effective as optical light curves, and, because they are less
vulnerable to dust absorption, they have great potential as precise and
accurate cosmological distance indicators.Comment: 24 pages, 15 figures, 4 tables. Accepted for publication in ApJ.
Corrected typo, added references, minor edit
Status of the 80Mbit/s Receiver for the CMS digital optical link
The first prototype of the 80Mbit/s optical receiver ASIC for the CMS digital optical link has been manufactured in a 0.25µm commercial CMOS process. The circuit design has been made using radiation tolerant layout techniques. Its performance satisfies the low power, wide dynamic range, sensitivity and speed specifications. The radiation hardness of the receiver has been verified irradiating the diode with 6 MeV neutrons (up to 6.5·1014 n/cm2) and the receiver circuit with 10KeV X-rays (up to 20 Mrad). A second prototype has been submitted for fabrication in the same commercial CMOS process. I
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