2,911 research outputs found
Cadmium and arsenic-induced-stress differentially modulates Arabidopsis root architecture, peroxisome distribution, enzymatic activities and their nitric oxide content
In plant cells, cadmium (Cd) and arsenic (As) exert toxicity mainly by inducing oxidative stress through an imbalance between the production of reactive oxygen species (ROS) and reactive nitrogen species (RNS), and their detoxification. Nitric oxide (NO) is a RNS acting as signalling molecule coordinating plant development and stress responses, but also as oxidative stress inducer, depending on its cellular concentration. Peroxisomes are versatile organelles involved in plant metabolism and signalling, with a role in cellular redox balance thanks to their antioxidant enzymes, and their RNS (mainly NO) and ROS. This study analysed Cd or As effects on peroxisomes, and NO production and distribution in the root system, including primary root (PR) and lateral roots (LRs). Arabidopsis thaliana wild-type and transgenic plants enabling peroxisomes to be visualized in vivo, through the expression of the 35S-cyan fluorescent protein fused to the peroxisomal targeting signal1 (PTS1) were used. Peroxisomal enzymatic activities including the antioxidant catalase, the H2O2-generating glycolate oxidase, and the hydroxypyruvate reductase, and root system morphology were also evaluated under Cd/As exposure. Results showed that Cd and As differently modulate these activities, however, catalase activity was inhibited by both. Moreover, Arabidopsis root system was altered, with the pollutants differently affecting PR growth, but similarly enhancing LR formation. Only in the PR apex, and not in LR one, Cd more than As caused significant changes in peroxisome distribution, size, and in peroxisomal NO content. By contrast, neither pollutant caused significant changes in peroxisomes size and peroxisomal NO content in the LR apex
Through the lens of sequence submodularity
Several real-world problems in engineering and applied science require the selection of sequences that maximize a given reward function. Optimizing over sequences as opposed to sets requires exploring an exponentially larger search space and can become prohibitive in most cases of practical interest. However, if the objective function is submodular (intuitively, it exhibits a diminishing return property), the optimization problem becomes more manageable. Recently, there has been increasing interest in sequence submodularity in connection with applications such as recommender systems and online ad allocation. However, mostly ad hoc models and solutions have emerged within these applicative contexts. In consequence, the field appears fragmented and lacks coherence. In this paper, we offer a unified view of sequence submodularity and provide a generalized greedy algorithm that enjoys strong theoretical guarantees. We show how our approach naturally captures several application domains, and our algorithm encompasses existing methods, improving over them
A unifying look at sequence submodularity
Several real-world problems in engineering and applied science require the selection of sequences that maximize a given reward function. Optimizing over sequences as opposed to sets requires exploring an exponentially larger search space and can become prohibitive in most cases of practical interest. However, if the objective function is submodular (intuitively, it exhibits a diminishing return property), the optimization problem becomes more manageable. Recently, there has been increasing interest in sequence submodularity in connection with applications such as recommender systems and online ad allocation. However, mostly ad hoc models and solutions have emerged within these applicative contexts. In consequence, the field appears fragmented and lacks coherence. In this paper, we offer a unified view of sequence submodularity and provide a generalized greedy algorithm that enjoys strong theoretical guarantees. We show how our approach naturally captures several application domains, and our algorithm encompasses existing methods, improving over them. (C) 2021 The Authors. Published by Elsevier B.V
Urgent Need for Reduction in Greenhouse Gas Emissions in Industrial Processes: Are We Past the Tipping Point for Global Warming?
In a previous Guest Editorial (Piacentini and Mujumdar, 2007) and an article (Piacentini and Mujumdar, 2009), we analyzed the relation between climate change and industrial processes, mainly related to drying.Fil: Piacentini, Ruben Dario Narciso. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Rosario. Instituto de Física de Rosario (i); Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química, Física de los Materiales, Medioambiente y Energía; ArgentinaFil: Mujumdar, A. S. . Minerals, Metals & Materials Technology Centre ; Singapur. Institute of Chemical Technology; Indi
Positive Operator-Valued Measure reconstruction of a beam-splitter tree based photon-number-resolving detector
Here we present a reconstruction of the Positive Operator-Value Measurement
of a photon-number-resolving detector comprised of three 50:50 beamsplitters in
a tree configuration, terminated with four single-photon avalanche detectors.
The four detectors' outputs are processed by an electronic board that
discriminates detected photon number states from 0 to 4 and implements a "smart
counting" routine to compensate for dead time issues at high count rates
Predictors of HER2 gene amplification in immunohistochemistry score 2+ Early Breast Cancer according to 2018 ASCO/CAP guidelines: a single institution analysis.
Background: HER2 overexpression occurs in approximately
15-20% of invasive breast cancers (BC). From a
pathological point of view HER2 positivity is defined by
intense circumferential membrane complete staining in
more than 10% of tumour cells in immunohistochemistry
(IHC score 3+). When complete circumferential staining
is weak to moderate (IHC score 2+) double probe in situ
ibridation (ISH) is mandatory to define HER2 status. In
2018 ASCO/CAP guidelines were updated to provide
additional guidance in HER2 equivocal cases to allow a
greater discrimination between positive and negative
cases. Our aim is to find predictors of HER2 positivity
among IHC score 2+ early breast cancer specimens analysed
according to 2018 ASCO/CAP guidelines.
Patients and methods: 253 cases of early BC diagnosed
at Modena Cancer Center between November 2013 and
August 2017 were identified. Stage, ISH result, hormonal
receptor status (HR), proliferation index (MIB1), and histological
grade were captured; menopausal status was available too. All IHC score 2+ cases were reclassified
according to 2018 ASCO/CAP guidelines. The association
between pathological tumour features, clinical characteristics
and ISH positivity was assessed using Fisher test.
Results: Overall, 25.7% IHC score 2+ BC resulted HER2
amplified in double probe ISH. High tumour grade (G3 vs
G1-2) and MIB1 > 20% significantly predict HER2 ISH
amplification (p=0,0001). No correlation was found according
to HR, stage, or menopausal status. The majority (185;
98.4%) of HER2-ve BC were reclassified as group 5 (HER2/
CEP17 ratio <2 and HER2 copy number <4 signals/cell)
except for 3 specimens classified as group 4 (HER2/CEP17
RATIO <2 and HER2 copy number \ub34 but <6 signals/cell).
In HER2+ve group the majority (62; 95.3%) specimens
were group 1 (HER2/CEP17 RATIO >2 and HER2 copy
number =4 signals/cell), no specimen was group 2, and only
3 cases were classified as group 3 (HER2/CEP17 RATIO
<2 and HER2 copy number >6 signals/cell).
Conclusions: In this IHC score 2+ BC series, reclassification
according to 2018 ASCO/CAP guidelines identified
only 4.6% group 3 and 1.6% group 4 cases. The routinely
assessment of grading and proliferation index could help
to predict HER2 amplification in IHC score 2+ samples
even if it must not substitute ISH assay in determining eligibility
for HER2 targeted therapies
Detailed study of the microwave emission of the supernova remnant 3C 396
We have observed the supernova remnant 3C~396 in the microwave region using
the Parkes 64-m telescope. Observations have been made at 8.4 GHz, 13.5 GHz,
and 18.6 GHz and in polarisation at 21.5 GHz. We have used data from several
other observatories, including previously unpublished observations performed by
the Green Bank Telescope at 31.2 GHz, to investigate the nature of the
microwave emission of 3C 396. Results show a spectral energy distribution
dominated by a single component power law emission with . Data do not favour the presence of anomalous microwave emission coming
from the source. Polarised emission at 21.5 GHz is consistent with
synchrotron-dominated emission. We present microwave maps and correlate them
with infrared (IR) maps in order to characterise the interplay between thermal
dust and microwave emission. IR vs. microwave TT plots reveal poor correlation
between mid-infrared and microwave emission from the core of the source. On the
other hand, a correlation is detected in the tail emission of the outer shell
of 3C 396, which could be ascribed to Galactic contamination.Comment: published in MNRA
Human pharmacogenomic variation of antihypertensive drugs: from population genetics to personalized medicine.
AIM: To investigate the human pharmacogenetic variation related to antihypertensive drugs, providing a survey of functional interpopulation differences in hypertension pharmacogenes.
MATERIALS & METHODS: The study was divided into two stages. In the first stage, we analyzed 1249 variants located in 57 hypertension pharmacogenes. This first-stage analysis confirmed that geographic origin strongly affects hypertension pharmacogenomic variation and that 31 pharmacogenes are geographically differentiated. In the second stage, we focused our attention on the ethnic-differentiated pharmacogenes, investigating 55,521 genetic variants. In silico analyses were performed to predict the effect of genetic variation.
RESULTS: Our analyses indicated functional interpopulation differences, suggesting insight into the mechanisms of antihypertensive drug response. Moreover, our data suggested that rare variants mainly determine the functionality of genes related to antihypertensive drugs.
CONCLUSION: Our study provided important knowledge about the genetics of the antihypertensive drug response, suggesting that next-generation sequencing technologies may develop reliable pharmacogenetic tests for antihypertensive drugs
Quantum state reconstruction using binary data from on/off photodetection
The knowledge of the density matrix of a quantum state plays a fundamental
role in several fields ranging from quantum information processing to
experiments on foundations of quantum mechanics and quantum optics. Recently, a
method has been suggested and implemented in order to obtain the reconstruction
of the diagonal elements of the density matrix exploiting the information
achievable with realistic on/off detectors, e.g. silicon avalanche
photo-diodes, only able to discriminate the presence or the absence of light.
The purpose of this paper is to provide an overview of the theoretical and
experimental developments of the on/off method, including its extension to the
reconstruction of the whole density matrix.Comment: revised version, 11 pages, 6 figures, to appear as a review paper on
Adv. Science Let
New radio observations of anomalous microwave emission in the HII region RCW175
We have observed the HII region RCW175 with the 64m Parkes telescope at
8.4GHz and 13.5GHz in total intensity, and at 21.5GHz in both total intensity
and polarization. High angular resolution, high sensitivity, and polarization
capability enable us to perform a detailed study of the different constituents
of the HII region. For the first time, we resolve three distinct regions at
microwave frequencies, two of which are part of the same annular diffuse
structure. Our observations enable us to confirm the presence of anomalous
microwave emission (AME) from RCW175. Fitting the integrated flux density
across the entire region with the currently available spinning dust models,
using physically motivated assumptions, indicates the presence of at least two
spinning dust components: a warm component with a relatively large hydrogen
number density n_H=26.3/cm^3 and a cold component with a hydrogen number
density of n_H=150/cm^3. The present study is an example highlighting the
potential of using high angular-resolution microwave data to break model
parameter degeneracies. Thanks to our spectral coverage and angular resolution,
we have been able to derive one of the first AME maps, at 13.5GHz, showing
clear evidence that the bulk of the AME arises in particular from one of the
source components, with some additional contribution from the diffuse
structure. A cross-correlation analysis with thermal dust emission has shown a
high degree of correlation with one of the regions within RCW175. In the center
of RCW175, we find an average polarized emission at 21.5GHz of
2.2\pm0.2(rand.)\pm0.3(sys.)% of the total emission, where we have included
both systematic and statistical uncertainties at 68% CL. This polarized
emission could be due to sub-dominant synchrotron emission from the region and
is thus consistent with very faint or non-polarized emission associated with
AME.Comment: Accepted for publication in the Astrophysical Journa
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