2,744 research outputs found
A Modular Tray Growth System for Barley
Determining when a barley plant starts and finishes meiosis is not trivial as when the spikelets undergo meiosis, the spike is not visible as it is still well within the leaf sheath on the developing tiller. This is a general constraint for any experiment involving meiosis, such as cytology, RNA extractions, or abiotic stress treatments aiming to target such a developmental stage. The lack of synchronicity between barley tillers within the same plant exacerbates the difficulty to determine the overall meiotic stage of a plant at a certain time.Given the lack of a nondestructive staging system for predicting the entry into meiosis and the problems of working with large pot plant systems, a modular plant growing is proposed. This system enables the growth of a high number of plants in a small surface, each producing a single tiller. The modular tray system was used to generate a nondestructive prediction tool for meiosis by using external morphological features. As an example, the system is used here for heat treating F1 plants in early meiosis stages to modify recombination.</p
Bio-Inspired Multi-Layer Spiking Neural Network Extracts Discriminative Features from Speech Signals
Spiking neural networks (SNNs) enable power-efficient implementations due to
their sparse, spike-based coding scheme. This paper develops a bio-inspired SNN
that uses unsupervised learning to extract discriminative features from speech
signals, which can subsequently be used in a classifier. The architecture
consists of a spiking convolutional/pooling layer followed by a fully connected
spiking layer for feature discovery. The convolutional layer of leaky,
integrate-and-fire (LIF) neurons represents primary acoustic features. The
fully connected layer is equipped with a probabilistic spike-timing-dependent
plasticity learning rule. This layer represents the discriminative features
through probabilistic, LIF neurons. To assess the discriminative power of the
learned features, they are used in a hidden Markov model (HMM) for spoken digit
recognition. The experimental results show performance above 96% that compares
favorably with popular statistical feature extraction methods. Our results
provide a novel demonstration of unsupervised feature acquisition in an SNN
Evaluation of Phage Display Discovered Peptides as Ligands for Prostate-Specific Membrane Antigen (PSMA)
The aim of this study was to identify potential ligands of PSMA suitable for further development as novel PSMA-targeted peptides using phage display technology. The human PSMA protein was immobilized as a target followed by incubation with a 15-mer phage display random peptide library. After one round of prescreening and two rounds of screening, high-stringency screening at the third round of panning was performed to identify the highest affinity binders. Phages which had a specific binding activity to PSMA in human prostate cancer cells were isolated and the DNA corresponding to the 15-mers were sequenced to provide three consensus sequences: GDHSPFT, SHFSVGS and EVPRLSLLAVFL as well as other sequences that did not display consensus. Two of the peptide sequences deduced from DNA sequencing of binding phages, SHSFSVGSGDHSPFT and GRFLTGGTGRLLRIS were labeled with 5-carboxyfluorescein and shown to bind and co-internalize with PSMA on human prostate cancer cells by fluorescence microscopy. The high stringency requirements yielded peptides with affinities KD∼1 μM or greater which are suitable starting points for affinity maturation. While these values were less than anticipated, the high stringency did yield peptide sequences that apparently bound to different surfaces on PSMA. These peptide sequences could be the basis for further development of peptides for prostate cancer tumor imaging and therapy. © 2013 Shen et al
Probing elastic and inelastic breakup contributions to intermediate-energy two-proton removal reactions
The two-proton removal reaction from 28Mg projectiles has been studied at 93
MeV/u at the NSCL. First coincidence measurements of the heavy 26Ne projectile
residues, the removed protons and other light charged particles enabled the
relative cross sections from each of the three possible elastic and inelastic
proton removal mechanisms to be determined. These more final-state-exclusive
measurements are key for further interrogation of these reaction mechanisms and
use of the reaction channel for quantitative spectroscopy of very neutron-rich
nuclei. The relative and absolute yields of the three contributing mechanisms
are compared to reaction model expectations - based on the use of eikonal
dynamics and sd-shell-model structure amplitudes.Comment: Accepted for publication in Physical Review C (Rapid Communication
Elastic breakup cross sections of well-bound nucleons
The 9Be(28Mg,27Na) one-proton removal reaction with a large proton separation
energy of Sp(28Mg)=16.79 MeV is studied at intermediate beam energy.
Coincidences of the bound 27Na residues with protons and other light charged
particles are measured. These data are analyzed to determine the percentage
contributions to the proton removal cross section from the elastic and
inelastic nucleon removal mechanisms. These deduced contributions are compared
with the eikonal reaction model predictions and with the previously measured
data for reactions involving the re- moval of more weakly-bound protons from
lighter nuclei. The role of transitions of the proton between different bound
single-particle configurations upon the elastic breakup cross section is also
quantified in this well-bound case. The measured and calculated elastic breakup
fractions are found to be in good agreement.Comment: Phys. Rev. C 2014 (accepted
Ribose 2′-O-methylation provides a molecular signature for the distinction of self and non-self mRNA dependent on the RNA sensor Mda5
The 5'-cap-structures of higher eukaryote mRNAs are ribose 2'-O-methylated. Likewise, a number of viruses replicating in the cytoplasm of eukayotes have evolved 2'-O-methyltransferases to modify autonomously their mRNAs. However, a defined biological role of mRNA 2'-O-methylation remains elusive. Here we show that viral mRNA 2'-O-methylation is critically involved in subversion of type-I-interferon (IFN-I) induction. We demonstrate that human and murine coronavirus 2'-O-methyltransferase mutants induce increased IFN-I expression, and are highly IFN-I sensitive. Importantly, IFN-I induction by 2'-O-methyltransferase-deficient viruses is dependent on the cytoplasmic RNA sensor melanoma differentiation-associated gene 5 (MDA5). This link between MDA5-mediated sensing of viral RNA and mRNA 2'-O-methylation suggests that RNA modifications, such as 2'-O-methylation, provide a molecular signature for the discrimination of self and non-self mRNA
Correlation Functions of Large N Chern-Simons-Matter Theories and Bosonization in Three Dimensions
We consider the conformal field theory of N complex massless scalars in 2+1
dimensions, coupled to a U(N) Chern-Simons theory at level k. This theory has a
't Hooft large N limit, keeping fixed \lambda = N/k. We compute some
correlation functions in this theory exactly as a function of \lambda, in the
large N (planar) limit. We show that the results match with the general
predictions of Maldacena and Zhiboedov for the correlators of theories that
have high-spin symmetries in the large N limit. It has been suggested in the
past that this theory is dual (in the large N limit) to the Legendre transform
of the theory of fermions coupled to a Chern-Simons gauge field, and our
results allow us to find the precise mapping between the two theories. We find
that in the large N limit the theory of N scalars coupled to a U(N)_k
Chern-Simons theory is equivalent to the Legendre transform of the theory of k
fermions coupled to a U(k)_N Chern-Simons theory, thus providing a bosonization
of the latter theory. We conjecture that perhaps this duality is valid also for
finite values of N and k, where on the fermionic side we should now have (for
N_f flavors) a U(k)_{N-N_f/2} theory. Similar results hold for real scalars
(fermions) coupled to the O(N)_k Chern-Simons theory.Comment: 49 pages, 16 figures. v2: added reference
Stringy Stability of Charged Dilaton Black Holes with Flat Event Horizon
Electrically charged black holes with flat event horizon in anti-de Sitter
space have received much attention due to various applications in Anti-de
Sitter/Conformal Field Theory (AdS/CFT) correspondence, from modeling the
behavior of quark-gluon plasma to superconductor. Crucial to the physics on the
dual field theory is the fact that when embedded in string theory, black holes
in the bulk may become vulnerable to instability caused by brane
pair-production. Since dilaton arises naturally in the context of string
theory, we study the effect of coupling dilaton to Maxwell field on the
stability of flat charged AdS black holes. In particular, we study the
stability of Gao-Zhang black holes, which are locally asymptotically anti-de
Sitter. We find that for dilaton coupling parameter > 1, flat black
holes are stable against brane pair production, however for 0 < < 1,
the black holes eventually become unstable as the amount of electrical charges
is increased. Such instability however, behaves somewhat differently from that
of flat Reissner-Nordstr\"om black holes. In addition, we prove that the
Seiberg-Witten action of charged dilaton AdS black hole of Gao-Zhang type with
flat event horizon (at least in 5-dimension) is always logarithmically
divergent at infinity for finite values of , and is finite and positive
in the case tends to infinity . We also comment on the robustness of
our result for other charged dilaton black holes that are not of Gao-Zhang
type.Comment: Fixed some confusions regarding whether part of the discussions
concern electrically charged hole or magnetically charged one. No changes to
the result
Implementation of Integrated Learning Program in neurosciences during first year of traditional medical course: Perception of students and faculty
<p>Abstract</p> <p>Background</p> <p>Our college introduced an integrated learning program (ILP) for first year undergraduates with an aim to develop, implement and evaluate a module for CNS in basic sciences and to assess the feasibility of an ILP in phase I of medical education in a college following traditional medical curriculum.</p> <p>Methods</p> <p>The idea of implementing ILP for Central Nervous System (CNS) in phase one was conceived by curriculum development committee drawn from faculty of all phases. After a series of meetings of curriculum development committee, inputs from basic science and clinical departments, a time table was constructed. Various teaching learning methods, themes for integrated didactic lectures, case based learning and clinical exposure were decided. Basic science faculty were made to participate actively in both case based learning and hospital visits along with clinical experts. The completed program was evaluated based on structured questionnaire.</p> <p>Results</p> <p>Sixty percent students rated the program good to excellent with reference to appreciation, understanding and application of basic science knowledge in health and disease. Seventy eight percent felt that this program will help them perform better in later days of clinical training. However sixty percent students felt that ILP will not help them perform better at the first professional examination. Seventy two per cent of faculty agreed that this program improved understanding and application of basic science knowledge of students. Ninety percent of faculty felt that this program will help them perform better in later days of clinical training.</p> <p>Conclusion</p> <p>The adoption of present integrated module for CNS and the use of multiple teaching learning methods have been proven to be useful in acquisition of knowledge from the student satisfaction point of view. Students and faculty expressed an overall satisfaction towards ILP for CNS. The study showed that it is possible to adopt an integrated learning module in the first year of medical course under a conventional curriculum.</p
Genetic Variants Associated with Arsenic Susceptibility: Study of Purine Nucleoside Phosphorylase, Arsenic (+3) Methyltransferase, and Glutathione S-Transferase Omega Genes
BACKGROUND: Individual variability in arsenic metabolism may underlie individual susceptibility
toward arsenic-induced skin lesions and skin cancer. Metabolism of arsenic proceeds through
sequential reduction and oxidative methylation being mediated by the following genes: purine
nucleoside phosphorylase (PNP), arsenic (+3) methyltransferase (As3MT), glutathione S-transferase
omega 1 (GSTO1), and omega 2 (GSTO2). PNP functions as arsenate reductase; As3MT methylates
inorganic arsenic and its metabolites; and both GSTO1 and GSTO2 reduce the metabolites.
Alteration in functions of these gene products may lead to arsenic-specific disease manifestations.
OBJECTIVES: To find any probable association between arsenicism and the exonic single nucleotide
polymorphisms (SNPs) of the above-mentioned arsenic-metabolizing genes, we screened all the
exons in those genes in an arsenic-exposed population.
METHODS: Using polymerase chain reaction restriction fragment length polymorphism analysis, we
screened the exons in 25 cases (individuals with arsenic-induced skin lesions) and 25 controls (individuals
without arsenic-induced skin lesions), both groups drinking similar arsenic-contaminated
water. The exonic SNPs identified were further genotyped in a total of 428 genetically unrelated
individuals (229 cases and 199 controls) for association study.
RESULTS: Among four candidate genes, PNP, As3MT, GSTO1, and GSTO2, we found that distribution
of three exonic polymorphisms, His20His, Gly51Ser, and Pro57Pro of PNP, was associated
with arsenicism. Genotypes having the minor alleles were significantly overrepresented in the case
group: odds ratio (OR) = 1.69 [95% confidence interval (CI), 1.08–2.66] for His20His; OR = 1.66
[95% CI, 1.04–2.64] for Gly51Ser; and OR = 1.67 [95% CI, 1.05–2.66] for Pro57Pro.
CONCLUSIONS: The results indicate that the three PNP variants render individuals susceptible
toward developing arsenic-induced skin lesions.
KEY WORDS: arsenic, As3MT, GSTO1, GSTO2, PNP, skin lesion, susceptibility. Environ Health
Perspect 116:501–505 (2008). doi:10.1289/ehp.10581 available via http://dx.doi.org/ [Online
14 January 2008
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