Maximizing the amplitude of coherent phonons with shaped laser pulses

We perform model calculations of coherent lattice vibrations in solids driven by ultrashort laser pulses. In order to maximize the amplitude of the coherent phonon in the time domain, an evolutionary algorithm optimizes the driving laser field. We find that only a Fourier-limited single pulse yields the maximum phonon amplitude, irrespective of the actual physical excitation mechanism (impulsive or displacive). This result is in clear contrast to the widespread intuition that excitation by a pulse train in phase with the oscillation leads to the largest amplitude of an oscillator. We rationalize this result by an intuitive model and discuss implications for other nonlinear processes such as optical rectification

Performance of Mixture-Ratio-Controlled Hybrid Rockets for Nominal Fuel Regression

This paper discusses the impacts of oxidizer-to-fuel mass ratio (O/F) shifts on the flight performance of single-stage sounding rockets using the flight simulations of three scales of O/F-controlled and O/F-uncontrolled hybrid rockets under a nominal fuel regression behavior without uncertainty. The flight simulation code includes three factors dependent on the O/F: thermodynamic states of the burned gas (theoretical Isp), shifts in c∗ efficiency, and nozzle throat erosion. In the flight simulations, a thrust control law was applied to increase the apogee and evaluate the effects of O/F shifts in the thrust curve including throttling. For the best cases in each scale, O/F-controlled hybrid rockets slightly improved the performance by 2.03–2.42% in the averaged specific impulse. However, the performance of the O/F-controlled sounding rockets is essentially the same as the O/F-uncontrolled type under the median regression behavior: especially when considering the slight increases in the mass and complexity of the oxidizer feed system needed for O/F control. Considerable scale effects on the throat erosion and theoretical Isp were observed, but that of the c∗ efficiency was negligible. The improvement of the theoretical Isp was the primary contributor to flight performance, which was responsible for a larger than 70% share in the total Isp increase. The second largest contribution was the improvement of the c∗ efficiency with a share of 21.8–24.3%. The O/F control gave an improvement of throat erosion corresponding to 5.75% in the total Isp increase for the smallest scale; but, with increasing of the scale, the throat area increase ratio became small so that the throat erosion improvement contribution was reduced to 1.21%

Performance of Mixture-Ratio-Controlled Hybrid Rockets under Uncertainties in Fuel Regression

This paper evaluates various sources of oxidizer to fuel mass ratio (O/F) shifts in hybrid rockets and paths (physical phenomena) through which these O/F shifts affect flight performance. Moreover, the performance increase of O/F control in hybrid rockets is evaluated. Vertical launches of O/F uncontrolled and O/F controlled of hybrid sounding rockets were simulated under two uncertainty models of fuel regression behavior based on experimental data: a) systematic errors with a constant deviation within ±3σ±3σ and 2) random errors subject to a probability distribution. These simulations included all sources of O/F shifts that originated in the fuel regression behavior and all paths through which the O/F shifts affect flight performance. Residual propellant mass and decreases in specific impulse are found to be the dominant causes of performance loss under both uncertainty models. For both cases 1 and 2, the O/F-controlled hybrid rockets maintained the performance expected under nominal fuel regression behavior, whereas the O/F-uncontrolled hybrid rockets had a lower performance by upwards of 6.69 and 4.06% in ΔVΔV for cases 1 and 2, respectively. For case 2, 3008 flight simulations revealed that the worst case of the O/F-controlled hybrid rocket had a 4.06 to 4.49% larger ΔVΔV and 10.5 to 13.3% higher apogee than that of the O/F-uncontrolled hybrid rocket, and that the O/F-uncontrolled hybrid rocket had a 6.61 times larger standard deviation in ΔVΔV. These results mean that the elimination O/F shift in hybrid rockets significantly improves performance, as well as the accuracy and reliability of performance predictions

Indication of Te segregation in laser-irradiated ZnTe observed by in situ coherent-phonon spectroscopy

We irradiate a ZnTe single crystal with 10-fs laser pulses at a repetition rate of 80 MHz and investigate its resulting gradual modification by means of coherent-phonon spectroscopy. We observe the emergence of a phonon mode at about 3.6 THz whose amplitude and lifetime grow monotonously with irradiation time. The speed of this process depends sensitively on the pump-pulse duration. Our observations strongly indicate that the emerging phonon mode arises from a Te phase induced by multiphoton absorption of incident laser pulses. A potential application of our findings is laser-machining of microstructures in the bulk of a ZnTe crystal, a highly relevant electrooptic material

WildSilkbase: An EST database of wild silkmoths

<p>Abstract</p> <p>Background</p> <p>Functional genomics has particular promise in silkworm biology for identifying genes involved in a variety of biological functions that include: synthesis and secretion of silk, sex determination pathways, insect-pathogen interactions, chorionogenesis, molecular clocks. Wild silkmoths have hardly been the subject of detailed scientific investigations, owing largely to non-availability of molecular and genetic data on these species. As a first step, in the present study we generated large scale expressed sequence tags (EST) in three economically important species of wild silkmoths. In order to make these resources available for the use of global scientific community, an EST database called 'WildSilkbase' was developed.</p> <p>Description</p> <p>WildSilkbase is a catalogue of ESTs generated from several tissues at different developmental stages of 3 economically important saturniid silkmoths, an Indian golden silkmoth, <it>Antheraea assama</it>, an Indian tropical tasar silkmoth, <it>A. mylitta </it>and eri silkmoth, <it>Samia cynthia ricini</it>. Currently the database is provided with 57,113 ESTs which are clustered and assembled into 4,019 contigs and 10,019 singletons. Data can be browsed and downloaded using a standard web browser. Users can search the database either by BLAST query, keywords or Gene Ontology query. There are options to carry out searches for species, tissue and developmental stage specific ESTs in BLAST page. Other features of the WildSilkbase include cSNP discovery, GO viewer, homologue finder, SSR finder and links to all other related databases. The WildSilkbase is freely available from <url>http://www.cdfd.org.in/wildsilkbase/</url>.</p> <p>Conclusion</p> <p>A total of 14,038 putative unigenes was identified in 3 species of wild silkmoths. These genes provide important resources to gain insight into the functional and evolutionary study of wild silkmoths. We believe that WildSilkbase will be extremely useful for all those researchers working in the areas of comparative genomics, functional genomics and molecular evolution in general, and gene discovery, gene organization, transposable elements and genome variability of insect species in particular.</p

The efficacy of cefmetazole against pyelonephritis caused by extended-spectrum beta-lactamase-producing Enterobacteriaceae

SummaryObjectivesUrinary tract infections (UTIs) caused by extended-spectrum beta-lactamase (ESBL)-producing Enterobacteriaceae are on the increase. Although cefmetazole is stable in vitro against the hydrolyzing activity of ESBLs, no clinical study has ever evaluated its role in infections caused by these organisms. We therefore evaluated the efficacy of cefmetazole compared to carbapenems against pyelonephritis caused by ESBL-producing Enterobacteriaceae.MethodsA retrospective chart review was conducted at a tertiary care hospital from August 2008 to July 2010. Chart reviews were done for patients with ESBL-producing organisms in urine identified in the microbiology database. Patients who were treated with cefmetazole were compared to those treated with carbapenems. The clinical and bacteriological cure rates at 4 weeks after completion of therapy were evaluated.ResultsTwo hundred and fifty-six urine cultures growing ESBL-producing organisms were identified during the study period. Ten patients treated with cefmetazole and 12 patients treated with carbapenems were evaluated. There was no difference in clinical (9/10 vs. 12/12, p=0.46) or bacteriological cure rate (5/7 vs. 6/7, p=1.00) at 4 weeks after the completion of therapy. There was no difference in the incidence of adverse effects (2/10 vs. 2/12, p=1.00).ConclusionsCefmetazole may be a useful option for the treatment of UTIs caused by ESBL-producing organisms. Prospective and larger sized studies are needed to confirm our findings

A spectral-based high dynamic range image data format by combination of cosine and wavelet basis functions

画像電子学会第243回研究会 発表スライド ; 開催場所 : 鹿児島大学, 鹿児島市 ; 開催日 : 2009年3月5-6日画像電子学会 第243回研究会講演予稿, 08-05-26, pp.147-153に記載

Model figging of articulated objects

本稿では人体や手などに代表される多関節物体の三次元姿勢を画像から推定するモデルフィッティングの技術についてサーベイする。画像によるモデルフィッティングの枠組みを,1)推定に利用される画像特徴,2)画像と照合するモデルの表現と照合のパラメータ空間,3)照合時の評価関数と最適解の探索手法,にわけて多関節物体の三次元姿勢推定に特徴的な要素を上記三つの観点から比較整理することを試みる。In this paper, we present a survey report for the model fitting method to estimate3-D posture of articulated objects such as human body and hand. We decompose the model fitting framework into the following threee lements: 1)image feature, 2)model description and parameter space for model-image matching and 3)matching function and its optimization. From the viewpoint of these three issues, we try to compare the various methods of model fitting to each other and summarize them

Altered expression of testis-specific genes, piRNAs, and transposons in the silkworm ovary masculinized by a W chromosome mutation

<p>Abstract</p> <p>Background</p> <p>In the silkworm, <it>Bombyx mori</it>, femaleness is strongly controlled by the female-specific W chromosome. Originally, it was presumed that the W chromosome encodes female-determining gene(s), accordingly called <it>Fem</it>. However, to date, neither <it>Fem </it>nor any protein-coding gene has been identified from the W chromosome. Instead, the W chromosome is occupied with numerous transposon-related sequences. Interestingly, the silkworm W chromosome is a source of female-enriched PIWI-interacting RNAs (piRNAs). piRNAs are small RNAs of 23-30 nucleotides in length, which are required for controlling transposon activity in animal gonads. A recent study has identified a novel mutant silkworm line called KG, whose mutation in the W chromosome causes severe female masculinization. However, the molecular nature of KG line has not been well characterized yet.</p> <p>Results</p> <p>Here we molecularly characterize the KG line. Genomic PCR analyses using currently available W chromosome-specific PCR markers indicated that no large deletion existed in the KG W chromosome. Genetic analyses demonstrated that sib-crosses within the KG line suppressed masculinization. Masculinization reactivated when crossing KG females with wild type males. Importantly, the KG ovaries exhibited a significantly abnormal transcriptome. First, the KG ovaries misexpressed testis-specific genes. Second, a set of female-enriched piRNAs was downregulated in the KG ovaries. Third, several transposons were overexpressed in the KG ovaries.</p> <p>Conclusions</p> <p>Collectively, the mutation in the KG W chromosome causes broadly altered expression of testis-specific genes, piRNAs, and transposons. To our knowledge, this is the first study that describes a W chromosome mutant with such an intriguing phenotype.</p