A tunable radiation source by coupling laser-plasma-generated electrons to a periodic structure

Near-infrared radiation around 1000 nm generated from the interaction of a high-density MeV electron beam, obtained by impinging an intense ultrashort laser pulse on a solid target, with a metal grating is observed experimentally. Theoretical modeling and particle-in-cell simulation suggest that the radiation is caused by the Smith-Purcell mechanism. The results here indicate that tunable terahertz radiation with tens GV=m field strength can be achieved by using appropriate grating parameter

Predicting death and readmission after intensive care discharge

Background: Despite initial recovery from critical illness, many patients deteriorate after discharge from the intensive care unit (ICU). We examined prospectively collected data in an attempt to identify patients at risk of readmission or death after intensive care discharge. Methods: This was a secondary analysis of clinical audit data from patients discharged alive from a mixed medical and surgical (non-cardiac) ICU. Results: Four hundred and seventy-five patients (11.2%) died in hospital after discharge from the ICU. Increasing age, time in hospital before intensive care admission, Acute Physiology and Chronic Health Evaluation II (APACHE II) score, and discharge Therapeutic Intervention Scoring System (TISS) score were independent risk factors for death after intensive care discharge. Three hundred and eighty-five patients (8.8%) were readmitted to intensive care during the same hospital admission. Increasing age, time in hospital before intensive care, APACHE II score, and discharge to a high dependency unit were independent risk factors for readmission. One hundred and forty-three patients (3.3%) were readmitted within 48 h of intensive care discharge. APACHE II scores and discharge to a high dependency or other ICU were independent risk factors for early readmission. The overall discriminant ability of our models was moderate with only marginal benefit over the APACHE II scores alone. Conclusions: We identified risk factors associated with death and readmission to intensive care. It was not possible to produce a definitive model based on these risk factors for predicting death or readmission in an individual patient.Not peer reviewedAuthor versio

Long-term microcarrier suspension cultures of human embryonic stem cells

AbstractThe conventional method of culturing human embryonic stem cells (hESC) is on two-dimensional (2D) surfaces, which is not amenable for scale up to therapeutic quantities in bioreactors. We have developed a facile and robust method for maintaining undifferentiated hESC in three-dimensional (3D) suspension cultures on matrigel-coated microcarriers achieving 2- to 4-fold higher cell densities than those in 2D colony cultures. Stable, continuous propagation of two hESC lines on microcarriers has been demonstrated in conditioned media for 6 months. Microcarrier cultures (MC) were also demonstrated in two serum-free defined media (StemPro and mTeSR1). MC achieved even higher cell concentrations in suspension spinner flasks, thus opening the prospect of propagation in controlled bioreactors

Preparation and ferroelectric properties of (124)-oriented SrBi4Ti4O15 ferroelectric thin film on (110)-oriented LaNiO3 electrode

A (124)-oriented SrBi4Ti4O15 (SBTi) ferroelectric thin film with high volume fraction of {\alpha}SBTi(124)=97% was obtained using a metal organic decomposition process on SiO2/Si substrate coated by (110)-oriented LaNiO3 (LNO) thin film. The remanent polarization and coercive field for (124)-oriented SBTi film are 12.1 {\mu}C/cm2 and 74 kV/cm, respectively. No evident fatigue of (124)-oriented SBTi thin film can be observed after 1{\times}10e9 switching cycles. Besides, the (124)-oriented SBTi film can be uniformly polarized over large areas using a piezoelectric-mode atomic force microscope. Considering that the annealing temperature was 650{\deg}C and the thickness of each deposited layer was merely 30 nm, a long-range epitaxial relationship between SBTi(124) and LNO(110) facets was proposed. The epitaxial relationship was demonstrated based on the crystal structures of SBTi and LNO.Comment: 11 pages, 4 figures, published in Journal of Materials Science: Materials in Electronics (JMSE), 19 (2008), 1031-103

The Cyborg Astrobiologist: Testing a Novelty-Detection Algorithm on Two Mobile Exploration Systems at Rivas Vaciamadrid in Spain and at the Mars Desert Research Station in Utah

(ABRIDGED) In previous work, two platforms have been developed for testing computer-vision algorithms for robotic planetary exploration (McGuire et al. 2004b,2005; Bartolo et al. 2007). The wearable-computer platform has been tested at geological and astrobiological field sites in Spain (Rivas Vaciamadrid and Riba de Santiuste), and the phone-camera has been tested at a geological field site in Malta. In this work, we (i) apply a Hopfield neural-network algorithm for novelty detection based upon color, (ii) integrate a field-capable digital microscope on the wearable computer platform, (iii) test this novelty detection with the digital microscope at Rivas Vaciamadrid, (iv) develop a Bluetooth communication mode for the phone-camera platform, in order to allow access to a mobile processing computer at the field sites, and (v) test the novelty detection on the Bluetooth-enabled phone-camera connected to a netbook computer at the Mars Desert Research Station in Utah. This systems engineering and field testing have together allowed us to develop a real-time computer-vision system that is capable, for example, of identifying lichens as novel within a series of images acquired in semi-arid desert environments. We acquired sequences of images of geologic outcrops in Utah and Spain consisting of various rock types and colors to test this algorithm. The algorithm robustly recognized previously-observed units by their color, while requiring only a single image or a few images to learn colors as familiar, demonstrating its fast learning capability.Comment: 28 pages, 12 figures, accepted for publication in the International Journal of Astrobiolog

Implications of Recent Measurements of Hadronic Charmless B Decays

Implications of recent CLEO measurements of hadronic charmless B decays are discussed. (i) Employing the Bauer-Stech-Wirbel (BSW) model for form factors as a benchmark, the $B\to\pi^+\pi^-$ data indicate that the form factor $F_0^{B\pi}(0)$ is smaller than that predicted by the BSW model, whereas the data of $B\to\omega\pi, K^*\eta$ imply that the form factors $A_0^{B\omega}(0), A_0^{BK^*}(0)$ are greater than the BSW model's values. (ii) The tree-dominated modes $B\to\pi^+\pi^-, \rho^0\pi^\pm, \omega\pi^\pm$ imply that the effective number of colors N_c(LL) for (V-A)(V-A) operators is preferred to be smaller, while the current limit on $B\to\phi K$ shows that N_c(LR)>3. The data of $B\to K\eta'$ and $K^*\eta$ clearly indicate that $N_c(LR)\gg N_c(LL)$. (iii) In order to understand the observed suppression of $\pi^+\pi^-$ and non-suppression of $K\pi$ modes, both being governed by the form factor $F_0^{B\pi}$, the unitarity angle $\gamma$ is preferred to be greater than $90^\circ$. By contrast, the new measurement of $B^\pm\to\rho^0\pi^\pm$ no longer strongly favors $\cos\gamma<0$. (iv) The observed pattern K^-\pi^+\sim \ov K^0\pi^-\sim {2\over 3}K^-\pi^0 is consistent with the theoretical expectation: The constructive interference between electroweak and QCD penguin diagrams in the $K^-\pi^0$ mode explains why {\cal B}(B^-\to K^-\pi^0)>{1\over 2}{\cal B}(\ov B^0\to K^-\pi^+). (v) The observation \nc(LL)<3<\nc(LR) and our preference for \nc(LL)\sim 2 and \nc(LR)\sim 6 are justified by a recent perturbative QCD calculation of hadronic rare B decays in the heavy quark limit.Comment: 21 pages; CLEO measurements of several charmless B decay modes are updated. Discussion of the unitarity angle gamma in the \rho\pi mode is revise

Grain-filling rate improves physical grain quality in barley under heat stress conditions during the grain-filling period

Heat stress is a primary constraint to Australia's barley production. In addition to impacting grain yield, it adversely affects physical grain quality (weight and plumpness) and market value. The incidence of heat stress during grain filling is rising with global warming. However, breeding for new superior heat-tolerant genotypes has been challenging due to the narrow window of sensitivity, the unpredictable nature of heat stress, and its frequent co-occurrence with drought stress. Greater scientific knowledge regarding traits and mechanisms associated with heat tolerance would help develop more efficient selection methods. Our objective was to assess 157 barley varieties of contrasting genetic backgrounds for various developmental, agro-morphological, and physiological traits to examine the effects of heat stress on physical grain quality. Delayed sowing (i.e., July and August) increased the likelihood of daytime temperatures above 30°C during grain-filling. Supplementary irrigation of field trials ensured a reduced impact of drought stress. Heat tolerance appeared to be the primary factor determining grain plumpness. A wide variation was observed for heat tolerance, particularly among the Australian varieties. Genotypic variation was also observed for grain weight, plumpness, grain growth components, stay-green and stem water-soluble carbohydrates (WSC) content, and mobilisation under normal and delayed sown conditions. Compared to normal sowing, delayed sowing reduced duration of developmental phases, plant height, leaf size, head length, head weight, grain number, plumpness, grain width and thickness, stem WSC content, green leaf area retention, and harvest index (HI), and increased screenings, grain length, grain-filling rate (GFR), WSC mobilisation efficiency (WSCME), and grain protein content. Overall, genotypes with heavier and plumper grains under high temperatures had higher GFR, longer grain-filling duration, longer green leaf area retention, higher WSCME, taller stature, smaller leaf size, greater HI, higher grain weight/plumpness potentials, and earlier flowering. GFR played a significant role in determining barley grain weight and plumpness under heat-stress conditions. Enhancing GFR may provide a new avenue for improving heat tolerance in barley

On the Crepant Resolution Conjecture in the Local Case

In this paper we analyze four examples of birational transformations between local Calabi-Yau 3-folds: two crepant resolutions, a crepant partial resolution, and a flop. We study the effect of these transformations on genus-zero Gromov-Witten invariants, proving the Coates-Corti-Iritani-Tseng/Ruan form of the Crepant Resolution Conjecture in each case. Our results suggest that this form of the Crepant Resolution Conjecture may also hold for more general crepant birational transformations. They also suggest that Ruan's original Crepant Resolution Conjecture should be modified, by including appropriate "quantum corrections", and that there is no straightforward generalization of either Ruan's original Conjecture or the Cohomological Crepant Resolution Conjecture to the case of crepant partial resolutions. Our methods are based on mirror symmetry for toric orbifolds.Comment: 27 pages. This is a substantially revised and shortened version of my preprint "Wall-Crossings in Toric Gromov-Witten Theory II: Local Examples"; all results contained here are also proved there. To appear in Communications in Mathematical Physic

Differential effect of the focal adhesion kinase Y397F mutant on v-Src-stimulated cell invasion and tumor growth

Upon cell adhesion to extracellular matrix proteins, focal adhesion kinase (FAK) rapidly undergoes autophosphorylation on its Tyr-397 which consequently serves as a binding site for the Src homology 2 domains of the Src family protein kinases and several other intracellular signaling molecules. In this study, we have attempted to examine the effect of the FAK Y397F mutant on v- Src- stimulated cell transformation by establishing an inducible expression of the Y397F mutant in v-Src-transformed FAK-null (FAK(-/-)) mouse embryo fibroblasts. We found that the FAK Y397F mutant had both positive and negative effects on v- Src- stimulated cell transformation; it promoted v- Src- stimulated invasion, but on the other hand it inhibited the v-Src-stimulated anchorage-independent cell growth in vitro and tumor formation in vivo. The positive e. ect of the Y397F mutant on v-Src- stimulated invasion was correlated with an increased expression of matrix metalloproteinase-2, both of which were inhibited by the specific phosphatidylinositol 3-kinase inhibitor wortmannin or a dominant negative mutant of AKT, suggesting a critical role for the phosphatidylinositol 3-kinase/AKT pathway in both events. However, the expression of the Y397F mutant rendered v- Src- transformed FAK(-/-) cells susceptible to anoikis, correlated with suppression on v-Src-stimulated activation of ERK and AKT. In addition, under anoikis stress, the induction of the Y397F mutant in v- Src- transformed FAK(-/-) cells selectively led to a decrease in the level of p130(Cas), but not other focal adhesion proteins such as talin, vinculin, and paxillin. These results suggest that FAK may increase the susceptibility of v- Src- transformed cells to anoikis by modulating the level of p130(Cas)

Smooth Particle Hydrodynamics-Based Characteristics of a Shaped Jet from Different Materials

The liner material is one of the key factors in the design of armor-piercing ammunition that effect the penetration efficiency. The performance of a shaped jet formed by the charge liner is determined by different properties of the material under the blasting action, in particular for the target with explosive reactive armor, which diminishes the penetration power by dispersing the shaped jet. The performance of shaped jet elements from different materials is studied, AUTODYN finite element software and smooth particle hydrodynamics method are employed to simulate the formation of shaped jet elements from the three materials: Cu, PTFE, and PTFE/Cu and their penetration into target plates, which was verified in the experiment. A shaped jet for a Cu liner is shown to be formed under the action of a detonation wave, while PTFE and PTFE/Cu materials generate a dispersive particle jet. The head velocity of a Cu jet is found to be the lowest, the penetration depth is the deepest, and the penetration hole size is the smallest; the velocity of a PTFE particle jet is the highest and the penetration depth is the shallowest, the penetration hole size takes the mid-position; the head velocity and penetration depth of a PTFE/Cu jet take the mid-position, while the penetration hole is the largest. The PTFE/Cu jet possesses higher penetration performance as compared to the PTFE jet, and its hole-opening capability is improved as compared to the Cu jet.Облицовочный материал один из ключевых факторов при создании бронебойных боеприпасов, оказывающий влияние на эффективность внедрения. Работоспособность кумулятивного заряда, формируемого его облицовкой, определяется различными свойствами материала в условиях взрывной нагрузки, в частности для мишени с элементами динамической защиты, которые уменьшают проникающую способность, рассеивая кумулятивный заряд. Изучены рабочие характеристики элементов кумулятивного заряда из различных материалов. Конечноэлементное программное обеспечение AUTODYN и метод гидродинамики гладких частиц используются при моделировании формирования этих элементов и их внедрении в пластинымишени из трех материалов: Cu, ПТФЭ и ПТФЭ/Сu, что было проверено экспериментально. Показано, что кумулятивный заряд для медной облицовки формируется под действием детонационной волны, тогда как ПТФЭ и ПТФЭ/Cu материалы генерируют струю распыленных частиц. Установлено, что в головной части скорость струи частиц Сu наименьшая, глубина внедрения наибольшая, а размер отверстий наименьший, скорость струи частиц ПТФЭ наибольшая, глубина внедрения наименьшая, размер отверстий занимает среднее положение, скорость и глубина внедрения струи частиц ПТФЭ/Сu занимают среднее положение, тогда как отверстия имеют наибольший размер. Струя частиц ПТФЭ/Сu обладает более высокой эффективностью внедрения по сравнению со струей ПТФЭ, а ее проникающая способность выше, чем струи Cu.Облицювальний матеріал - один з ключових чинників при створенні бронебійних боєприпасів, який впливає на ефективність заглиблення. Працездатність кумулятивного заряду, який формується його облицюванням, визначається різними властивостями матеріалу в умовах вибухового навантаження, зокрема для мішені з елементами динамічного захисту, які зменшують проникаючу здатність, розсіюючи кумулятивний заряд. Вивчено робочі характеристики елементів кумулятивного заряду з різних матеріалів. Скінчнноелементне програмне забезпечення AUTODYN і метод гідродинаміки гладких частинок використовуються при моделюванні формування цих елементів і їх впровадженні в пластини-мішені з трьох матеріалів: Cu, ПТФЕ і ПТФЕ / Cu, що було перевірено експериментально. Показано, що кумулятивний заряд для мідного облицювання формується під дією детонаційної хвилі, тоді як ПТФЕ і ПТФЕ / Cu матеріали генерують струмінь розпорошених частинок. Встановлено, що в головній частині швидкість струменя частинок Cu найменша, глибина заглиблення найбільша, а розмір отворів менший, швидкість струменя частинок ПТФЕ найбільша, глибина заглиблення найменша, розмір отворів займає середнє положення, швидкість і глибина заглиблення струменя частинок ПТФЕ / Cu займають середнє положення, тоді як отвори мають найбільший розмір. Струмінь частинок ПТФЕ / Cu володіє більш високою ефективністю заглиблення в порівнянні зі струменем ПТФЕ, а її проникаюча здатність вище, ніж струменя Cu