Vertical cavity surface emitting laser action of an all monolithic ZnO-based microcavity

We report on room temperature laser action of an all monolithic ZnO-based vertical cavity surface emitting laser (VCSEL) under optical pumping. The VCSEL structure consists of a 2{\lambda} microcavity containing 8 ZnO/Zn(0.92)Mg(0.08)O quantum wells embedded in epitaxially grown Zn(0.92)Mg(0.08)O/Zn(0.65)Mg(0.35)O distributed Bragg reflectors (DBRs). As a prerequisite, design and growth of high reflectivity DBRs based on ZnO and (Zn,Mg)O for optical devices operating in the ultraviolet and blue-green spectral range are discussed.Comment: Copyright (2011) American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics. The following article appeared in Appl. Phys. Lett. 98, 011101 (2011) and may be found at http://apl.aip.org/resource/1/applab/v98/i1/p011101_s

Direct Optimization of Robot Parameterization for Trajectory Performance

Much effort within the field of robotics has been made to study and mimic the agility of biological flight. Emulation of bat flight is particularly difficult, as bats utilize numerous independent means of control of both their inertial and aerodynamic characteristics to complete a variety of complex maneuvers. In this thesis, we investigate the viability of enabling a reduced-DoF bat robot to synthesize one such maneuver, inverted perching, by simultaneously and directly optimizing both the configuration and the trajectory of the robot. We begin with a minimal model of a flapping flight system. Noting that longitudinal inertial dynamics represent the dominant behavior for the perching of biological bats, we introduce a single additional degree of actuation: a mass that may be shifted along the longitudinal axis of our system. We use the Lagrangian method to derive the equations of motion for our model, and then construct an augmented system where design parameters, namely linkage masses, are decision variables that are constrained to a constant value. We then reduce our optimization problem to an instance of the Direct Collocation trajectory optimization method, and find the minimum-time perching robot and trajectory. Our final configuration is able to complete the perching maneuver on a similar timescale to biological bats, suggesting viability of the reduced-DoF configuration.Ope

The Impact of Engagement on Student Learning

Abstract Colleges and universities are faced with ever-increasing pressure to improve student outcomes which ultimately impact retention, perseverance, and completio

"The Practical Perforator Flap": the sural artery flap for lower extremity soft tissue reconstruction in wounds of war

Background: Sural artery perforator flaps have been described for use as both local flaps and in free tissue transfer. We present the use of this flap for compound soft tissue defects of the lower limb in civilian casualties of armed conflict in Afghanistan. Methods/results: Detailed description of the management of blast and high-velocity projectile wounds of the lower extremity with the use of local sural perforator flaps and a review of literature. Conclusions: Sural artery perforator flaps may be harvested to cover complex lower limb defects. The use of this technique is not limited

Fire tests carried out in FCH JU FireComp project, recommendations and application to safety of gas storage systems

International audienceIn the event of a fire, composite pressure vessels behave very differently from metallic ones: the material is degraded, potentially leading to a burst without significant pressure increase. Hence, such objects are, when necessary, protected from fire by using thermally-activated devices (TPRD), and standards require testing cylinder and TPRD together. The pre-normative research project FireComp aimed at understanding better the conditions which may lead to burst, through testing and simulation, and proposed an alternative way of assessing the fire performanceof composite cylinders. This approach is currently used by Air Liquide for the safety of composite bundlescarrying large amounts of hydrogen gas

Transcriptomic characterization of the larval stage in gilthead seabream (Sparus aurata) by 454 pyrosequencing

Gilthead seabream (Sparus aurata) is a teleost belonging to the family Sparidae with a high economical relevance in the Mediterranean countries. Although genomic tools have been developed in this species in order to investigate its physiology at the molecular level and consequently its culture, genomic information on post-embryonic development is still scarce. In this study, we have investigated the transcriptome of a marine teleost during the larval stage (from hatching to 60 days after hatching) by the use of 454 pyrosequencing technology. We obtained a total of 68,289 assembled contigs, representing putative transcripts, belonging to 54,606 different clusters. Comparison against all S. aurata expressed sequenced tags (ESTs) from the NCBI database revealed that up to 34,722 contigs, belonging to about 61% of gene clusters, are sequences previously not described. Contigs were annotated through an iterative Blast pipeline by comparison against databases such as NCBI RefSeq from Danio rerio, SwissProt or NCBI teleost ESTs. Our results indicate that we have enriched the number of annotated sequences for this species by more than 50% compared with previously existing databases for the gilthead seabream. Gene Ontology analysis of these novel sequences revealed that there is a statistically significant number of transcripts with key roles in larval development, differentiation, morphology, and growth. Finally, all information has been made available online through user-friendly interfaces such as GBrowse and a Blast server with a graphical frontend

Clinical and operative predictors of outcomes of carotid endarterectomy

ObjectiveThe net benefit for patients undergoing carotid endarterectomy is critically dependent on the risk of perioperative stroke and death. Information about risk factors can aid appropriate selection of patients and inform efforts to reduce complication rates. This study identifies the clinical, radiographic, surgical, and anesthesia variables that are independent predictors of deaths and stroke following carotid endarterectomy.MethodsA retrospective cohort study of patients undergoing carotid endarterectomy in 1997 and 1998 by 64 surgeons in 6 hospitals was performed (N = 1972). Detailed information on clinical, radiographic, surgical, anesthesia, and medical management variables and deaths or strokes within 30 days of surgery were abstracted from inpatient and outpatient records. Multivariate logistic regression models identified independent clinical characteristics and operative techniques associated with risk-adjusted rates of combined death and nonfatal stroke as well as all strokes.ResultsDeath or stroke occurred in 2.28% of patients without carotid symptoms, 2.93% of those with carotid transient ischemic attacks, and 7.11% of those with strokes (P < .0001). Three clinical factors increased the risk-adjusted odds of complications: stroke as the indication for surgery (odds ratio [OR], 2.84; 95% confidence interval [CI] = 1.55-5.20), presence of active coronary artery disease (OR, 3.58; 95% CI = 1.53-8.36), and contralateral carotid stenosis ≥50% (OR, 2.32; 95% CI = 1.33-4.02). Two surgical techniques reduced the risk-adjusted odds of death or stroke: use of local anesthesia (OR, 0.30; 95% CI = 0.16-0.58) and patch closure (OR, 0.43; 95% CI = 0.24-0.76).ConclusionsInformation about these risk factors may help physicians weigh the risks and benefits of carotid endarterectomy in individual patients. Two operative techniques (use of local anesthesia and patch closure) may lower the risk of death or stroke

Jejunal Amyloidoma - a rare cause of gastrointestinal bleeding

We report a case of localized amyloid tumor of the jejunum which presented with abdominal pain and gastrointestinal bleeding. We reviewed the pathophysiologic process that precipitates bleeding in this rare tumor. We also examined the documented radiologic and endoscopic features of amyloidosis of the small bowel in the light of our reported case. All with a view to add to the growing evidence on this rare tumor which will facilitate accurate diagnosis and management