To send content items to your account,
please confirm that you agree to abide by our usage policies.
If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account.
Find out more about sending content to .
To send content items to your Kindle, first ensure firstname.lastname@example.org
is added to your Approved Personal Document E-mail List under your Personal Document Settings
on the Manage Your Content and Devices page of your Amazon account. Then enter the ‘name’ part
of your Kindle email address below.
Find out more about sending to your Kindle.
Note you can select to send to either the @free.kindle.com or @kindle.com variations.
‘@free.kindle.com’ emails are free but can only be sent to your device when it is connected to wi-fi.
‘@kindle.com’ emails can be delivered even when you are not connected to wi-fi, but note that service fees apply.
OBJECTIVES/GOALS: To characterize the oncogenic potential of HNSCC cell lines harboring 17 non-canonical PIK3CA mutations. METHODS/STUDY POPULATION: Non-canonical PIK3CA mutant constructs generated via site-directed mutagenesis are subcloned into doxycycline-inducible vector pLVX-Puro. Serum-dependent HNSCC cell line (PCI-52-SD1) is then stably transfected with vectors and undergo doxycycline-induction. Cell survival is determined by depriving cells of fetal bovine serum for 72 hours and quantifying remaining cells with 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assays. Cell proliferation and migration is evaluated with colony formation assays and transwell assays respectively. RESULTS/ANTICIPATED RESULTS: To date, the survival behavior of eight non-canonical mutants was assessed. Three mutants – Q75E, V71I, and E970K – exhibited 18.7-26.7% greater survival rate relative to cells transfected with wild-type. Five mutants – R519G, Y606C, W328S, C905S, and M1040I – demonstrated survival rates that differed only by −4.3% to +6.6% relative to wild-type. We hypothesize the three activating mutants that exhibited increased survival will also demonstrate increased cell proliferation and migratory behavior whereas the three neutral mutants will not differ from control. DISCUSSION/SIGNIFICANCE OF IMPACT: Ongoing HNSCC PI3K inhibitor trials could be more effective if all PIK3CA hyperactivation mutations are known. Identifying non-canonical mutation effects could result in greater efficacy if drugs are restricted only to those with activating mutations. CONFLICT OF INTEREST DESCRIPTION: JRG and DEJ are co-inventors of cyclic STAT3 decoy and have financial interests in STAT3 Therapeutics, Inc. STAT3 Therapeutics, Inc. holds an interest in a cyclic STAT3 decoy oligonucleotide. The remaining authors declare no conflicts.
We propose the first least-order Galerkin model of an incompressible flow undergoing two successive supercritical bifurcations of Hopf and pitchfork type. A key enabler is a mean-field consideration exploiting the symmetry of the mean flow and the asymmetry of the fluctuation. These symmetries generalize mean-field theory, e.g. no assumption of slow growth rate is needed. The resulting five-dimensional Galerkin model successfully describes the phenomenogram of the fluidic pinball, a two-dimensional wake flow around a cluster of three equidistantly spaced cylinders. The corresponding transition scenario is shown to undergo two successive supercritical bifurcations, namely a Hopf and a pitchfork bifurcation on the way to chaos. The generalized mean-field Galerkin methodology may be employed to describe other transition scenarios.
We summarize our model that high frequency quasi-periodic oscillations (QPOs) both in the neutron star low mass X-ray binaries (NS-LMXBs) and black hole LMXBs may originate from magnetohydrodynamic (MHD) waves. Based on the MHD model in NS-LMXBs, the explanation of the parallel tracks is presented. The slowly varying effective surface magnetic field of a NS leads to the shift of parallel tracks of QPOs in NS-LMXBs. In the study of kilohertz (kHz) QPOs in NS-LMXBs, we obtain a simple power-law relation between the kHz QPO frequencies and the combined parameter of accretion rate and the effective surface magnetic field. Based on the MHD model in BH-LMXBs, we suggest that two stable modes of the Alfv́en waves in the accretion disks with a toroidal magnetic field may lead to the double high frequency QPOs. This model, in which the effect of the general relativity in BH-LMXBs is considered, naturally accounts for the 3:2 relation for the upper and lower frequencies of the QPOs and the relation between the BH mass and QPO frequency.
The study of emoticon use in text communication is in its early stages (Aragon, Feldman, Chen & Kroll, 2014), with even less known about how emoticons function in multilingual environments. We describe a preliminary longitudinal analysis of text communication in an online bilingual scientific work environment and demonstrate how patterns of emoticon use constitute a novel yet systematic nonverbal aspect of communication. Specifically, coordination over bilingual speakers entails reductions in emoticon diversity over time that are greater for those who communicate in their L2 than in their L1. An analogous but weaker pattern is evident for lexical diversity in L2 but not L1. We hypothesize that reductions in emoticon diversity in the L2 are likely to reflect social contributions to alignment rather than purely proficiency.
We draw parallels between emoticons in textual communication and gesture in signed language with respect to the interdependence of codes by describing two contexts under which the behavior of emoticons in textual communication resembles that of gesture in speech. Generalizing from those findings, we propose that gesture is likely characterized by a nuanced interdependence with language whether signed, spoken or texted.
Objectives: Long-term follow-up of the Caries Management System (CMS) protocol demonstrated that regular monitoring and noninvasive management of dental caries is effective in reducing the number of caries-related events over a 7-year period. This analysis complements the authors’ original economic evaluation of the CMS by re-evaluating the per-protocol cost-effectiveness of the CMS approach.
Methods: An individual patient-simulation Markov model was developed previously, based on 3-year randomized-controlled trial (RCT) data, to simulate the incidence and progression of dental caries, and resultant interventions, and to evaluate the lifetime cost-effectiveness of the CMS versus standard dental care from the Australian private dental practitioner perspective (in which the baseline age distribution was similar to that of the Australian population). The 4-year posttrial follow-up data are used to re-evaluate the long-term cost-effectiveness of the CMS in a more real-life setting.
Results: The reduction in caries risk was maintained among those practices within which the CMS protocols were adhered to. The per-protocol model appears to be reasonably accurate at predicting the risk of restorative events in the posttrial follow-up period. The per-protocol lifetime cost per restorative event avoided is AUD1,980 (USD1,409; 1 AUD = 0.71 USD).
Conclusions: The current analysis confirms that the CMS approach is both effective, when the protocols are adhered to appropriately, and cost-effective compared with standard care in the Australian private practice setting.
‘DASH for Asthma’ (n 90) was a 6-month randomized controlled trial that demonstrated potential benefits of a DASH (Dietary Approaches to Stop Hypertension) behavioural intervention for improving diet quality and asthma control by comparing intervention to usual care in adults with uncontrolled asthma. The present study examined acceptability and feasibility of the intervention from the perspective of intervention participants and lifestyle coaches.
Grounded in Social Cognitive Theory, the 3-month intensive stage, including three individual and eight group sessions, focused on diet modifications and behavioural self-regulation. The 3-month maintenance stage contained telephone consultations. Participants and lifestyle coaches completed surveys including 5-point Likert scales and open-ended questions. We analysed data using descriptive and inductive content analyses.
Forty-six intervention participants (survey response rate was 65–72 %) and two lifestyle coaches.
Participants and lifestyle coaches were highly satisfied (all mean ratings >4) with individual and group sessions. Participants identified mastery of knowledge and skills (awareness, goal setting, self-monitoring, problem solving), social learning (class members sharing experiences and ideas) and good coaching skills (reflective listening, empathy, motivational counselling) as important contributors to self-efficacy and programme satisfaction. Participants also valued personalized feedback received in individual sessions. Lifestyle coaches viewed participant engagement as a facilitator to effective sessions. Finally, participants and lifestyle coaches identified food tasting as beneficial for observational learning and facilitation of participant engagement. High class attendance and self-monitoring rate also reflected the high engagement among participants.
The DASH behavioural intervention was feasible and highly acceptable to participants with uncontrolled asthma and lifestyle coaches.
Driven by the unprecedented wealth of high quality data that is accumulating for the Frontier Fields, they are becoming some of the best-studied strong lensing clusters to date, and probably the next few years. As will be discussed intensively in this focus meeting, the FF prove transformative for many fields: from studies of the high redshift Universe, to the assembly and structure of the clusters themselves. The FF data and the extensive collaborative effort around this program will also allow us to examine and improve upon current lens modeling techniques. Strong lensing is a powerful tool for mass reconstruction of the cores of galaxy clusters of all scales, providing an estimate of the total (dark and seen) projected mass density distribution out to 0.5 Mpc. Though SL mass may be biased by contribution from structures along the line of sight, its strength is that it is relatively insensitive to assumptions on cluster baryon astrophysics and dynamical state. Like the Frontier Fields clusters, the most “famous” strong lensing clusters are at the high mass end; they lens dozens of background sources into multiple images, providing ample lensing constraints. In this talk, I will focus on how we can leverage what we learn from modeling the FF clusters in strong lensing studies of the hundreds of clusters that will be discovered in upcoming surveys. In typical clusters, unlike the Frontier Fields, the Bullet Cluster and A1689, we observe only one to a handful of background sources, and have limited lensing constraints. I will describe the limitations that such a configuration imposes on strong lens modeling, highlight measurements that are robust to the richness of lensing evidence, and address the sources of uncertainty and what sort of information can help reduce those uncertainties. This category of lensing clusters is most relevant to the wide cluster surveys of the future.
During 1997–2012 we conducted a nationwide camera-trapping survey and assessed the availability of prey and habitat for the clouded leopard Neofelis nebulosa in Taiwan. We surveyed 1,249 camera-trap sites over 113,636 camera-trap days, from the seashore to an altitude of 3,796 m and covering various types of vegetation. No clouded leopards were photographed during 128,394 camera-trap days, including at 209 sites in other studies, confirming the presumed extinction of clouded leopards in Taiwan. Assessment of the prey base revealed altitudinal distribution patterns of prey species and prey biomass. Areas at lower altitudes and with less human encroachment and hunting supported a higher prey biomass and more of the typical prey species of clouded leopards. Habitat analysis revealed 8,523 km2 of suitable habitat but this was reduced to 6,734 km2 when adjacent areas of human encroachment were subtracted. In the absence of hunting and large mammalian carnivores the major prey of clouded leopards in Taiwan, such as Formosan macaques Macaca cyclopis, Reeves's muntjacs Muntiacus reevesi, Formosan serow Capricornis swinhoei and sambar Rusa unicolor, could become over-abundant. Thus, it is important to address the cascading effect of the disappearance of top-down predator control. Our assessment indicated that, with proper regulation of hunting, habitat restoration and corridor improvement, it may be possible to reintroduce the clouded leopard.
The traditional CdCl2 passivation of CdTe is expanded by adding other chlorides such as MgCl2, NaCl, and MnCl2 into the process through a two-step passivation procedure that combines closed space sublimation step with a vapor process. This allows the possibility of forming a highly doped field at the back of the device that could act as an electron reflector that could boost device performance by directing electrons back into the absorber layer and increasing the voltage while limiting recombination at the back of the device. The effects the two-step passivation process on device performance are characterized by current-voltage measurements, and by electroluminescence and laser-beam induced current images to show the degree of device uniformity. Additionally, capacitance voltage measurements are used to study doping density, depletion width, and possible formation of a field at the back of the device.
This paper details the development of a technique to improve the minority carrier lifetime of 4H-SiC thick (≥ 100 μm) n-type epitaxial layers through multiple thermal oxidations. A steady improvement in lifetime is seen with each oxidation step, improving from a starting ambipolar carrier lifetime of 1.09 µs to 11.2 µs after 4 oxidation steps and a high-temperature anneal. This multiple-oxidation lifetime enhancement technique is compared to a single high-temperature oxidation step, and a carbon implantation followed by a high-temperature anneal, which are traditional ways to achieve high ambipolar lifetime in 4H-SiC n-type epilayers. The multiple oxidation treatment resulted in a high minimum carrier lifetime of 6 µs, compared to < 2 µs for other treatments. The implications of lifetime enhancement to high-voltage/high-current 4H-SiC power devices are also discussed.
The objective of the National Renewable Energy Laboratory’s (NREL) current three-year CdTe plan under the U.S. Department of Energy’s SunShot Initiative is to identify primary mechanisms that limit the open-circuit voltage and fill factor of polycrystalline CdTe photovoltaic (PV) devices, and develop CdTe synthesis processes and/or device designs that avoid these limitations. Part of this project relies on analysis of crystalline materials and pseudocrystalline CdTe layers where point and extended defects can be introduced sequentially without the complications of extensive impurities and grain boundaries that are typical of present polycrystalline films. The ultimate goals of the project include producing CdTe PV devices that demonstrate ≥20% conversion efficiency, while significantly improving our understanding of processes and materials capable of attaining cost goals of <$0.50 per watt. While NREL is investigating several options for the routine fabrication of high-quality CdTe layers, one pathway involves CdTe molecular beam heteroepitaxy (MBE) on Si in collaboration with the University of Illinois at Chicago. Although CdTe/Si heteroepitaxy is relatively unfamiliar to researchers in the PV community, it has been used successfully for more than 20 years to produce high-quality CdTe surfaces required for commercial production of large-area single-crystal HgCdTe infrared detectors and focal-plane arrays. The process involves chemical and thermal preparation of Si (211) wafers, followed by deposition of As-passivation and ZnTeaccommodation layers. MBE-grown CdTe layers deposited on top of this “template” have been shown to demonstrate low etch-pit density (EPD, preferably ≤ ∼5x105 cm-2) and high structural quality (full width at half maximum ∼ 60 arcs). These initial studies indicate that 10-μm-thick CdTe layers on Si are indeed epitaxial with cathodoluminescence-determined dislocation density consistent with historic EPD measurements, and that recombination rates are distinct from either as-deposited polycrystalline or crystalline materials.
This article presents the use of flexible metal foam substrates for the growth of III-nitride nanowire light emitters to tackle the inherent limitations of thin-film light emitting diodes as well as fabrication and application issues of traditional substrates. A dense packing of gallium nitride nanowires were grown on a nickel foam substrate. The nanowires grew predominantly along the a-plane direction, normal to the local surface of the nickel foam. Strong luminescence was observed from undoped GaN and InGaN quantum well light emitting diode nanowires.
Cadmium sulfide (CdS) films were deposited onto glass substrates by chemical bath deposition (CBD) from a bath containing cadmium acetate, ammonium acetate, thiourea, and ammonium hydroxide. The CdS thin films were annealed in argon (neutral atmosphere) or hydrogen (reducing atmosphere) for 1 h at various temperatures (300, 350, 400, 450 and 500 °C). The changes in optical and electrical properties of annealed treated CdS thin films were analyzed. The results showed that, the band-gap and resistivity depend on the post-deposition annealing atmosphere and temperatures. Thus, it was found that these properties of the films, were found to be affected by various processes with opposite effects, some beneficial and others unfavorable. The energy gap and resistivity for different annealing atmospheres was seen to oscillate by thermal annealing. Recrystallization, oxidation, surface passivation, sublimation and materials evaporation were found the main factors of the heat-treatment process responsible for this oscillating behavior. Annealing over 400 °C was seen to degrade the optical and electrical properties of the film.
In this paper, we demonstrate deposition methods and conditions that allow the control of the electrical properties of doped ZnTe grown by RF magnetron sputtering using both nitrogen and copper as dopants. The carrier density of the films was characterized using a van der Pauw Hall effect measurement method. We demonstrate how the concentration of nitrogen in the plasma during the growth of the film impacts the conductivity of the ZnTe films. Films with hole concentrations in excess of 1018 cm-3 and a high degree of crystallinity were successfully grown. Similarly, we demonstrate that the hole concentration in the Cu-doped ZnTe can be varied by varying the amount of copper introduced in the films. We also observe that annealing the copper doped ZnTe films increases the carrier density, whereas annealing the nitrogen doped ZnTe films causes a decrease in carrier concentration and conductivity.
Composite rods consisting of Alumina (Al2O3) and Silicon Carbide whiskers (SiCw) are used to fabricate microwave cooking racks because they effectively act as a microwave intensification system that allows cooking at much faster rates than conventional microwave ovens. The percolation behavior, electrical conductivity and dielectric properties of these materials have been reported previously. However, it has been observed that the electrical response of the extruded bars is a function of the rod length and that long rods show substantially different behavior than thinner disks cut from them. A percolation model has been proposed that describes the effect of the alignment of the semiconducting SiC whiskers and the quality of the interfaces present in the composite rods: SiC-SiC and SiC-Al2O3-SiC for example. This study was undertaken with the goal of testing out whether the response of the individual sections could be used to generate the response of the full length rods and to assess the importance of the homogeneous distribution of the SiC fillers on the resultant impedance response.
Blue light-emitting diodes (LED's), utilizing InGaN-based multi-quantum well (MQW) active regions deposited by organometallic chemical vapor epitaxy (OMVPE), are one of the fundamental building-blocks for current solid-state lighting applications. Studies [1,2] have previously been conducted to explore the optical and physical properties of the active MQW's over a variety of different OMVPE growth conditions. However, the conclusions of these papers have often been contradictory, possibly due to a limited data set or lack of understanding of the fundamental fluid dynamics and gas-phase chemistry that occurs during the deposition process.
Multi-quantum well structures grown over a range of pressures from typical low-pressure production processes at 200 Torr, up to near-atmospheric growth conditions at 700 Torr, have been investigated in this study. At all growth pressures, clear trends of gas-phase chemical reactions are observed for increased gas residence times (lower gas speeds from the injector flange and lower rotation rates) and increased V/III ratios (higher NH3 flows).
Confocal microscopy, excitation-dependent PL (PLE), and time-resolved photo-luminescence (TRPL) have been employed on these MQW structures to investigate the carrier lifetime characteristics. Confocal emission images show spatially-separated bright and dark regions. The bright regions are red-shifted in wavelength relative to the dark regions, suggesting microscopic spatial localization of high indium content regions. As the growth pressure and gas residence times are reduced, a larger difference in band-gap between bright and dark regions, longer lifetimes, and higher average PL intensities can be obtained, indicating that higher optical quality material can be realized. Optimized MQW's grown at high pressure exhibit higher PLE slope intensities and IQE characteristics than lower pressure samples. Results on simple LED structures indicate that the improvement in MQW optical quality at high pressures translates to higher output power at a 110 A/cm2 injection current density.