2,885 research outputs found
Cavity-Enhanced Ultrafast Transient Absorption Spectroscopy
We present a new technique using a frequency comb laser and optical cavities
for performing ultrafast transient absorption spectroscopy with improved
sensitivity. Resonantly enhancing the probe pulses, we demonstrate a
sensitivity of OD = 1 \times 10^{-9}/\sqrt{\mbox{Hz}} for averaging
times as long as 30 s per delay point (OD).
Resonantly enhancing the pump pulses allows us to produce a high excitation
fraction at high repetition-rate, so that signals can be recorded from samples
with optical densities as low as OD , or column densities molecules/cm. This high sensitivity enables new directions for
ultrafast spectroscopy
Combined Visualization and Heat Transfer Measurements for Steam Flow Condensation in Hydrophilic and Hydrophobic Mini-Gaps
Citation: Chen X, Derby MM. Combined Visualization and Heat Transfer Measurements for Steam Flow Condensation in Hydrophilic and Hydrophobic Mini-Gaps. ASME. J. Heat Transfer. 2016;138(9):091503-091503-11. doi:10.1115/1.4033496.Condensation enhancement was investigated for flow condensation in mini-channels. Simultaneous flow visualization and heat transfer experiments were conducted in 0.952-mm diameter mini-gaps. An open loop steam apparatus was constructed for a mass flux range of 50â100âkg/m2s and steam quality range of 0.2â0.8, and validated with single-phase experiments. Filmwise condensation was observed in the hydrophilic mini-gap; pressure drop and heat transfer coefficients were compared to the (Kim and Mudawar, 2013, âUniversal Approach to Predicting Heat Transfer Coefficient for Condensing Mini/Micro-Channel Flow,â Int. J. Heat Mass Transfer, 56(1â2), pp. 238â250) correlation and prediction was very good; the mean absolute error (MAE) was 20.2%. Dropwise condensation was observed in the hydrophobic mini-gap, and periodic cycles of droplet nucleation, coalescence, and departure were found at all mass fluxes. Snapshots of six typical sweeping cycles were presented, including integrated flow visualization quantitative and qualitative results combined with heat transfer coefficients. With a fixed average steam quality (xÂŻâ=â0.42), increasing mass flux from 50 to 75 to 100âkg/m2s consequently reduced average sweeping periods from 28 to 23 to 17âms and reduced droplet departure diameters from 13.7 to 12.9 to 10.3âÎźm, respectively. For these cases, condensation heat transfer coefficients increased from 154,700 to 176,500 to 194,800âW/m2 K at mass fluxes of 50, 75, and 100âkg/m2 s, respectively. Increased mass fluxes and steam quality reduced sweeping periods and droplet departure diameters, thereby reducing liquid thickness and increasing heat transfer coefficients
HBsAg-vectored DNA vaccines elicit concomitant protective responses to multiple CTL epitopes relevant in human disease.
Vaccines capable of controlling neoplastic and infectious diseases which depend on the cellular immune response for their resolution, have proven difficult to develop. We, and others, have previously demonstrated that the potent immunogenicity of hepatitis B surface antigen (HBsAg), the already- licensed human vaccine for hepatitis B infection, may be exploited to deliver foreign antigens for cytotoxic T-lymphocyte (CTL) induction. In this study we demonstrate that recombinant (r) HBsAg DNA delivering a CTL polyepitope appended at the C' terminus elicits concomitant responses to multiple epitopes restricted through a diversity of MHC class I haplotypes, which are relevant in a number of human diseases. We show that the rHBsAg DNA vaccine elicits concomitant protection against neoplastic and infectious disease. These studies vindicate the use of HBsAg as a powerful vector to deliver CTL responses to foreign antigens, and have implications for a multi-disease vaccine applicable to the HLA-polymorphic human population
Multi-method assessment of palatable food exposure in women with and without eating disorders
This is the peer reviewed version of the following article: Christensen, KA, French, MN, Chen, EY. Multi-method assessment of palatable food exposure in women with and without eating disorders. Eur Eat Disorders Rev. 2020; 28: 594â 602. https://doi.org/10.1002/erv.2746, which has been published in final form at https://doi.org/10.1002/erv.2746. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions. This article may not be enhanced, enriched or otherwise transformed into a derivative work, without express permission from Wiley or by statutory rights under applicable legislation. Copyright notices must not be removed, obscured or modified. The article must be linked to Wileyâs version of record on Wiley Online Library and any embedding, framing or otherwise making available the article or pages thereof by third parties from platforms, services and websites other than Wiley Online Library must be prohibited.Objective
Eating disorders (EDs) are characterized by dysregulated responses to palatable food. Using a multi-method approach, this study examined responses to palatable food exposure and subsequent ad libitum eating in women with binge-eating disorder (BED: n = 64), anorexia nervosa (AN: n = 16), and bulimia nervosa (BN: n = 35) and 26 healthy controls (HCs).
Method
Participants were exposed to palatable food followed by an ad libitum eating opportunity. Affective and psychophysiological responses were measured before and during the task.
Results
Participants with EDs reported greater negative affect, particularly fear, following the food cue exposure, whereas HCs reported no change. BN and BED groups reported greater urge to binge after the food cue exposure, whereas AN and HC groups reported no change.
Respiratory sinus arrhythmia levels, skin conductance and tonic skin conductance levels increased during food exposure for all groups. Across baseline and during the food exposure, the BED group had lower respiratory sinus arrhythmia levels relative to the BN and HC groups. The BED group consumed significantly more palatable food than the AN group.
Conclusions
âPalatableâ food stimuli elicited more negative affect, particularly fear, in individuals with EDs; and this, rather than psychophysiological responses, distinguishes individuals with EDs from those without
Droplet ejection and sliding on a flapping film
Citation: X. Chen, N. Doughramaji, A.R. Betz, M.M. Derby, Droplet departure and ejection on flapping films, AIP Advances, 7, 035014.Water recovery and subsequent reuse are required for human consumption as well as industrial, and agriculture applications. Moist air streams, such as cooling tower plumes and fog, represent opportunities for water harvesting. In this work, we investigate a flapping mechanism to increase droplet shedding on thin, hydrophobic films for two vibrational cases (e.g., Âą 9 mm and 11 Hz; Âą 2 mm and 100 Hz). Two main mechanisms removed water droplets from the flapping film: vibrational-induced coalescence/sliding and droplet ejection from the surface. Vibrations mobilized droplets on the flapping film, increasing the probability of coalescence with neighboring droplets leading to faster droplet growth. Droplet departure sizes of 1â2 mm were observed for flapping films,compared to 3â4 mm on stationary films, which solely relied on gravity for droplet removal. Additionally, flapping films exhibited lower percentage area coverage by water after a few seconds. The second removal mechanism, droplet ejection was analyzed with respect to surface wave formation and inertia. Smaller droplets (e.g., 1-mm diameter) were ejected at a higher frequency which is associated with a higher acceleration. Kinetic energy of the water was the largest contributor to energy required to flap the film, and low energy inputs (i.e., 3.3 W/m2) were possible. Additionally, self-flapping films could enable novel water collection and condensation with minimal energy input
A four gene signature of chromosome instability (CIN4) predicts for benefit from taxanes in the NCIC-CTG MA21 clinical trial.
Recent evidence demonstrated CIN4 as a predictive marker of anthracycline benefit in early breast cancer. An analysis of the NCIC CTG MA.21 clinical trial was performed to test the role of existing CIN gene expression signatures as prognostic and predictive markers in the context of taxane based chemotherapy.RNA was extracted from patients in cyclophosphamide, epirubicin and flurouracil (CEF) and epirubicin, cyclophosphamide and paclitaxel (EC/T) arms of the NCIC CTG MA.21 trial and analysed using NanoString technology.After multivariate analysis both high CIN25 and CIN70 score was significantly associated with an increased in RFS (HR 1.76, 95%CI 1.07-2.86, p=0.0018 and HR 1.59, 95%CI 1.12-2.25, p=0.0096 respectively). Patients whose tumours had low CIN4 gene expression scores were associated with an increase in RFS (HR: 0.64, 95% CI 0.39-1.03, p=0.06) when treated with EC/T compared to patients treated with CEF.In conclusion we have demonstrated CIN25 and CIN70 as prognostic markers in breast cancer and that CIN4 is a potential predictive maker of benefit from taxane treatment
Mass-redshift dependency of Supermassive Black Hole Binaries for the Gravitational Wave Background
Studying how the black hole (BH) - (galaxy) bulge mass relation evolves with
redshift provides valuable insights into the co-evolution of supermassive black
holes and their host galaxies. However, obtaining accurate measurement of BH
masses is challenging due to the bias towards the most massive and luminous
galaxies. We use an analytical astrophysical model with galaxy stellar mass
function, pair fraction, merger timescale and BH-bulge mass relation extended
to include redshift evolution. The model can predict the intensity of the
gravitational wave background produced by a population of supermassive black
hole binary (SMBHB) as a function of the frequency. We focus on the BH-bulge
mass relation and its variation with redshift using the EAGLE, Illustris,
TNG100, TNG300, Horizon-AGN and SIMBA large-scale cosmological simulations. By
understanding the processes and relationships concerning the formation and
co-evolution of galaxies and their central BHs we can make theoretical and
analytical expressions in order to refine current astrophysical models. This
allows us to compare the predictions of this model with the constraints of
Pulsar Timing Array observations. Here, we employ Bayesian analysis for the
parameter inference. By fitting the BH-bulge mass parameters to the Illustris
and SIMBA simulations we analyze the changes in the constraints on the other
astrophysical parameters. Furthermore, we also examine the variation in SMBHB
merger rate with mass and redshift between these large-scale simulations.Comment: 17 pages, 13 figures, 5 tables, 23 appendix figure
BioModels Database: An enhanced, curated and annotated resource for published quantitative kinetic models
Background: Quantitative models of biochemical and cellular systems are used to answer a variety of questions in the
biological sciences. The number of published quantitative models is growing steadily thanks to increasing interest in
the use of models as well as the development of improved software systems and the availability of better, cheaper
computer hardware. To maximise the benefits of this growing body of models, the field needs centralised model
repositories that will encourage, facilitate and promote model dissemination and reuse. Ideally, the models stored in
these repositories should be extensively tested and encoded in community-supported and standardised formats. In
addition, the models and their components should be cross-referenced with other resources in order to allow their
unambiguous identification.
Description: BioModels Database http://www.ebi.ac.uk/biomodels/ is aimed at addressing exactly these needs. It is a
freely-accessible online resource for storing, viewing, retrieving, and analysing published, peer-reviewed quantitative
models of biochemical and cellular systems. The structure and behaviour of each simulation model distributed by
BioModels Database are thoroughly checked; in addition, model elements are annotated with terms from controlled
vocabularies as well as linked to relevant data resources. Models can be examined online or downloaded in various
formats. Reaction network diagrams generated from the models are also available in several formats. BioModels
Database also provides features such as online simulation and the extraction of components from large scale models
into smaller submodels. Finally, the system provides a range of web services that external software systems can use to
access up-to-date data from the database.
Conclusions: BioModels Database has become a recognised reference resource for systems biology. It is being used by
the community in a variety of ways; for example, it is used to benchmark different simulation systems, and to study the
clustering of models based upon their annotations. Model deposition to the database today is advised by several
publishers of scientific journals. The models in BioModels Database are freely distributed and reusable; the underlying
software infrastructure is also available from SourceForge https://sourceforge.net/projects/biomodels/ under the GNU
General Public License
Boundary Terms, Spinors and Kerr/CFT
Similarly as in AdS/CFT, the requirement that the action for spinors be
stationary for solutions to the Dirac equation with fixed boundary conditions
determines the form of the boundary term that needs to be added to the standard
Dirac action in Kerr/CFT. We determine this boundary term and make use of it to
calculate the two-point function for spinor fields in Kerr/CFT. This two-point
function agrees with the correlator of a two dimensional relativistic conformal
field theory.Comment: 15 page
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