574 research outputs found
Closed-loop feedback control for microfluidic systems through automated capacitive fluid height sensing
Precise fluid height sensing in open-channel microfluidics has long been a desirable feature for a wide range of applications. However, performing accurate measurements of the fluid level in small-scale reservoirs (<1 mL) has proven to be an elusive goal, especially if direct fluid-sensor contact needs to be avoided. In particular, gravity-driven systems used in several microfluidic applications to establish pressure gradients and impose flow remain open-loop and largely unmonitored due to these sensing limitations. Here we present an optimized self-shielded coplanar capacitive sensor design and automated control system to provide submillimeter fluid-height resolution (∼250 μm) and control of small-scale open reservoirs without the need for direct fluid contact. Results from testing and validation of our optimized sensor and system also suggest that accurate fluid height information can be used to robustly characterize, calibrate and dynamically control a range of microfluidic systems with complex pumping mechanisms, even in cell culture conditions. Capacitive sensing technology provides a scalable and cost-effective way to enable continuous monitoring and closed-loop feedback control of fluid volumes in small-scale gravity-dominated wells in a variety of microfluidic applications.United States. Defense Advanced Research Projects Agency (Award W911NF-12-2-0039
Thermal Dust Emission from Proplyds, Unresolved Disks, and Shocks in the Orion Nebula
We present a new 11.7 micron mosaic image of the Orion nebula obtained with
T-ReCS on Gemini South. The map includes the BN/KL region, the Trapezium, and
OMC-1 South. Excluding BN/KL, we detect 91 point sources, with 27 known
proplyds and over 30 ``naked'' stars showing no extended structure in HST
images. Within the region we surveyed, 80 percent of known proplyds show
detectable emission, almost 40 percent of naked stars are detected at 11.7
micron, and the fraction of all visible sources with IR excess emission is
roughly 50 percent. Thermal dust emission from stars with no extended structure
in HST images means that they have dust disks comparable to the size of our
solar system. Proplyds and stars with IR excess show a clear anti-correlation
in their spatial distribution, with proplyds clustered close to theta1C, and
other infrared sources found farther away. We suspect that the clustered
proplyds trace the youngest 0.5 Myr age group associated with the Trapezium,
while the more uniformly-distributed sources trace the older 1-2 Myr population
of the ONC. This suggests that small disks persist for a few Myr in irradiated
environments, and hints that hierarchical sub-clustering has been important.
Within 30 arcsec of theta1C, all proplyds are detected at 11.7 micron. The star
theta1D is associated with the most prominent mid-IR dust arc in the nebula. We
propose that this arc is the consequence of theta1D being the closest member of
the Trapezium to the background cloud. Finally, we detect dust emission from HH
jets in Orion, including HH202, HH529, HH513, and HH514. This is the first
detection of mid-IR continuum emission from dust in the body of a collimated HH
jet or bow shock.Comment: accepted by AJ. 27 pages, 11 figs, 4 color figs. If you actually want
to see the figures, download this version:
ftp://origins.colorado.edu/pub/nathans/smith.trecs.pd
The MOSFIRE Deep Evolution Field (MOSDEF) Survey: Rest-Frame Optical Spectroscopy for ~1500 H-Selected Galaxies at 1.37 < z < 3.8
In this paper we present the MOSFIRE Deep Evolution Field (MOSDEF) survey.
The MOSDEF survey aims to obtain moderate-resolution (R=3000-3650) rest-frame
optical spectra (~3700-7000 Angstrom) for ~1500 galaxies at 1.37<z<3.80 in
three well-studied CANDELS fields: AEGIS, COSMOS, and GOODS-N. Targets are
selected in three redshift intervals: 1.37<z<1.70, 2.09<z<2.61, and
2.95<z<3.80, down to fixed H_AB (F160W) magnitudes of 24.0, 24.5 and 25.0,
respectively, using the photometric and spectroscopic catalogs from the 3D-HST
survey. We target both strong nebular emission lines (e.g., [OII], Hbeta,
[OIII], 5008, Halpha, [NII], and [SII]) and stellar continuum and absorption
features (e.g., Balmer lines, Ca-II H and K, Mgb, 4000 Angstrom break). Here we
present an overview of our survey, the observational strategy, the data
reduction and analysis, and the sample characteristics based on spectra
obtained during the first 24 nights. To date, we have completed 21 masks,
obtaining spectra for 591 galaxies. For ~80% of the targets we derive a robust
redshift from either emission or absorption lines. In addition, we confirm 55
additional galaxies, which were serendipitously detected. The MOSDEF galaxy
sample includes unobscured star-forming, dusty star-forming, and quiescent
galaxies and spans a wide range in stellar mass (~10^9-10^11.5 Msol) and star
formation rate (~10^0-10^3 Msol/yr). The spectroscopically confirmed sample is
roughly representative of an H-band limited galaxy sample at these redshifts.
With its large sample size, broad diversity in galaxy properties, and wealth of
available ancillary data, MOSDEF will transform our understanding of the
stellar, gaseous, metal, dust, and black hole content of galaxies during the
time when the universe was most active.Comment: Accepted for publication in ApJS; 28 pages, 19 figures; MOSDEF
spectroscopic redshifts available at
http://mosdef.astro.berkeley.edu/Downloads.htm
Model-Independent Diagnostics of Highly Reddened Milky Way Star Clusters: Age Calibration
The next generation near- and mid-infrared Galactic surveys will yield a
large number of new highly obscured star clusters. Detailed characterization of
these new objects with spectroscopy is time-consuming. Diagnostic tools that
will be able to characterize clusters based only on the available photometry
will be needed to study large samples of the newly found objects. The
brightness difference between the red clump and the main-sequence turn-off
point have been used as a model-independent age calibrator for clusters with
ages from a few 10 to 10 yr in the optical. Here we apply for the
first time the method in the near-infrared. We calibrated this difference in
-band, which is likely to be available for obscured clusters, and we apply
it to a number of test clusters with photometry comparable to the one that will
be yielded by the current or near-future surveys. The new calibration yields
reliable ages over the range of ages for which the red clump is present in
clusters. The slope of the relation is smoother than that of the corresponding
-band relation, reducing the uncertainty in the age determinations with
respect to the optical ones.Comment: 5 pages, 5 eps figure, accepted for publication in Astronomy and
Astrophysic
A meta-analysis comparing the effectiveness of alternate day fasting, the 5:2 diet, and time-restricted eating for weight loss.
OBJECTIVE
The objective of this meta-analysis was to compare the effectiveness of different intermittent fasting (IF) regimens on weight loss, in the general population, and compare these to traditional caloric energy restriction (CER).
METHODS
Three databases were searched from 2011 to June 2021 for randomized controlled trials (RCTs) that assessed weight loss and IF, including alternate day fasting (ADF), the 5:2 diet, and time-restricted eating (TRE). A random effect network analysis was used to compare the effectiveness between the three regimens. Meta-regression analysis was presented as weighted mean differences of body weight loss.
RESULTS
The exploratory random effects network analysis of 24 RCTs (n = 1768) ranked ADF as the most effective, followed by CER and TRE. The meta-analysis showed that IF regimens resulted in similar weight loss to CER (mean difference 0.26 kg, 95% CI: -0.31 to 0.84; p = 0.37). Compliance was generally high (>80%) in trials shorter than 3 months.
CONCLUSIONS
The present meta-analysis concludes that IF is comparable to CER and a promising alternative for weight loss. Among the three regimens, ADF showed the highest effectiveness for weight loss, followed by CER and TRE. Further well-powered RCTs with longer durations of intervention are required to draw solid conclusions
Keck-I MOSFIRE spectroscopy of compact star-forming galaxies at z2: High velocity dispersions in progenitors of compact quiescent galaxies
We present Keck-I MOSFIRE near-infrared spectroscopy for a sample of 13
compact star-forming galaxies (SFGs) at redshift with star
formation rates of SFR100M y and masses of
log(M/M). Their high integrated gas velocity dispersions of
=230 km s, as measured from emission
lines of H and [OIII], and the resultant
M relation and MM all
match well to those of compact quiescent galaxies at , as measured from
stellar absorption lines. Since log(M/M)
dex, these compact SFGs appear to be dynamically relaxed and more evolved,
i.e., more depleted in gas and dark matter (13\%) than their
non-compact SFG counterparts at the same epoch. Without infusion of external
gas, depletion timescales are short, less than 300 Myr. This discovery
adds another link to our new dynamical chain of evidence that compact SFGs at
are already losing gas to become the immediate progenitors of
compact quiescent galaxies by .Comment: 12 pages, 7 figures, submitted to Ap
An optical and near IR study of the old open cluster NGC 2141
We report on CCD optical (B and V passbands) and near IR (J and K bands)
observations in the region of the old open cluster NGC 2141. By combining the
two sets of photometry (500 stars in common) we derive new estimates of the
cluster fundamental parameters. We confirm that the cluster is 2.5 Gyrs old,
but, with respect to previous investigations, we obtain a slightly larger
reddening (E(B-V)=0.40), and a slightly shorter distance (3.8 kpc) from the
Sun. Finally we present Luminosity Function (LF) in the V band, which is
another age indicator. We provide a good fit for the age range inferred from
isochrones by assuming the Kroupa et al. (1993) IMF up to =5.0. We
interpret the disagreemt at fainter magnitudes as an evidence of mass
segregation.Comment: 8 pages, 8 figures, accepted for publication in Astronomy and
Astrophysic
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