420 research outputs found
MEMS-based Micro Coriolis mass flow sensor
We have realized a micromachined micro Coriolis flow sensor consisting of a silicon nitride resonant tube of 40 μm diameter and 1.2 μm wall thickness. First\ud
measurements with both gas and liquid flows have demonstrated an unprecedented\ud
mass flow resolution in the order of 10 mg/hr at a full scale range of 1 g/hr. The sensor can simultaneously be used as a density sensor
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Early Nutrition and Weight Gain in Preterm Newborns and the Risk of Retinopathy of Prematurity
Objective: To identify nutritional and weight gain limitations associated with retinopathy of prematurity (ROP) severity among very preterm newborns. Patients and Methods 1180 infants <28 weeks GA at birth with ROP examination results were grouped and analyzed by quartile of weekly total calorie, carbohydrate, protein, and lipid intake, as well as growth velocity between postnatal days 7 and 28 (adjusted for GA and birth weight Z-score). ROP was categorized by development of no, mild (<prethreshold), type 2, or type 1 ROP, as well as markers of ROP severity including stage 3 ROP, zone 1 disease, and plus disease. Associations between nutritional intake and ROP severity were compared. Results: Greater risk for Type 1 ROP (risk/95% confidence intervals) was found for infants with lowest quartile receipt of lipids (2.1/1.1, 3.8), total calories (2.2/1.4, 3.6), and carbohydrates (1.7/1.1, 2.9). Development of zone 1 ROP was associated with lipid or total calorie intake in the lowest quartile, and development of stage 3 ROP was associated with lowest quartile of total calorie intake. Growth velocity in the lowest quartile was associated with increased risk of any ROP, including type 1 ROP. Conclusion: The risk of developing severe ROP in extremely premature infants might be reduced by improving nutritional support, specifically targeting lipids and total calories, and perhaps by improving weight gain
Comparison of capillary based microflurometric assay for CD4+ T cell count estimation with dual platform Flow cytometry
The CD4+ T cell count estimation is an important monitoring tool for HIV disease progression and efficacy of anti-retroviral treatment (ART). Due to availability of ART at low cost in developing countries, quest for reliable cost effective alternative methods for CD4+ T cell count estimation has gained importance. A simple capillary-based microflurometric assay (EasyCD4 System, Guava Technology) was compared with the conventional flow cytometric assay for estimation of CD4+ T cell counts in 79 HIV infected individuals. CD4+ T cell count estimation by both the assays showed strong correlation (r = 0.938, p < 0.001, 95% CI 0.90 to 0.96). The Bland Altman plot analysis showed that the limits of variation were within agreeable limits of ± 2SD (-161 to 129 cells/mm(3)). The Easy CD4 assay showed 100% sensitivity for estimating the CD4+ T cell counts < 200 cells/mm(3 )and < 350 cells/mm(3 )and 97% sensitivity to estimate CD4+ T cell count < 500 cells/mm(3). The specificity ranged from 82 to 100%. The Kappa factor ranged from 0.735 for the CD4+ T cell counts < 350 cells/mm(3 )to 0.771 for < 500 cells/mm(3 )CD4+ T cell counts. The system works with a simple protocol, is easy to maintain and has low running cost. The system is compact and generates minimum amount of waste. Hence the EasyCD4 System could be applied for estimation of CD4+ T cell counts in resource poor settings
Enhancement of field generation via maximal atomic coherence prepared by fast adiabatic passage in Rb vapor
We have experimentally demonstrated the enhancement of coherent Raman
scattering in Rb atomic vapor by exciting atomic coherence with fractional
stimulated Raman adiabatic passage. Experimental results are in good agreement
with numerical simulations. The results support the possibility of increasing
the sensitivity of CARS by preparing atomic or molecular coherence using short
pulses
Electromagnetically induced transparency in cold 85Rb atoms trapped in the ground hyperfine F = 2 state
We report electromagnetically induced transparency (EIT) in cold 85Rb atoms,
trapped in the lower hyperfine level F = 2, of the ground state 5
(Tiwari V B \textit{et al} 2008 {\it Phys. Rev.} A {\bf 78} 063421). Two steady
state -type systems of hyperfine energy levels are investigated using
probe transitions into the levels F = 2 and F = 3 of the
excited state 5 in the presence of coupling transitions F = 3
F = 2 and F = 3 F = 3, respectively. The
effects of uncoupled magnetic sublevel transitions and coupling field's Rabi
frequency on the EIT signal from these systems are studied using a simple
theoretical model.Comment: 12 pages, 7 figure
Protease inhibitor-induced nausea and vomiting is attenuated by a peripherally acting, opioid-receptor antagonist in a rat model
<p>Abstract</p> <p>Background</p> <p>Protease inhibitors such as ritonavir can cause nausea and vomiting which is the most common reason for discontinuation. Rats react to nauseous and emetic stimuli by increasing their oral intake of non-nutritive substances like kaolin, known as pica behavior. In this study, we evaluated the effects of methylnaltrexone, a peripherally acting <it>mu</it>-opioid receptor antagonist that does not affect analgesia, on ritonavir-induced nausea and vomiting in a rat pica model.</p> <p>Results</p> <p>We observed that 24 to 48 hr after administration of oral ritonavir 20 mg/kg, kaolin consumption increased significantly in rats (<it>P </it>< 0.01). This increase was attenuated by pretreatment with an intraperitoneal injection of methylnaltrexone (0.3–3.0 mg/kg) in a dose dependent manner (<it>P </it>< 0.01) and also with naloxone (0.1–0.3 mg/kg) (<it>P </it>< 0.01). The areas under the curve for kaolin intake from time 0 to 120 hr were significantly reduced after administration of the opioid antagonists. Food intake was not significantly affected. Plasma naltrexone levels were measured after methylnaltrexone injection, and no detectable levels were found, indicating that methylnaltrexone was not demethylated in our experimental paradigm.</p> <p>Conclusion</p> <p>These results suggest that methylnaltrexone may have potential clinical utility in reducing nausea and vomiting in HIV patients who take ritonavir.</p
The dispersion of spherical droplets in source–sink flows and their relevance to the COVID-19 pandemic
In this paper, we investigate the dynamics of spherical droplets in the
presence of a source-sink pair flow field. The dynamics of the droplets is
governed by the Maxey-Riley equation with Basset-Boussinesq history term
neglected. We find that, in the absence of gravity, there are two distinct
behaviours for the droplets: small droplets cannot go further than a specific
distance, which we determine analytically, from the source before getting
pulled into the sink. Larger droplets can travel further from the source before
getting pulled into the sink by virtue of their larger inertia, and their
maximum travelled distance is determined analytically.
We investigate the effects of gravity, and we find that there are three
distinct droplet behaviours categorised by their relative sizes: small,
intermediate-sized, and large. Counterintuitively, we find that the droplets
with minimum horizontal range are neither small nor large, but of intermediate
size. Furthermore, we show that in conditions of regular human respiration,
these intermediate-sized droplets range in size from a few m to a few
hundred m. The result that such droplets have a very short range could
have important implications for the interpretation of existing data on droplet
dispersion.Comment: 14 pages, 7 figure
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