Low-speed dynamic model investigation of Apollo command module configurations in the Langley spin tunnel

Dynamic stability of Apollo command module with and without drogue parachutes at low subsonic speeds in spin tunne

Testing an Oxygen Demand Delivery Device

Anesthesia care providers routinely deliver supplemental O2 during monitored anesthesia care to prevent hemoglobin desaturation. The existing method of delivery, however, contributes to complications including respiratory depression and fire hazard. Patient variability also makes delivering O2 difficult. We have developed a demand oxygen delivery system that only gives oxygen during early inspiration. We designed a volunteer study to evaluate patient monitoring and to compare continuous flow to demand delivery. We hypothesized that ceasing oxygen delivery during expiration will facilitate reliable capnography in non-intubated patients. We also hypothesized that delivering oxygen on demand leads to higher alveolar oxygen concentrations and higher hemoglobin saturation. Methods: We recruited thirty healthy volunteers. We asked volunteers to lie down in a hospital bed and fitted them with a nasal cannula and a pulse oximeter. Our prototype system delivered both constant and demand oxygen delivery, one at a time, of flows between 0 and 10 L/min. Each flow rate and mode combination was delivered for two minutes. At the end of each two-minute period, oxygen flow was turned off and the expired oxygen and carbon dioxide was sampled for three breaths. Results: When using demand delivery, the observed etCO2 value was within ±0.57 mm Hg for all flow rates. When using constant mode, the error increased as the supplemental O2 flow rate increased. Statistical analysis showed no significant difference when monitoring etCO2 using demand delivery. A statistically significant (P \u3c 0.05) difference in etCO2 measurement was observed for all rates when monitoring etCO2 during constant flow. ETO2 values were significantly higher (P \u3c 0.05) during demand delivery than during continuous flow. Higher SpO2 values were also observed during demand delivery. For flow rates of 1-4 L/min, less than 40% percent of constant flow oxygen values were needed to obtain equivalent ETO2 concentrations when using demand oxygen delivery. Discussion: EtCO2 can be monitored accurately when supplemental O2 delivery is interrupted during expiration. Demand delivery is useful for delivering O2 while still ensuring accurate etCO2 readings on exhalation. Higher ETO2 concentrations and SpO2 values can be achieved using demand oxygen delivery. These findings are consistent with prior evaluation of demand oxygen delivery systems used for long-term oxygen therapy. This study has shown that our intelligent oxygen flowmeter can obtain ETO2 and SpO2 values equivalent to or higher than continuous flow oxygen delivery while providing the benefits of demand oxygen delivery including reduced operating room fire hazar

Administering Model-based Patient-specific Supplemental Oxygen Therapy

Purpose: The oxyhemoglobin dissociation curve describes the relationship between the partial pressure of oxygen and the percent of hemoglobin saturated with oxygen and varies with chemical and physical factors that differ for every patient. If variability could be determined, patient specific oxygen therapy could be administered. We have developed a procedure for characterizing variations in the oxygen dissociation curve. The purpose of this study was to validate this procedure in surgical patients. Methods: The procedure uses an automated system to alter oxygen therapy and Hill\u27s equation to fit measurements. Once measurements are gathered, the procedure uses an iterative least-squares method to determine best-fit parameters for the Hill equation. The procedure was performed on surgical patients after which model fit was assessed. Results: 39 patients participated in this study. Using patient-specific parameter values increases correlation when compared to standard values. The procedure improved the model fit of patient saturation values significantly in 19 patients. Conclusions: This paper has demonstrated a procedure for determining patient specific pulse oximeter response. This procedure determined best-fit parameters resulting in a significantly improved fit when compared to standard values. These best-fit parameters increased the coefficient of determination R2 in all cases

Task demands dissociate the effects of muscarinic M-1 receptor blockade and protein kinase C inhibition on attentional performance in rats

The cholinergic system is known to be necessary for normal attentional processing. However, the receptors and mechanisms mediating the effects of acetylcholine on attention remain unclear. Previous work in our laboratory suggested that cholinergic muscarinic receptors are critical for maintaining performance in an attention-demanding task in rats. We examined the role of the muscarinic M-1 receptor and protein kinase C (PKC), which is activated by the M-1 receptor, in attention task performance. Rats were trained in an attention-demanding task requiring discrimination of brief (500, 100, 25 ms) visual signals from trials with no signal presentation. The effects of muscarinic M-1 receptor blockade were assessed by administering dicyclomine (0-5.0 mg/kg). The effects of PKC inhibition were assessed by administering chelerythrine chloride (0-2.0 mg/kg). Dicyclomine decreased the accuracy of detecting longer signals in this attention task, including when attentional demands were increased by flashing a houselight throughout the session. Chelerythrine chloride decreased the accuracy of signal detection in the standard version of the task but not when the houselight was flashed throughout the session. The present findings indicate that muscarinic M-1 receptors are critical for maintaining performance when attentional demands are increased, and that PKC activity may contribute to some aspects of attentional performance

In Vitro Formation of Urinary Stones : Generation of Spherulites of Calcium Phosphate in Gel and Overgrowth with Calcium Oxalate Using a New Flow Model of Crystallization

Calcium phosphate (CaP) has been detected in the majority of urinary stones containing predominantly calcium oxalate (CaOx). Therefore, crystal phases of CaP might play an important role with respect to the formation of urinary calcium stones in general. Very often, CaP found in stones or tissue of human kidney occurs in the shape of small spherulites. In this paper, we report on a new flow model of crystallization (FMCG), which has been used to generate spherulites of CaP in a gel matrix of 1% agar-agar at 37°C from a supersaturated, metastable solution continuously flowing over the gel surface. Scanning electron microscopy (SEM), X-ray diffraction and microscopic Fourier transformed infrared spectroscopy (FTIR) revealed that the particles formed (diameter: up to 200 μm) consisted of a poorly crystal-line core of carbonatoapatite which was partly surrounded by a well-crystallized shell of octacalcium phosphate (OCP) showing radially oriented sheet-like structures. Subsequently, CaOx was grown on these spherulites from a flow of a correspondingly supersaturated solution conducted over the gel matrix. It could be shown by SEM that growth of calcium oxalate monohydrate (COM) was characteristically induced by the OCP shell. Radial sheet-like forms of OCP were directly continued by COM showing a certain radial orientation. The model of crystallization in gel matrices applied here should be well-suited to simulate the process of urinary stone formation under in vitro conditions

Demonstration of an online tool to assist managed care formulary evidence-based decision making: meta-analysis of topical prostaglandin analog efficacy

BACKGROUND: The purpose of this paper was to demonstrate the use of an online service for conducting a systematic review and meta-analysis of the efficacy of topical prostaglandin analogs in reducing intraocular pressure (IOP) in glaucoma and ocular hypertension. METHODS: An online service provider (Doctor Evidence) reviewed and extracted data from the peer-reviewed literature through September 2009. Randomized controlled studies of at least three months’ duration assessing at least two prostaglandin analogs in patients with primary open-angle glaucoma, ocular hypertension, or normal-tension glaucoma were included. The primary endpoint was mean IOP. Summary estimates were created using random-effects models. The Q Chi-square test was used to assess statistical heterogeneity. RESULTS: Sixteen studies satisfied the inclusion criteria and were analyzed. On average, greater IOP-lowering was seen with bimatoprost relative to latanoprost (1 mmHg, P = 0.025) and travoprost (0.8 mmHg, P = 0.033) based on mean IOP after 12–26 weeks of treatment. No statistical difference was observed in IOP-lowering between latanoprost and travoprost (P = 0.841). Findings were similar to previously published meta-analyses of topical prostaglandin analogs. CONCLUSION: Systematic reviews relying on meta-analytic techniques to create summary statistics are considered to be the “gold standard” for synthesizing evidence to support clinical decision-making. However, the process is time-consuming, labor-intensive, and outside the capability of most formulary managers. We have demonstrated the effectiveness of a commercial service that facilitates the process of conducting such reviews

Autistic Traits and Social Anxiety Predict Differential Performance on Social Cognitive Tasks in Typically Developing Young Adults

The current work examined the unique contribution that autistic traits and social anxiety have on tasks examining attention and emotion processing. In Study 1, 119 typically-developing college students completed a flanker task assessing the control of attention to target faces and away from distracting faces during emotion identification. In Study 2, 208 typically-developing college students performed a visual search task which required identification of whether a series of 8 or 16 emotional faces depicted the same or different emotions. Participants with more self-reported autistic traits performed more slowly on the flanker task in Study 1 than those with fewer autistic traits when stimuli depicted complex emotions. In Study 2, participants higher in social anxiety performed less accurately on trials showing all complex faces; participants with autistic traits showed no differences. These studies suggest that traits related to autism and to social anxiety differentially impact social cognitive processing

Coupling to haloform molecules in intercalated C60?

For field-effect-doped fullerenes it was reported that the superconducting transition temperature Tc is markedly larger for C60.2CHX_3 (X=Cl, Br) crystals, than for pure C60. Initially this was explained by the expansion of the volume per C60-molecule and the corresponding increase in the density of states at the Fermi level in the intercalated crystals. On closer examination it has, however, turned out to be unlikely that this is the mechanism behind the increase in Tc. An alternative explanation of the enhanced transition temperatures assumes that the conduction electrons not only couple to the vibrational modes of the C60-molecule, but also to the modes of the intercalated molecules. We investigate the possibility of such a coupling. We find that, assuming the ideal bulk structure of the intercalated crystal, both a coupling due to hybridization of the molecular levels, and a coupling via dipole moments should be very small. This suggests that the presence of the gate-oxide in the field-effect-devices strongly affects the structure of the fullerene crystal at the interface.Comment: 4 pages, 1 figure, to be published in PRB (rapid communication