Neutrons from an atmospheric nuclear explosion can be detected by sensors in orbit. Current tools for characterizing the neutron energy spectrum assume a known source and use forward transport to ...recreate the detector response. In realistic scenarios the true source is unknown, making this an inefficient, iterative approach. In contrast, the adjoint approach directly solves for the source spectrum, enabling source reconstruction. The time–energy fluence at the satellite and adjoint transport equation allow a Monte Carlo method to characterize the neutron source’s energy spectrum directly in a new model: the Space to High-Altitude Region Adjoint (SAHARA) model. A new adjoint source event estimator was developed in SAHARA to find feasible solutions to the neutron transport problem given the constraints of the adjoint environment. This work explores SAHARA’s development and performance for mono-energetic and continuous neutron energy sources. In general, the identified spectra were shifted towards energies approximately 5% lower than the true source spectra, but SAHARA was able to capture the correct spectral shapes. Continuous energy sources, including real-world sources Fat Man and Little Boy, resulted in identifiable spectra that could have been produced by the same distribution as the true sources as demonstrated by two-dimensional (2D) Kolmogorov–Smirnov tests.
Type 2 diabetes and obstructive sleep apnea (OSA) are frequently comorbid conditions. OSA is associated with increased insulin resistance, but studies of continuous positive airway pressure (CPAP) ...have shown inconsistent effects on glycemic control. However, endpoints such as hemoglobin A1c and insulin sensitivity might not reflect short-term changes in glycemic control during sleep.
We used a continuous glucose-monitoring system to measure interstitial glucose every 5 minutes during polysomnography in 20 patients with type 2 diabetes and newly diagnosed OSA. The measurements were repeated after an average of 41 days of CPAP (range 26-96 days). All patients were on a stable diet and medications. Each 30-second epoch of the polysomnogram was matched with a continuous glucose-monitoring system reading, and the sleeping glucose level was calculated as the average for all epochs scored as sleeping.
The mean sleeping glucose decreased from untreated (122.0 +/- 61.7 mg/dL) to treated (102.9 +/- 39.4 mg/dL; p = 0.03 by Wilcoxon paired rank test). The sleeping glucose was more stable after treatment, with the median SD decreasing from 20.0 to 13.0 mg/dL (p = 0.005) and the mean difference between maximum and minimum values decreasing from 88 to 57 mg/dL (p= 0.003). The change in the mean hemoglobin A1c from 7.1% to 7.2% was not significant.
Our study is limited by the lack of a control group, but the results suggest that sleeping glucose levels decrease and are more stable after patients with type 2 diabetes and OSA are treated with CPAP.
OBJECTIVE Overlapping surgery-the performance of parts of 2 or more surgical procedures at the same time by a single lead surgeon-has recently come under intense scrutiny, although data on the ...effects of overlapping procedures on patient outcomes are lacking. The authors examined the impact of overlapping surgery on complication rates in neurosurgical patients. METHODS The authors conducted a retrospective review of consecutive nonemergent neurosurgical procedures performed during the period from May 12, 2014, to May 12, 2015, by any of 5 senior neurosurgeons at a single institution who were authorized to schedule overlapping cases. Overlapping surgery was defined as any case in which 2 patients under the care of a single lead surgeon were under anesthesia at the same time for any duration. Information on patient demographics, premorbid conditions, surgical variables, and postoperative course were collected and analyzed. Primary outcome was the occurrence of any complication from the beginning of surgery to 30 days after discharge. A secondary outcome was the occurrence of a serious complication-defined as a life-threatening or life-ending event-during this same period. RESULTS One thousand eighteen patients met the inclusion criteria for the study. Of these patients, 475 (46.7%) underwent overlapping surgery. Two hundred seventy-one patients (26.6%) experienced 1 or more complications, with 134 (13.2%) suffering a serious complication. Fourteen patients in the cohort died, a rate of 1.4%. The overall complication rate was not significantly higher for overlapping cases than for nonoverlapping cases (26.3% vs 26.9%, p = 0.837), nor was the rate of serious complications (14.7% vs 11.8%, p = 0.168). After adjustments for surgery type, surgery duration, body mass index, American Society of Anesthesiologists (ASA) physical classification grade, and intraoperative blood loss, overlapping surgery remained unassociated with overall complications (OR 0.810, 95% CI 0.592-1.109, p = 0.189). Similarly, after adjustments for surgery type, surgery duration, body mass index, ASA grade, and neurological comorbidity, there was no association between overlapping surgery and serious complications (OR 0.979, 95% CI 0.661-1.449, p = 0.915). CONCLUSIONS In this cohort, patients undergoing overlapping surgery did not have an increased risk for overall complications or serious complications. Although this finding suggests that overlapping surgery can be performed safely within the appropriate framework, further investigation is needed in other specialties and at other institutions.
Anaphylaxis is a life-threatening condition with a known effective prehospital intervention: parenteral epinephrine. The National Association of EMS Physicians (NAEMSP) advocates for emergency ...medical services (EMS) providers to be allowed to carry and administer epinephrine. Some states constrain epinephrine administration by basic life support (BLS) providers to administration using epinephrine auto-injectors (EAIs), but the cost and supply of EAIs limits the ability of some EMS agencies to provide epinephrine for anaphylaxis. This literature review and consensus report describes the extant literature and the practical and policy issues related to non-EAI administration of epinephrine for anaphylaxis, and serves as a supplementary resource document for the revised NAEMSP position statement on the use of epinephrine in the out-of-hospital treatment of anaphylaxis, complementing (but not replacing) prior resource documents. The report concludes that there is some evidence that intramuscular injection of epinephrine drawn up from a vial or ampule by appropriately trained EMS providers-without limitation to specific certification levels-is safe, facilitates timely treatment of patients, and reduces costs.
OBJECTIVE Recently, overlapping surgery has been a source of controversy both in the popular press and within the academic medical community. There have been no studies examining the possible effects ...of more stringent overlapping surgery restrictions. At the authors' institution, a new policy was implemented that restricts attending surgeons from starting a second case until all critical portions of the first case that could require the attending surgeon's involvement are completed. The authors examined the impact of this policy on complication rates, neurosurgical resident education, and wait times for neurosurgical procedures. METHODS The authors performed a retrospective chart review of nonemergency neurosurgical procedures performed over two periods-from June 1, 2014, to October 31, 2014 (pre-policy change) and from June 1, 2016, to October 31, 2016 (post-policy change)-by any of 4 senior neurosurgeons at a single institution who were authorized to schedule overlapping cases. Information on preoperative evaluation, patient demographics, premorbid conditions, surgical variables, and postoperative course were collected and analyzed. RESULTS Six hundred fifty-three patients met inclusion criteria for complications analysis. Of these, 378 (57.9%) underwent surgery before the policy change. On multivariable regression analysis, neither overlapping surgery (odds ratio OR 1.072, 95% confidence interval CI 0.710-1.620) nor the overlapping surgery policy change (OR 1.057, 95% CI 0.700-1.596) was associated with overall complication rates. Similarly, neither overlapping surgery (OR 1.472, 95% CI 0.883-2.454) nor the overlapping surgery policy change (OR 1.251, 95% CI 0.748-2.091) was associated with numbers of serious complications. After the policy change, the percentage of procedures in which the senior assistant was a postresidency fellow increased significantly, from 11.9% to 34.2% (p < 0.001). In a multiple linear regression analysis of surgery wait times, patients undergoing surgery after the policy change had significantly longer delays from the decision to operate until the actual neurosurgical procedure (p < 0.001). CONCLUSIONS At the authors' institution, further restriction of overlapping surgery was not associated with a reduction in overall or serious complications. Resident involvement in neurosurgical procedures decreased significantly after the policy change, and this study suggests that wait times for neurosurgical procedures also significantly lengthened.
On 2010 January 18-19 and June 28-29, the Wide-field Infrared Survey Explorer (WISE) spacecraft imaged the Rosetta mission target, comet 67P/Churyumov-Gerasimenko. We present a preliminary analysis ...of the images, which provide a characterization of the dust environment at heliocentric distances similar to those planned for the initial spacecraft encounter, but on the outbound leg of its orbit rather than the inbound. Broadband photometry yields low levels of CO sub(2) production at a comet heliocentric distance of 3.32 AU and no detectable production at 4.18 AU. We find that at these heliocentric distances, large dust grains with mean grain diameters on the order of a millimeter or greater dominate the coma and evolve to populate the tail. This is further supported by broadband photometry centered on the nucleus, which yield an estimated differential dust particle size distribution with a power-law relation that is considerably shallower than average. We set a 3sigma upper limit constraint on the albedo of the large-grain dust at < or =, slant0.12. Our best estimate of the nucleus radius (1.82 + or - 0.20 km) and albedo (0.04 + or - 0.01) are in agreement with measurements previously reported in the literature.
OBJECTIVEOverlapping surgery remains a controversial topic in the medical community. Although numerous studies have examined the safety profile of overlapping operations, there are few data on its ...financial impact. The authors assessed direct hospital costs associated with neurosurgical operations during periods before and after a more stringent overlapping surgery policy was implemented.METHODSThe authors retrospectively reviewed the records of nonemergency neurosurgical operations that took place during the periods from June 1, 2014, to October 31, 2014 (pre-policy change), and from June 1, 2016, to October 31, 2016 (post-policy change), by any of the 4 senior neurosurgeons authorized to perform overlapping cases during both periods. Cost data as well as demographic, surgical, and hospitalization-related variables were obtained from an institutional tool, the Value-Driven Outcomes database.RESULTSA total of 625 hospitalizations met inclusion criteria for cost analysis; of these, 362 occurred prior to the policy change and 263 occurred after the change. All costs were reported as a proportion of the average total hospitalization cost for the entire cohort. There was no significant difference in mean total hospital costs between the prechange and postchange period (0.994 ± 1.237 vs 1.009 ± 0.994, p = 0.873). On multivariate linear regression analysis, neither the policy change (p = 0.582) nor the use of overlapping surgery (p = 0.273) was significantly associated with higher total hospital costs.CONCLUSIONSA more restrictive overlapping surgery policy was not associated with a reduction in the direct costs of hospitalization for neurosurgical procedures.
We report results based on mid-infrared photometry of five active main belt objects (AMBOs) detected by the Wide-field Infrared Survey Explorer (WISE) spacecraft. Four of these bodies, P/2010 R2 (La ...Sagra), 133P/Elst-Pizarro, (596) Scheila, and 176P/LINEAR, showed no signs of activity at the time of the observations, allowing the WISE detections to place firm constraints on their diameters and albedos. Geometric albedos were in the range of a few percent, and on the order of other measured comet nuclei. P/2010 A2 was observed on 2010 April 2-3, three months after its peak activity. Photometry of the coma at 12 and 22 mu m combined with ground-based visible-wavelength measurements provides constraints on the dust particle mass distribution (PMD), dlog n/dlog m, yielding power-law slope values of alpha = -0.5 + or - 0.1. This PMD is considerably more shallow than that found for other comets, in particular inbound particle fluence during the Stardust encounter of comet 81P/Wild 2. It is similar to the PMD seen for 9P/Tempel 1 in the immediate aftermath of the Deep Impact experiment. Upper limits for CO sub(2) and CO production are also provided for each AMBO and compared with revised production numbers for WISE observations of 103P/Hartley 2.
WISE/NEOWISE Observations of Comet 103P/Hartley 2 Bauer, James M; Walker, Russell G; Mainzer, A. K ...
Astrophysical journal/The Astrophysical journal,
09/2011, Letnik:
738, Številka:
2
Journal Article
Recenzirano
Odprti dostop
We report results based on mid-infrared photometry of comet 103P/Hartley 2 taken during 2010 May 4-13 (when the comet was at a heliocentric distance of 2.3 AU, and an observer distance of 2.0 AU) by ...the Wide-field Infrared Survey Explorer. Photometry of the coma at 22 Delta *mm and data from the University of Hawaii 2.2 m telescope obtained on 2010 May 22 provide constraints on the dust particle size distribution, d log n/d log m, yielding power-law slope values of alpha = --0.97 ? 0.10, steeper than that found for the inbound particle fluence during the Stardust encounter of comet 81P/Wild 2. The extracted nucleus signal at 12 Delta *mm is consistent with a body of average spherical radius of 0.6 ? 0.2 km (one standard deviation), assuming a beaming parameter of 1.2. The 4.6 Delta *mm band signal in excess of dust and nucleus reflected and thermal contributions may be attributed to carbon monoxide or carbon dioxide emission lines and provides limits and estimates of species production. Derived carbon dioxide coma production rates are 3.5(? 0.9) X 1024 molecules per second. Analyses of the trail signal present in the stacked image with an effective exposure time of 158.4 s yields optical-depth values near 9 X 10--10 at a delta mean anomaly of 0.2 deg trailing the comet nucleus, in both 12 and 22 Delta *mm bands. A minimum chi-squared analysis of the dust trail position yields a beta-parameter value of 1.0 X 10--4, consistent with a derived mean trail-grain diameter of 1.1/ Delta *r cm for grains of Delta *r g cm--3 density. This leads to a total detected trail mass of at least 4 X 1010 Delta *r kg.
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