The boiling suppression of liquid nitrogen

When He gas is injected from room temperature into boiling liquid N$_{2}$, boiling is suppressed, leaving liquid surface flat like a mirror. Although the qualitative explanation for this phenomenon is known [Minkoff G J \textit{et al}. Nature 1957;180(4599):1413-4.], it has not been studied quantitatively and comprehensively yet. In this report, we made careful simultaneous measurements of temperature and weight variation of the liquid. The results clearly indicate that the boiling suppression is caused by cooling of the liquid with "internal evaporation" of N$_{2}$ into the He bubbles.Comment: 14 pages, 7 figure

Determinants of incident vulvovaginal candidiasis in human immunodeficiency virus-positive women.

OBJECTIVE: Mucosal infections including vulvovaginal candidiasis are a common problem for women with human immunodeficiency virus (HIV) infection. Our objective was to determine which factors predict the development of symptomatic disease among HIV-infected women. MATERIALS AND METHODS: In a prospective study from 1991 to 1995, 205 HIV-positive women were evaluated every 6 months for occurrences of vulvovaginal candidiasis. Included in the study were all initially asymptomatic women, whether they were fungal-culture-positive or -negative at baseline. Excluded from the study were all women with symptomatic vulvovaginal candidiasis at the initial visit, those who developed trichomonas vaginitis at any visit, and those who used any antifungal agents. RESULTS: The risk of the development of vulvovaginal candidiasis did not differ between women who were asymptomatically colonized at baseline and those who were fungal-culture-negative. However, the risk of developing vulvovaginal candidiasis was increased 6.8 times for women with CD4 counts less than 200 cells/mm3 at baseline. CONCLUSIONS: Fungal culture is not predictive of the development of symptomatic vulvovaginal candidiasis. Women infected with HIV who have CD4 counts below 200 cells/mm3 should be monitored more carefully for vulvovaginal candidiasis

Predicting death over 8 years in a prospective cohort of HIV-infected women: the Women's Interagency HIV Study.

ObjectivesPredicting mortality in middle-aged HIV-infected (HIV+) women on antiretroviral therapies (ART) is important for understanding the impact of HIV infection. Several health indices have been used to predict mortality in women with HIV infection. We evaluated: (1) an HIV biological index, Veterans Aging Cohort Study (VACS); (2) a physical index, Fried Frailty Index (FFI); and (3) a mental health index, Center for Epidemiologic Studies-Depression (CES-D). Proportional hazards regression analyses were used to predict death and included relevant covariates.DesignProspective, observational cohort.SettingMulticentre, across six sites in the USA.Participants1385 multirace/ethnic ART-experienced HIV+ women in 2005.Primary and secondary outcomesAll deaths, AIDS deaths and non-AIDS deaths up to ~8 years from baseline.ResultsIncluded together in one model, VACS Index was the dominant, significant independent predictor of all deaths within 3 years (HR=2.20, 95% CI 1.83, 2.65, χ2=69.04, p<0.0001), and later than 3 years (HR=1.55, 95% CI 1.30, 1.84, χ2=23.88, p<0.0001); followed by FFI within 3 years (HR=2.06, 95% CI 1.19, 3.57, χ2=6.73, p=0.01) and later than 3 years (HR=2.43, 95% CI 1.58, 3.75, χ2=16.18, p=0.0001). CES-D score was not independently associated with mortality.Conclusions and relevanceThis is the first simultaneous evaluation of three common health indices in HIV+ adults. Indices reflecting physical and biological ageing were associated with death

An Approximate Dynamic Programming Approach to Urban Freight Distribution with Batch Arrivals

We study an extension of the delivery dispatching problem (DDP) with time windows, applied on LTL orders arriving at an urban consolidation center. Order properties (e.g., destination, size, dispatch window) may be highly varying, and directly distributing an incoming order batch may yield high costs. Instead, the hub operator may wait to consolidate with future arrivals. A consolidation policy is required to decide which orders to ship and which orders to hold. We model the dispatching problem as a Markov decision problem. Dynamic Programming (DP) is applied to solve toy-sized instances to optimality. For larger instances, we propose an Approximate Dynamic Programming (ADP) approach. Through numerical experiments, we show that ADP closely approximates the optimal values for small instances, and outperforms two myopic benchmark policies for larger instances. We contribute to literature by (i) formulating a DDP with dispatch windows and (ii) proposing an approach to solve this DDP

Smart Containers With Bidding Capacity: A Policy Gradient Algorithm for Semi-Cooperative Learning

Smart modular freight containers -- as propagated in the Physical Internet paradigm -- are equipped with sensors, data storage capability and intelligence that enable them to route themselves from origin to destination without manual intervention or central governance. In this self-organizing setting, containers can autonomously place bids on transport services in a spot market setting. However, for individual containers it may be difficult to learn good bidding policies due to limited observations. By sharing information and costs between one another, smart containers can jointly learn bidding policies, even though simultaneously competing for the same transport capacity. We replicate this behavior by learning stochastic bidding policies in a semi-cooperative multi agent setting. To this end, we develop a reinforcement learning algorithm based on the policy gradient framework. Numerical experiments show that sharing solely bids and acceptance decisions leads to stable bidding policies. Additional system information only marginally improves performance; individual job properties suffice to place appropriate bids. Furthermore, we find that carriers may have incentives not to share information with the smart containers. The experiments give rise to several directions for follow-up research, in particular the interaction between smart containers and transport services in self-organizing logistics.Comment: 15 page

Limiting the caesarean section rate in low risk pregnancies is key to lowering the trend of increased abdominal deliveries: an observational study

<p>Abstract</p> <p>Background</p> <p>As the rate of Caesarean sections (CS) continues to rise in Western countries, it is important to analyze the reasons for this trend and to unravel the underlying motives to perform CS. This research aims to assess the incidence and trend of CS in a population-based birth register in order to identify patient groups with an increasing risk for CS.</p> <p>Methods</p> <p>Data from the Flemish birth register 'Study Centre for Perinatal Epidemiology' (SPE) were used for this historic control comparison. Caesarean sections (CS) from the year 2000 (N = 10540) were compared with those from the year 2008 (N = 14016). By means of the Robson classification, births by Caesarean section were ordered in 10 groups according to mother - and delivery characteristics.</p> <p>Results</p> <p>Over a period of eight years, the CS rise is most prominent in women with previous sections and in nulliparous women with a term cephalic in spontaneous labor. The proportion of inductions of labor decreases in favor of elective CS, while the ongoing inductions of labor more often end in non-elective CS.</p> <p>Conclusions</p> <p>In order to turn back the current CS trend, we should focus on low-risk primiparae. Avoiding unnecessary abdominal deliveries in this group will also have a long-term effect, in that the number of repeat CS will be reduced in the future. For the purpose of self-evaluation, peer discussion on the necessity of CS, as well as accurate registration of the main indication for CS are recommended.</p

The impact of highly active antiretroviral therapy on prevalence and incidence of cervical human papillomavirus infections in HIV-positive adolescents

Abstract Background The implementation of highly active antiretroviral therapy (HAART) among HIV-positive patients results in immune reconstitution, slower progression of HIV disease, and a decrease in the occurrence of opportunistic infections. However, the impact of HAART on cervical human papillomavirus (HPV) infection, clearance, and persistence in high-risk adolescents remains controversial. Methods HIV-positive and high-risk HIV-negative female adolescents were enrolled in the Reaching for Excellence in Adolescent Care and Health (REACH) longitudinal cohort study. At each semi-annual clinical visit, cervical lavage samples were tested for 30 HPV types. Type-specific and carcinogenic risk-specific HPV prevalence and incidence were compared in 373 eligible participants: 146 HIV-negative female adolescents with a median follow-up of 721.5 [IQR: 483-1301] days and 227 HIV-positive female adolescents. Of the 227 HIV-positive participants, a fixed set (n = 100) were examined both before and after HAART initiation; 70 were examined only before HAART initiation; and 57 were examined only after HAART initiation, with overall median follow-up of 271 [IQR: 86.5-473] and 427.25 [IQR: 200-871] days respectively for before and after HAART initiation. Results Of the 373 eligible participants, 262 (70%) were infected with at least one type of HPV at baseline, and 78 of the remaining 111 (70%) became infected with at least one type of HPV by the end of the study. Overall, the incidence and prevalence of HPV types 58, 53/66, 68/70, and 31/33/35 were much higher than the established carcinogenic and HPV vaccine types 16 and 18, especially in HIV-positive females both before and after HAART initiation. Baseline prevalence for individual high-risk HPV types ranged, depending on type, from 0.7-10%, 1-17%, and 1-18% in the HIV-negative group, the HIV-positive before HAART initiation group, and the HIV-positive after HAART initiation group, respectively. Likewise, the incidence ranged, depending on HPV type, from 0.64-9.83 cases/100 PY, 3.00-12.80 cases/100 PY, and 1.49-17.05 cases/100 PY in the three groups, respectively. The patterns of each HPV type infection, clearance, and persistence did not differ considerably before or after the introduction of HAART and were clearly independent of CD4+ change within the short post-HAART follow-up period. Conclusions HAART did not immediately affect the incidence of type-specific HPV infections within a short-period follow-up; however, future studies are warranted in larger populations to evaluate HAART's impact over longer periods

Juxta-articular myxoma of the knee in a 5-year-old boy: a case report and review of the literature (2009: 12b)

Juxta-articular myxoma (JAM) is a relatively rare variant of myxoma that occurs in the vicinity of large joints. It is composed of fibroblast-like cells that produce an excessive amount of glycosaminoglycans rich in hyaluronic acid. The peak incidence is between the 3rd and 5th decades of life. In this report we describe an extremely rare case of JAM in the knee of a 5-year-old child. The clinical presentation, radiological features and histopathologic findings are described, and the relevant literature is reviewed