Rules Of Thumb For Balance Of Payments Accounting

Balance of payments accounting can be confusing for students, because it is sometimes difficult to determine whether a certain transaction (e.g., a currency exchange) is a debit or a credit to a certain account.  It is therefore the purpose of this paper to summarize the standard balance of payments concepts according to useful rules of thumb, which are intended to help students more easily determine how a given international transaction affects each balance of payment account

Energy-Aware Path Planning for Fixed-Wing Seaplane UAVs

Fixed-wing unmanned aerial vehicles (UAVs) are commonly used for remote sensing applications over water bodies, such as monitoring water quality or tracking harmful algal blooms. However, there are some types of measurements that are difficult to accurately obtain from the air. In existing work, water samples have been collected in situ either by hand, with an unmanned surface vehicle (USV), or with a vertical takeoff and landing (VTOL) UAV such as a multirotor. We propose a path planner, landing control algorithm, and energy estimator that will allow a low-cost and energy efficient fixed-wing UAV to carry out a combined remote sensing and direct water sampling mission without requiring sophisticated sensors and using limited onboard computation. Finally, we demonstrate a fully autonomous mission on a modified off-the-shelf RC aircraft. The aircraft flies a survey pattern, lands at a series of sampling points and then returns to the starting location while respecting the available energy budget. In our experiments, we completed multiple sampling missions in the real world with no aborted landings or crashes and an overall energy estimation error of approximately 5%

Scandium triflate catalyzed ester synthesis using primary amides

AbstractA scandium triflate (ScOTf)3 catalyzed methodology has been developed to synthesize esters from primary amides. Various primary and secondary aliphatic alcohols have been shown to react in n-heptane with a range of primary amides for 24h

Survival of patients undergoing surgery for metastatic spinal tumours and the impact of surgical site infection

Background Patients with metastatic spinal tumours have a limited prognosis. Surgical complications which may result in prolonged hospitalisation or readmission are highly undesirable. Surgical site infection (SSI) is one such complication which can, in extreme cases, lead to death. Aim To assess the impact of SSI on patient survival after surgery for spinal metastases. Methods Demographic, operative and survival data were collected on 152 patients undergoing surgery for spinal metastases at Salford Royal NHS Foundation Trust. American Society of Anesthesiologists (ASA) grade and the Revised To kuhashi Score (RTS) were obtained as measures of health status at baseline. A semi-parametric Cox proportional hazards survival analysis was used to assess the relationships between covariates and survival. Results Mean age at operation was 60.5 years (standard deviation 12.9 years). Seventeen patients (11.2%) experienced SSI. At the time of last follow up, 117 patients had died. RTS score (p<0.001; hazard ratio 0.82; 95% confidence interval: 0.76-0.87) and ASA grade (p=0.022; hazard ratio 1.40; 95% confidence interval: 1.05-1.87) were significantly associated with survival, with better survival found in patients with higher RTS and lower ASA scores. Infection status was of substantive importance, with better survival in those without SSI (p=0.075). Age was not substantively related to survival (p=0.299). Overall, median survival time from operation was 262 days (95% confidence interval: 190-334 days). Conclusions Five-year survival in patients undergoing surgery for spinal metastases is approximately 23%. Either or both of RTS or ASA scores can be used as indicators of patient survival. There is insufficient evidence to conclude that the presence of SSI retards survival

Quantum Separability and Entanglement Detection via Entanglement-Witness Search and Global Optimization

We focus on determining the separability of an unknown bipartite quantum state $\rho$ by invoking a sufficiently large subset of all possible entanglement witnesses given the expected value of each element of a set of mutually orthogonal observables. We review the concept of an entanglement witness from the geometrical point of view and use this geometry to show that the set of separable states is not a polytope and to characterize the class of entanglement witnesses (observables) that detect entangled states on opposite sides of the set of separable states. All this serves to motivate a classical algorithm which, given the expected values of a subset of an orthogonal basis of observables of an otherwise unknown quantum state, searches for an entanglement witness in the span of the subset of observables. The idea of such an algorithm, which is an efficient reduction of the quantum separability problem to a global optimization problem, was introduced in PRA 70 060303(R), where it was shown to be an improvement on the naive approach for the quantum separability problem (exhaustive search for a decomposition of the given state into a convex combination of separable states). The last section of the paper discusses in more generality such algorithms, which, in our case, assume a subroutine that computes the global maximum of a real function of several variables. Despite this, we anticipate that such algorithms will perform sufficiently well on small instances that they will render a feasible test for separability in some cases of interest (e.g. in 3-by-3 dimensional systems)

The Rate of Homogenous Nucleation of Ice in Supercooled Water.

The homogeneous freezing of water is of fundamental importance to a number of fields, including that of cloud formation. However, there is considerable scatter in homogeneous nucleation rate coefficients reported in the literature. Using a cold stage droplet system designed to minimize uncertainties in temperature measurements, we examined the freezing of over fifteen hundred pure water droplets with diameters between 4 and 24 μm. Under the assumption that nucleation occurs within the bulk of the droplet, nucleation rate coefficients fall within the spread of literature data and are in good agreement with a subset of more recent measurements. To quantify the relative importance of surface and volume nucleation in our experiments, where droplets are supported by a hydrophobic surface and surrounded by oil, comparison of droplets with different surface area to volume ratios was performed. From our experiments it is shown that in droplets larger than 6 µm diameter (between 234.6 and 236.5 K), nucleation in the interior is more important than nucleation at the surface. At smaller sizes we cannot rule out a significant contribution of surface nucleation, and in order to further constrain surface nucleation experiments with smaller droplets are necessary. Nevertheless, in our experiments, it is dominantly volume nucleation controlling the observed nucleation rate

Anthropometric Differences between HIV-Infected Individuals Prior to Antiretroviral Treatment and the General Population from 1998–2007: The AIDS Clinical Trials Group Longitudinal Linked Randomized Trials (ALLRT) Cohort and NHANES

Objective: To assess differences in body circumferences and body mass index (BMI, kg/m2) between antiretroviral treatment (ART) naïve HIV-infected and HIV-uninfected persons. Methods: Waist, arm, and thigh circumferences and BMI were measured within the ALLRT and NHANES cohorts between 1998 and 2007. ALLRT is a prospective, longitudinal study of U.S. participants enrolled in randomized HIV treatment studies conducted by the AIDS Clinical Trials Group (ACTG). NHANES is a representative group of the US population. The cohorts were analyzed in two time periods, to account for trends towards increased adiposity. Anthropometrics were displayed in percentiles by age and sex. Multiple linear regression models examined differences between cohorts. Results: ALLRT had more males (82% versus 48%, p<0.0001), more black participants (32% versus 23%, p<0.0001), and less Hispanics (21% versus 30%, p<0.0001) than NHANES. Mean BMI was smaller in ALLRT males and females compared to NHANES by 1.6–2.4 kg/m2 (p<0.0001). Mean waist and arm circumferences in both sexes and time periods were significantly smaller in ALLRT than in NHANES (p<0.0001). Mean thigh circumference in ALLRT was also smaller than NHANES among males (p<0.0001 in both time periods) and females (p = 0.01 in the early time period). Conclusions: Differences in anthropometrics existed prior to ART initiation, in this large national cohort of HIV-infected individuals, compared to a representative HIV-uninfected cohort, indicating that HIV and its complications have important effects on body shape. Further longitudinal examination of anthropometrics in this HIV-infected cohort may provide additional insight into disease risk. Trial Registration NCT00001137 at www.clinicaltrials.gov

Survival of patients undergoing surgery for metastatic spinal tumours and the impact of surgical site 2 infection

Summary Background Patients with metastatic spinal tumours have a limited prognosis. Surgical complications that may result in prolonged hospitalization or readmission are highly undesirable. Surgical site infection (SSI) is one such complication, which can, in extreme cases, lead to death. Aim To assess the impact of SSI on patient survival after surgery for spinal metastases. Methods Demographic, operative, and survival data were collected on 152 patients undergoing surgery for spinal metastasis at a large UK tertiary referral centre. American Society of Anesthesiologists (ASA) grade and the Revised Tokuhashi Score (RTS) were determined as measures of health status and prognosis, respectively, at baseline. A semi-parametric Cox proportional hazards survival analysis was used to assess the relationships between covariates and survival. Findings Seventeen patients (11.2%) experienced SSI. Overall, median survival time from operation was 262 days (95% confidence interval: 190–334 days) and 12-month survival was 42.1%. RTS (hazard ratio: 0.82; 95% confidence interval: 0.76–0.89; P < 0.001) and ASA grade (1.37; 1.03–1.82; P = 0.028) were significantly associated with survival, with better survival found in patients with higher RTS and lower ASA scores. Infection status was of substantive importance, with better survival in those without SSI (P = 0.075). Conclusion Twelve-month survival in patients undergoing surgery for spinal metastasis is ∼42%. RTS and ASA scores may be used as indicators of patient survival either in combination or individually. Whereas SSI has some negative impact on survival, a larger study sample would be needed to confirm whether this is statistically significan