Origin of line tension for a Lennard-Jones nanodroplet

The existence and origin of line tension has remained controversial in literature. To address this issue we compute the shape of Lennard-Jones nanodrops using molecular dynamics and compare them to density functional theory in the approximation of the sharp kink interface. We show that the deviation from Young's law is very small and would correspond to a typical line tension length scale (defined as line tension divided by surface tension) similar to the molecular size and decreasing with Young's angle. We propose an alternative interpretation based on the geometry of the interface at the molecular scale

Multiple Model Predictive Control on a drainage canal system

Model Predictive Control has been implemented on a large drainage canal system in the Netherlands. This water system can be represented as a reservoir with uncertain inflow due to rainfall runoff and a water level that has to be kept within a certain range by a control flow that is limited in capacity. Tests demonstrate that Model Predictive Control outperforms feedback and feedforward controls. To deal with uncertainty in the expected inflow, Multiple Model Predictive Control (MMPC) is proposed. This controller minimizes an objective function in which the risk of damage is used by applying different scenarios to multiple identical models

Photoemission investigation of the electronic structure of Fe-Pd and Fe-Pt alloys

A photoemission investigation of Fe-Pd and Fe-Pt transition-metal alloys, using ∼50–150-eV synchrotron radiation, is presented. We consider in particular the spectral distribution of Fe states when approaching the dilute limit. By means of the Cooper minimum in the 4d and 5d photoionization cross section, we identify structures that have mainly Fe minority- or Fe majority-spin character. The relative position of these peaks is discussed in terms of the covalent interaction between Fe 3d and Pd or Pt d states. Also, the strong resemblance between the distribution of Fe states in the Pd-based and in the Pt-based alloys is demonstrated. We find a consistent behavior of interacting d states towards the dilute limit. It is concluded that the Fe states that are observed in the photoemission spectra of the dilute alloys have mainly majority-spin character and are, because of the covalent interaction with host states, widely distributed over the energy range of the host d band. The Fe minority-spin band, which is centered near the Fermi level, gradually empties with increasing Fe dilution

Technical note: “Bit by bit”: a practical and general approach for evaluating model computational complexity vs. model performance

One of the main objectives of the scientific enterprise is the development of well-performing yet parsimonious models for all natural phenomena and systems. In the 21st century, scientists usually represent their models, hypotheses, and experimental observations using digital computers. Measuring performance and parsimony of computer models is therefore a key theoretical and practical challenge for 21st century science. “Performance” here refers to a model\u27s ability to reduce predictive uncertainty about an object of interest. “Parsimony” (or complexity) comprises two aspects: descriptive complexity – the size of the model itself which can be measured by the disk space it occupies – and computational complexity – the model\u27s effort to provide output. Descriptive complexity is related to inference quality and generality; computational complexity is often a practical and economic concern for limited computing resources. In this context, this paper has two distinct but related goals. The first is to propose a practical method of measuring computational complexity by utility software “Strace”, which counts the total number of memory visits while running a model on a computer. The second goal is to propose the “bit by bit” method, which combines measuring computational complexity by “Strace” and measuring model performance by information loss relative to observations, both in bit. For demonstration, we apply the “bit by bit” method to watershed models representing a wide diversity of modelling strategies (artificial neural network, auto-regressive, process-based, and others). We demonstrate that computational complexity as measured by “Strace” is sensitive to all aspects of a model, such as the size of the model itself, the input data it reads, its numerical scheme, and time stepping. We further demonstrate that for each model, the bit counts for computational complexity exceed those for performance by several orders of magnitude and that the differences among the models for both computational complexity and performance can be explained by their setup and are in accordance with expectations. We conclude that measuring computational complexity by “Strace” is practical, and it is also general in the sense that it can be applied to any model that can be run on a digital computer. We further conclude that the “bit by bit” approach is general in the sense that it measures two key aspects of a model in the single unit of bit. We suggest that it can be enhanced by additionally measuring a model\u27s descriptive complexity – also in bit

Technical note: “Bit by bit”: a practical and general approach for evaluating model computational complexity vs. model performance

One of the main objectives of the scientific enterprise is the development of well-performing yet parsimonious models for all natural phenomena and systems. In the 21st century, scientists usually represent their models, hypotheses, and experimental observations using digital computers. Measuring performance and parsimony of computer models is therefore a key theoretical and practical challenge for 21st century science. “Performance” here refers to a model’s ability to reduce predictive uncertainty about an object of interest. “Parsimony” (or complexity) comprises two aspects: descriptive complexity – the size of the model itself which can be measured by the disk space it occupies – and computational complexity – the model’s effort to provide output. Descriptive complexity is related to inference quality and generality; computational complexity is often a practical and economic concern for limited computing resources. In this context, this paper has two distinct but related goals. The first is to propose a practical method of measuring computational complexity by utility software “Strace”, which counts the total number of memory visits while running a model on a computer. The second goal is to propose the “bit by bit” method, which combines measuring computational complexity by “Strace” and measuring model performance by information loss relative to observations, both in bit. For demonstration, we apply the “bit by bit” method to watershed models representing a wide diversity of modelling strategies (artificial neural network, auto-regressive, processbased, and others). We demonstrate that computational complexity as measured by “Strace” is sensitive to all aspects of a model, such as the size of the model itself, the input data it reads, its numerical scheme, and time stepping. We further demonstrate that for each model, the bit counts for computational complexity exceed those for performance by several orders of magnitude and that the differences among the models for both computational complexity and performance can be explained by their setup and are in accordance with expectations. We conclude that measuring computational complexity by “Strace” is practical, and it is also general in the sense that it can be applied to any model that can be run on a digital computer. We further conclude that the “bit by bit” approach is general in the sense that it measures two key aspects of a model in the single unit of bit. We suggest that it can be enhanced by additionally measuring a model’s descriptive complexity – also in bit.info:eu-repo/semantics/publishedVersio

Occurrence and profiles of PCBs and PBDEs in harbour seals and harbour porpoises from the southern North Sea

Harbour porpoises (Phocoena phocoen) and harbour seals (Phoca vitulina), two representative top coastal pollution. Concentrations of sum PCBs were 1-2 orders of magnitude higher than concentrations of sum PBDEs (with median values of 23.1 μg.g- lw (lipid weight) and 12.4 μ.g-1 lw for sum PCBs and 0.33 μ.g- lw and 0.76 μ.g-1 lw for sum PBDEs in harbour seals and harbour porpoises respectively) and were highly dependent of age group and gender. For both species, the highest PCB concentrations were observed in adult males as the result of accumulation for years and years, while the highest PBDE concentrations were measured in juveniles probably due to better developed metabolic capacities for these congeners with age in adults. Results for PCBs were higher than observations in harbour seals and porpoises from other areas, while results for PBDEs were comparable indicating that the North Sea is a highly contaminated area. Relative PCB and PBDE profiles were constructed to compare metabolic capacities between harbour seals and porpoises. A higher contribution of lower chlorinated and nonpersistent congeners, such as CB 52, CB 95, CB 101, CB 118 and CB 149 indicated that harbour porpoises are unable to metabolize these compounds. Similar to PCBs, higher contributions of other PBDEs than BDE 47 were observed in harbour porpoises, suggesting that this species has difficulties to metabolize these congeners. In contrast, harbour seals showed a higher ability to metabolize PCBs and PBDEs

Optimal nutrition during the period of mechanical ventilation decreases mortality in critically ill, long-term acute female patients: a prospective observational cohort study

ABSTRACT: INTRODUCTION: Optimal nutrition for intensive care patients has been proposed to be the provision of energy as determined by indirect calorimetry, and protein provision of at least 1.2 grams/kg pre-admission weight per day. The evidence supporting these nutritional goals is based on surrogate outcomes and is not yet substantiated by patient oriented, clinically meaningful endpoints. In the present study we evaluated the effects of achieving optimal nutrition in intensive care unit (ICU) patients during their period of mechanical ventilation on mortality. METHODS: Prospective observational cohort study in a mixed medical-surgical, 28-bed intensive care unit in an academic hospital. 243 sequential mixed medical-surgical patients were enrolled on day 3 to 5 after admission if they had an expected stay of at least another 5 to 7 days. They underwent indirect calorimetry as part of routine care. Nutrition was guided by the result of indirect calorimetry and we aimed to provide at least 1.2 grams of protein/kg/day. Cumulative balances were calculated for the period of mechanical ventilation. Outcome parameters were ICU, 28-day and hospital mortality. RESULTS: In women, when corrected for weight, height, Apache II score, diagnosis category, and hyperglycaemic index, patients who reached their nutritional goals compared to those who did not, showed a hazard ratio (HR) of 0.199 for ICU mortality (confidence interval [CI] 0.048 - 0.831; P = 0.027), a HR of 0.079 for 28 day mortality (CI 0.013 - 0.467; P = 0.005) and a HR of 0.328 for hospital mortality (CI 0.113 - 0.952; P = 0.04). Achievement of energy goals whilst not reaching protein goals, did not affect ICU mortality; the HR for 28-day mortality was 0.120 (CI 0.027 - 0.528; P = 0.005) and 0.318 for hospital mortality (CI 0.107 - 0.945; P=0.039). No difference in outcome related to optimal feeding was found for men. CONCLUSIONS: Optimal nutritional therapy improves ICU, 28-day and hospital survival in female ICU patients. Female patients reaching both energy and protein goals have better outcomes than those reaching only the energy goal. In the present study men did not benefit from optimal nutritio

New type of microengine using internal combustion of hydrogen and oxygen

Microsystems become part of everyday life but their application is restricted by lack of strong and fast motors (actuators) converting energy into motion. For example, widespread internal combustion engines cannot be scaled down because combustion reactions are quenched in a small space. Here we present an actuator with the dimensions 100x100x5 um^3 that is using internal combustion of hydrogen and oxygen as part of its working cycle. Water electrolysis driven by short voltage pulses creates an extra pressure of 0.5-4 bar for a time of 100-400 us in a chamber closed by a flexible membrane. When the pulses are switched off this pressure is released even faster allowing production of mechanical work in short cycles. We provide arguments that this unexpectedly fast pressure decrease is due to spontaneous combustion of the gases in the chamber. This actuator is the first step to truly microscopic combustion engines.Comment: Paper and Supplementary Information (to appear in Scientific Reports

Use of ileostomy versus colostomy as a bridge to surgery in left-sided obstructive colon cancer:retrospective cohort study

BACKGROUND: Colorectal cancer causes the majority of large bowel obstructions and surgical resection remains the gold standard for curative treatment. There is evidence that a deviating stoma as a bridge to surgery can reduce postoperative mortality rate; however, the optimal stoma type is unclear. The aim of this study was to compare outcomes between ileostomy and colostomy as a bridge to surgery in left-sided obstructive colon cancer.METHODS: This was a national, retrospective population-based cohort study with 75 contributing hospitals. Patients with radiological left-sided obstructive colon cancer between 2009 and 2016, where a deviating stoma was used as a bridge to surgery, were included. Exclusion criteria were palliative treatment intent, perforation at presentation, emergency resection, and multivisceral resection.RESULTS: A total of 321 patients underwent a deviating stoma; 41 (12.7 per cent) ileostomies and 280 (87.2 per cent) colostomies. The ileostomy group had longer length of stay (median 13 (interquartile range (i.q.r.) 10-16) versus 9 (i.q.r. 6-14) days, P = 0.003) and more nutritional support during the bridging interval. Both groups showed similar complication rates in the bridging interval and after primary resection, including anastomotic leakage. Stoma reversal during resection was more common in the colostomy group (9 (22.0 per cent) versus 129 (46.1 per cent) for ileostomy and colostomy respectively, P = 0.006).CONCLUSION: This study demonstrated that patients having a colostomy as a bridge to surgery in left-sided obstructive colon cancer had a shorter length of stay and lower need for nutritional support. No difference in postoperative complications were found.</p

Use of ileostomy versus colostomy as a bridge to surgery in left-sided obstructive colon cancer:retrospective cohort study

BACKGROUND: Colorectal cancer causes the majority of large bowel obstructions and surgical resection remains the gold standard for curative treatment. There is evidence that a deviating stoma as a bridge to surgery can reduce postoperative mortality rate; however, the optimal stoma type is unclear. The aim of this study was to compare outcomes between ileostomy and colostomy as a bridge to surgery in left-sided obstructive colon cancer.METHODS: This was a national, retrospective population-based cohort study with 75 contributing hospitals. Patients with radiological left-sided obstructive colon cancer between 2009 and 2016, where a deviating stoma was used as a bridge to surgery, were included. Exclusion criteria were palliative treatment intent, perforation at presentation, emergency resection, and multivisceral resection.RESULTS: A total of 321 patients underwent a deviating stoma; 41 (12.7 per cent) ileostomies and 280 (87.2 per cent) colostomies. The ileostomy group had longer length of stay (median 13 (interquartile range (i.q.r.) 10-16) versus 9 (i.q.r. 6-14) days, P = 0.003) and more nutritional support during the bridging interval. Both groups showed similar complication rates in the bridging interval and after primary resection, including anastomotic leakage. Stoma reversal during resection was more common in the colostomy group (9 (22.0 per cent) versus 129 (46.1 per cent) for ileostomy and colostomy respectively, P = 0.006).CONCLUSION: This study demonstrated that patients having a colostomy as a bridge to surgery in left-sided obstructive colon cancer had a shorter length of stay and lower need for nutritional support. No difference in postoperative complications were found.</p