Damping behavior of 316L lattice structures produced by Selective Laser Melting

Selective Laser Melting is a powder-bed additive manufacturing technology that allows producing fully-dense metal objects with complex shapes and high mechanical properties. In this work, Selective Laser Melting was used to produce 316L specimens including lattice structures with the aim of exploring the possibility given by additive manufacturing technologies to produce parts with increased damping capacity, especially in relation to their weight. The internal friction of bulk and lattice specimens was measured in terms of delay between stress and deformation (i.e. tanδ) for different applied loads and frequencies. A finite element model was used to design the test and microstructure investigations were performed to support the results obtained by dynamo-mechanical tests. Keywords: Additive manufacturing, Selective Laser Melting, 316L, Lattice structure, Damping, Internal frictio

Women at work: Gender quotas, municipal elections and local spending

Gender quotas should foster women’s presence in politics, which in turn may affect local poli- cymaking. This paper investigates this mechanism, considering indicators of municipality spending in Italy as relevant policy outcomes. For identification, we rely on the time and geographic variation in the introduction of a gender quota reform by Law 215/2012. The reform affected gender composition of candidates in Italian municipal council elections, resulting in an increase of the share of female councilors of about 13.9 percentage points. Using the reform as an instrument, we estimate that a one percentage point increase in female participation in councils rises expenditure for local security by about 1% and reduces administration costs by a comparable amount, whereas evidence on the impact on other local expenditure items is mixed and not significant. Estimated effects are associated with compositional changes in terms of employment status of female councilors and are robust to endogeneity issues, to relevant sample selections and to the implications of confounding policies

Can System Truncation Speed up Ligand-Binding Calculations with Periodic Free-Energy Simulations?

We have investigated whether alchemical free-energy perturbation calculations of relative binding energies can be sped up by simulating a truncated protein. Previous studies with spherical nonperiodic systems showed that the number of simulated atoms could be reduced by a factor of 26 without affecting the calculated binding free energies by more than 0.5 kJ/mol on average (Genheden, S.; Ryde, U. J. Chem. Theory Comput. 2012, 8, 1449), leading to a 63-fold decrease in the time consumption. However, such simulations are rather slow, owing to the need of a large cutoff radius for the nonbonded interactions. Periodic simulations with the electrostatics treated by Ewald summation are much faster. Therefore, we have investigated if a similar speed-up can be obtained also for periodic simulations. Unfortunately, our results show that it is harder to truncate periodic systems and that the truncation errors are larger for these systems. In particular, residues need to be removed from the calculations, which means that atoms have to be restrained to avoid that they move in an unrealistic manner. The results strongly depend on the strength on this restraint. For the binding of seven ligands to dihydrofolate reductase and ten inhibitors of blood-clotting factor Xa, the best results are obtained with a small restraining force constant. However, the truncation errors were still significant (e.g., 1.5-2.9 kJ/mol at a truncation radius of 10 Å). Moreover, the gain in computer time was only modest. On the other hand, if the snapshots are truncated after the MD simulations, the truncation errors are small (below 0.9 kJ/mol even for a truncation radius of 10 Å). This indicates that postprocessing with a more accurate energy function (e.g., with quantum chemistry) on truncated snapshots may be a viable approach

A Two-Party System Under the Proportional Rule is Possible: Strategic Voting in the Lab

In this study, we implement a series of voting games in the laboratory to test whether a strategic voting behavior in a proportional system would arise and induce a two-party system. In each voting game, a finite number of subjects with single-peaked preferences, uniformly distributed on a 0–20 line, are asked to vote for a number within the interval 0–20. The policy outcome is the average of the chosen numbers—a realistic representation of a compromise between parties in a parliament elected through the proportional rule. Our main result shows that polarization and strategic voting occur in the proposed proportional rule scenario. Moreover, experience and information concerning the electoral outcome of the previous period drive individuals to opt for strategic voting

Internet-Based Behavioral Interventions for Obesity: An Updated Systematic Review

The objective of this systematic review is to update a previous systematic review on the effectiveness of internet-based interventions for weight loss and weight loss maintenance in overweight and obese people with new or additional studies. A literature search from 2008 to March 2010 was conducted. Studies were eligible for inclusion if: participants were adults with a body mass index ≤ 25, at least one study arm involved an internet-based intervention and the primary aims were weight loss or maintenance. Eight additional studies over the eighteen included in the previous review met the inclusion criteria. Data were extracted on sample characteristics, attrition, weight loss, duration of treatment and maintenance of weight loss. Effect sizes (Hedges g) and relative 95% confidence intervals were calculated for all two-way comparisons within each study. No attempt was made to pool the data in a meta-analysis because of the great heterogeneity of designs among studies. An examination of effect sizes show that the higher significant effects pertain studies that found a superiority of behavioral internet-based programs enhanced by features such as tailored feedback on self-monitoring of weight, eating and activity over education only internet-based interventions. However, control groups are very different among studies and this heterogeneity probably accounts for much of the variance in effect sizes. Hence, questions still remain as to the effectiveness of web-based interventions in achieving weight loss or maintenance. Implications for further research include using a “real” control group in order to make meta-analysis possible and developing multi-factorial design in order to separate components of interventions and identify which of them or patterns of them are keys to success

Primary Tumor Resection for Metastatic Colorectal, Gastric and Pancreatic Cancer Patients: In Search of Scientific Evidence to Inform Clinical Practice

The management of the primary tumor in metastatic colorectal, gastric and pancreatic cancer patients may be challenging. Indeed, primary tumor progression could be associated with severe symptoms, compromising the quality of life and the feasibility of effective systemic therapy, and might result in life-threatening complications. While retrospective series have suggested that surgery on the primary tumor may confer a survival advantage even in asymptomatic patients, randomized trials seem not to definitively support this hypothesis. We discuss the evidence for and against primary tumor resection for patients with metastatic gastrointestinal (colorectal, gastric and pancreatic) cancers treated with systemic therapies and put in context the pros and cons of the onco-surgical approach in the time of precision oncology. We also evaluate current ongoing trials on this topic, anticipating how these will influence both research and everyday practice

Ionic dialysance allows an adequate estimate of urea distribution volume in hemodialysis patients

Ionic dialysance allows an adequate estimate of urea distribution volume in hemodialysis patients.BackgroundAn adequate estimation of urea distribution volume (V) in hemodialysis patients is useful to monitor protein nutrition. Direct dialysis quantification (DDQ) is the gold standard for determining V, but it is impractical for routine use because it requires equilibrated postdialysis plasma water urea concentration. The single pool variable volume urea kinetic model (SPVV-UKM), recommended as a standard by Kidney Disease Outcomes Quality Initiative (K/DOQI), does not need a delayed postdialysis blood sample but it requires a correct estimate of dialyser urea clearance.MethodsIonic dialysance (ID) may accurately estimate dialyzer urea clearance corrected for total recirculation. Using ID as input to SPVV-UKM, correct V values are expected when end-dialysis plasma water urea concentrations are determined in the end-of-session blood sample taken with the blood pump speed reduced to 50 mL/min for two minutes (Upwt2′). The aim of this study was to determine whether the V values determined by means of SPVV-UKM, ID, and Upwt2′ (VID) are similar to those determined by the “gold standard” DDQ method (VDDQ). Eighty-two anuric hemodialysis patients were studied.ResultsVDDQ was 26.3 ± 5.2 L; VID was 26.5 ± 4.8 L. The (VID–VDDQ) difference was 0.2 ± 1.6 L, which is not statistically significant (P = 0.242). Anthropometric volume (VA) calculated using Watson equations was 33.6 ± 6.0 L. The (VA–VDDQ) difference was 7.3 ± 3.3 L, which is statistically significant (P < 0.001).ConclusionAnthropometric-based V values overestimate urea distribution volume calculated by DDQ and SPVV-UKM. ID allows adequate V values to be determined, and circumvents the problem of delayed postdialysis blood samples

Fast simulations of patient-specific haemodynamics of coronary artery bypass grafts based on a POD-Galerkin method and a vascular shape parametrization

In this work a reduced-order computational framework for the study of haemodynamics in three-dimensional patient-specific configurations of coronary artery bypass grafts dealing with a wide range of scenarios is proposed. We combine several efficient algorithms to face at the same time both the geometrical complexity involved in the description of the vascular network and the huge computational cost entailed by time dependent patient-specific flow simulations. Medical imaging procedures allow to reconstruct patient-specific configurations from clinical data. A centerlines-based parametrization is proposed to efficiently handle geometrical variations. POD-Galerkin reduced-order models are employed to cut down large computational costs. This computational framework allows to characterize blood flows for different physical and geometrical variations relevant in the clinical practice, such as stenosis factors and anastomosis variations, in a rapid and reliable way. Several numerical results are discussed, highlighting the computational performance of the proposed framework, as well as its capability to carry out sensitivity analysis studies, so far out of reach. In particular, a reduced-order simulation takes only a few minutes to run, resulting in computational savings of 99% of CPU time with respect to the full-order discretization. Moreover, the error between full-order and reduced-order solutions is also studied, and it is numerically found to be less than 1% for reduced-order solutions obtained with just O(100) online degrees of freedom. (C) 2016 Elsevier Inc. All rights reserved