Effect of Modifiers on the Microstructure of Rapidly Solidified AlSi10Mg Alloy

In this work, melt-spun ribbons of AlSi10Mg added with modifiers (Er, Sr, or nano-TiB2) were produced to investigate the combined effect of modification and rapid solidification on eutectic Si. The resulting eutectic microstructures are more isotropic in comparison to that of the base alloy affecting the mechanical properties of the alloys. The modification of Si morphology and supersaturation caused by the modifiers were investigated by microscopy, X-ray diffraction, and differential scanning calorimetry. Compared to melt-spun AlSi10Mg, the eutectic Si network is finer and less continuous when Er or Sr is added, and disrupted with rounded crystals dispersed in the matrix when adding nano-TiB2. The level of supersaturation decreases in the order Er–nano-TiB2–Sr. A transition from columnar Al grains at the wheel side to finer equiaxed grains at the air side was found in the unmodified ribbon and in the one containing nano-TiB2 by means of electron backscattered diffraction. The Er- and Sr-modified ribbons display equiaxed Al grains of constant size throughout their thickness. The average hardness obtained by nano-indentation tests was lower than that of AlSi10Mg. The less continuous Si network causes the hardness drop but provides more isotropic mechanical properties

Analysis of shot noise suppression in mesoscopic cavities in a magnetic field

We present a numerical investigation of shot noise suppression in mesoscopic cavities and an intuitive semiclassical explanation of the behavior observed in the presence of an orthogonal magnetic field. In particular, we conclude that the decrease of shot noise for increasing magnetic field is the result of the interplay between the diameter of classical cyclotron orbits and the width of the apertures defining the cavity. Good agreement with published experimental results is obtained, without the need of introducing fitting parameters.Comment: 5 pages, 3 figures, contents changed (final version

Mental disorders and the use of primary health care services among homeless shelter users in the Helsinki metropolitan area, Finland

Background: Homelessness is associated with increased morbidity, mortality and health care use. The aim of this study was to examine the role of mental disorders in relation to the use of 1) daytime primary health care services and 2) after hours primary health care emergency room (PHER) services among homeless shelter users in the Helsinki Metropolitan Area, Finland. Methods: The study cohort consists of all 158 homeless persons using the four shelters operating in the study area during two selected nights. The health records were analyzed over a period of 3 years prior to the sample nights and data on morbidity and primary health care visits were gathered. We used negative binomial regression to estimate the association between mental disorders and daytime visits to primary health care and after hours visits to PHERs. Results: During the 3 years the 158 homeless persons in the cohort made 1410 visits to a physician in primary health care. The cohort exhibited high rates of mental disorders, including substance use disorders (SUDs); i.e. 141 persons (89%) had a mental disorder. We found dual diagnosis, defined as SUD concurring with other mental disorder, to be strongly associated with daytime primary health care utilization (IRR 11.0, 95% CI 5.9-20.6) when compared with those without any mental disorder diagnosis. The association was somewhat weaker for those with only SUDs (IRR 4.9, 95% CI 2.5-9.9) or with only other mental disorders (IRR 5.0, 95% CI 2.4-10.8). When focusing upon the after hours visits to PHERs we observed that both dual diagnosis (IRR 14.1, 95% CI 6.3-31.2) and SUDs (11.5, 95% CI 5.7-23.3) were strongly associated with utilization of PHERs compared to those without any mental disorder. In spite of a high numbers of visits, we found undertreatment of chronic conditions such as hypertension and diabetes. Conclusions: Dual diagnosis is particularly strongly associated with primary health care daytime visits among homeless persons staying in shelters, while after hours visits to primary health care level emergency rooms are strongly associated with both dual diagnosis and SUDs. Active treatment for SUDs could reduce the amount of emergency visits made by homeless shelter users.Peer reviewe

Elective and emergency laparoscopic cholecystectomy in the elderly: our experience

BACKGROUND: We aimed to analyze outcomes of early and delayed laparoscopic cholecystectomy in the elderly in our General Surgery Division. METHODS: We analyzed 114 LC performed from the 1st of January 2008 to the 31st of December 2012 in our General Surgery division: 67 LC were performed for gallbladder stones and 47 for acute cholecystitis. RESULTS AND DISCUSSION: Comparison between Ordinary and Emergency groups showed that drain placement and post-operative hospital stay were significatively different. There were no significative differences between Early Laparoscopic Emergency Cholecystectomy (E-ELC) and Delayed Laparoscopic Emergency Cholecystectomy (D-ELC). There weren't any differences about Team's evaluation. CONCLUSION: We consider LC a safe and effective treatment for cholelitiasis and acute cholecystitis in Ordinary and Emergency setting, also in the elderly. We also demonstrate that, in our experience, LC for AC is feasible as well

Laparoscopic appendectomy in the elderly: our experience

BACKGROUND: Laparoscopic appendectomy for acute appendicitis is one of the most common surgical procedures performed in the world. We aimed to compare laparoscopic and open appendectomy in the elderly in our experience. METHODS: We performed a retrospective review of elderly patients who underwent appendectomy for acute appendicitis from 1st of January 2006 to the 31st of July 2012. We analyzed 39 appendectomies in elderly patients: 20 procedures were performed using open technique (Group O) and 19 using laparoscopic technique (Group L). RESULTS: In the analysis of intraoperative variables there was no statistically significant difference. In this study there was no statistically significant difference also in peri-operative variables. CONCLUSION: Laparoscopic appendectomy is a safe and feasible technique in acute appendicitis also in the elderly

Local behavior of p-harmonic Green's functions in metric spaces

We describe the behavior of p-harmonic Green's functions near a singularity in metric measure spaces equipped with a doubling measure and supporting a Poincar\'e inequality

Laparoscopic repair of wound defects in the elderly: our experience of 5 years

BACKGROUND: Laparoscopic approach for wound defects is a procedure that aims to reduce surgical aggressiveness against the abdominal wall by using minimal incisions and dedicated instruments. METHODS: We report our experience about clinical outcome of elderly patients undergoing laparoscopic repair for incisional hernias (Group I) and primary inguinal hernias (Group II) from June 2007 to September 2012. We analyzed preoperative and postoperative data for the laparoscopic approach in the elderly. RESULTS AND DISCUSSION: In our experience there was no significant difference in laparoscopic procedure between normalweight and overweight patients. CONCLUSIONS: Laparoscopic repair for primary inguinal hernias and incisional ventral hernias with transabdominal placement of composite mesh in the elderly achieves excellent results with lower morbidity in comparison with open surgical approaches