Gray coding for multilevel constellations in Gaussian noise

The problem of finding the optimal labeling (bit-to-symbol mapping) of multilevel coherent phase shift keying (PSK), pulse amplitude modulation (PAM), and quadrature amplitude modulation (QAM) constellations with respect to minimizing the bit-error probability (BEP) over a Gaussian channel is addressed. We show that using the binary reflected Gray code (BRGC) to label the signal constellation results in the lowest possible BEP for high enough signal energy-to-noise ratios and analyze what is "high enough"in this sense. It turns out that the BRGC is optimal for PSK and PAM systems whenever the target BEP is at most a few percent, which covers most systems of practical interest. New and simple closed-form expressions are presented for the BEP of PSK, PAM, and QAM using the BRGC. \ua9 2007 IEEE

The importance of nature in coping

The aim of the present dissertation is to create a greater understanding of the importance of pure experiences of nature for human health. The dissertation consists of five articles and a frame story. The first two articles report on an introspective study of my own experiences of the nature previously. The interplay between human beings and the natural environment is described in detail, based on the interaction between the author and strong elements in nature, e.g. stones and water. The findings from Article III and IV may be interpreted as follows: x Elderly people, in general, recover more quickly from directed attention fatigue after having rested in a garden than after having rested indoors, as could be measured by different tests of concentration. x Elderly people with low psycho-physiological balance were most affected by a stay in a garden, as could be measured by changes in heart rate and blood pressure. x The study shows, first, that an outdoor visit is important for recovery from stress and fatigue and, second, that the improvement is especially significant for those who are most susceptible. The findings from Article V may be interpreted as follows: x Experiencing nature seems to have a more powerful influence on the rehabilitation potential of people greatly affected by a crisis. x Taking a walk also has a significant influence, although not of equal importance. x The social factor seems to have more influence on the rehabilitation potential of people affected by a crisis to a low/moderate degree. x Having access to nature in everyday life can have a buffering effect on people’s mental state. Individuals who have many experiences of nature are less affected by their crisis than are those who have few such experiences. The above results are discussed and interpreted in the frame story by linking them to that stays in sound natural environments function as stays in enriched environments. Sound natural environments contain certain qualities that mediate an effectual explanatory models of the effects of nature experiences on emotions and recovery from a crisis

The future development of district heating in Gothenburg

Göteborg Energi is the sole provider of district heat in the Gothenburg region in Sweden. By the year 2030, the generation of heat in Gothenburg is planned to be free of fossil fuels. The plans include the construction of a biomass-fuelled combined heat and power plant and an increased use of bio gas. These plans are already set, but there are many possible additional measures that could be implemented in the district heating system that will help to meet the targets set for 2030. However, the future is hard to predict and it may be difficult to choose which measures to implement. In order to assess the possible measures to be implemented, an optimisation study through the software GAMS has been performed in this thesis: a model of the generation of district heating in Gothenburg has been created and 4 different scenarios where measures to decrease total system running costs have been implemented by the year 2032 have been studied. These measures are: seasonal thermal energy storage, thermal energy storage in buildings, thermal energy storage in a hot water accumulator tank and an increased use of exhaust air heat pumps in buildings. The district heating system is affected by the electric system in several ways through the price of electricity. In the future, when more electricity is generated from intermittent sources such as wind or solar, the price of electricity will be fluctuating and the district heating system must be able to handle these fluctuations. The optimisation is performed on an hourly basis and includes hourly prices for electricity that have been previously simulated for 2032. It was found that it is possible to achieve a fossil-free generation of heat in Gothenburg by 2032. The studied measures all give system cost savings in the form of reduced running costs. By introducing thermal energy storage in the district heating system, substantial savings in running costs can be achieved, as well as reduced heat load variations on both daily and seasonal levels. By using buildings as thermal energy storage, similar cost savings as for an accumulator tank can be achieved, but at much lower investment cost. A seasonal thermal energy storage will give large cost savings and heavily reduced heat load variations, but at a very high investment cost. With an increased amount of exhaust air heat pumps in buildings, the total running costs of the heat generation system can be reduced. However, these heat pumps will give a small increase in heat load variation on a system level

The Oxytocinergic System as a Mediator of Anti-stress and Instorative Effects Induced by Nature: The Calm and Connection Theory

Ever more research results demonstrate that human health and wellbeing are positively affected by stays in and/or exposure to natural areas, which leads, among other things, to a reduction in high stress levels. However, according to the studies, these natural areas must meet certain qualities. The qualities that are considered to be most health promoting are those that humans perceive in a positive way. Theories about how natural areas can reduce people's stress levels and improve their coping skills have mainly focused on how certain natural areas that are perceived as safe reduce the activity of the hypothalamic-pituitary-adrenal axis and consequent reduction of cortisol levels. This article discusses studies containing descriptions of how participants in rehabilitation perceive and react to natural phenomena. The common core variable in the analyzed studies was the experience of calm and connection, and this experience was associated with a reduction in stress levels and with being able to develop health and coping skills. We suggest that this experience provides a possible role for the oxytocinergic system to act as a physiological mediator for the positive and health-promoting effects in humans caused by nature. The theory is mainly based on analogies framed by theories and data from the fields of environmental psychology, horticulture, landscape architecture, medicine, and neuroscience. Oxytocin promotes different kinds of social interaction and bonding and exerts stress-reducing and healing effects. We propose that oxytocin is released by certain natural phenomena experienced as positive to decrease the levels of fear and stress, increase levels of trust and wellbeing, and possibly develop attachment or bonding to nature. By these effects, oxytocin will induce health-promoting effects. In situations characterized by low levels of fear and stress in response to release of oxytocin, the capacity for "growth" or psychological development might also be promoted. Such an instorative effect of nature, i.e., the capacity of nature to promote reorientation and the creation of new coping strategies, might hence represent an additional aspect of the oxytocin-linked effect profile, triggered in connection with certain nature phenomena. We conclude by proposing that the stress-relieving, health-promoting, restorative, and instorative effects of nature may involve activation of the oxytocinergic system

TCF7L2 is a master regulator of insulin production and processing

Genome-wide association studies have revealed >60 loci associated with type 2 diabetes (T2D), but the underlying causal variants and functional mechanisms remain largely elusive. Although variants in TCF7L2 confer the strongest risk of T2D among common variants by presumed effects on islet function, the molecular mechanisms are not yet well understood. Using RNA-sequencing, we have identified a TCF7L2-regulated transcriptional network responsible for its effect on insulin secretion in rodent and human pancreatic islets. ISL1 is a primary target of TCF7L2 and regulates proinsulin production and processing via MAFA, PDX1, NKX6.1, PCSK1, PCSK2 and SLC30A8, thereby providing evidence for a coordinated regulation of insulin production and processing. The risk T-allele of rs7903146 was associated with increased TCF7L2 expression, and decreased insulin content and secretion. Using gene expression profiles of 66 human pancreatic islets donors', we also show that the identified TCF7L2-ISL1 transcriptional network is regulated in a genotype-dependent manner. Taken together, these results demonstrate that not only synthesis of proinsulin is regulated by TCF7L2 but also processing and possibly clearance of proinsulin and insulin. These multiple targets in key pathways may explain why TCF7L2 has emerged as the gene showing one of the strongest associations with T2

Att mäta korruption

I denna uppsats genomförs en statistisk analys där fyra socialpolitiska teoriers förklaringskraft vad gäller förekomsten av korruption testas. Det huvudsakliga materialet utgörs av data från Quality of Government, Transparency International samt teorier från vetenskapliga artiklar. Uppsatsen är begränsad till EU-27-länderna för vilka data har sammanställts och redovisats i grafer. Teorierna testas mot ett korruptionsindex (CPI) och därefter följer en analys av respektive teori. Uppsatsen påvisar att det finns starka samband mellan samtliga teorier och korruptionsindex. Avslutningsvis konstateras att inga nya empiriska slutsatser kan dras, men att de uppmärksammade teoriernas validitet har stärkts. En diskussion om metodologiska överväganden och tillägg inför vidare forskning förs i slutet av uppsatsen

Surgical Aspects of Sleeve Gastrectomy Are Related to Weight Loss and Gastro-esophageal Reflux Symptoms

Introduction A large variation in outcome has been reported after sleeve gastrectomy (SG) across countries and institutions. We aimed to evaluate the effect of surgical technique on total weight loss (TWL) and gastro-esophageal reflux disease (GERD). Methods Observational cohort study based on data from the national registries for bariatric surgery in the Netherlands, Norway, and Sweden. A retrospective analysis of prospectively obtained data from surgeries during 2015–2017 was performed based on 2-year follow-up. GERD was defined as continuous use of acid-reducing medication. The relationship between TWL, de novo GERD and operation technical variables were analyzed with regression methods. Results A total of 5927 patients were included. The average TWL was 25.6% in Sweden, 28.6% in the Netherlands, and 30.6% in Norway (p < 0.001 pairwise). Bougie size, distance from the resection line to the pylorus and the angle of His differed between hospitals. A minimized sleeve increased the expected total weight loss by 5–10 percentage points. Reducing the distance to the angle of His from 3 to just above 0 cm increased the risk of de novo GERD five-fold (from 3.5 to 17.8%). Conclusion Smaller bougie size, a shorter distance to pylorus and to the angle of His were all associated with greater weight loss, whereas a shorter distance to angle of His was associated with more de novo reflux.publishedVersio

Potential effects of bariatric surgery on the incidence of heart failure and atrial fibrillation in patients with type 2 diabetes mellitus and obesity and on mortality in patients with preexisting heart failure: a nationwide, matched, observational cohort study

Background: Obesity and diabetes mellitus are strongly associated with heart failure (HF) and atrial fibrillation (AF). The benefits of bariatric surgery on cardiovascular outcomes are known in people with or without diabetes mellitus. Surgical treatment of obesity might also reduce the incidence of HF and AF in individuals with obesity and type 2 diabetes mellitus (T2DM). Methods and Results: In this register‐based nationwide cohort study we compared individuals with T2DM and obesity who underwent Roux‐en‐Y gastric bypass surgery with matched individuals not treated with surgery. The main outcome measures were hospitalization for HF and/or AF and mortality in patients with preexisting HF. We identified 5321 individuals with T2DM and obesity who had undergone Roux‐en‐Y gastric bypass surgery between January 2007 and December 2013 and 5321 matched controls. The individuals included were 18 to 65 years old and had a body mass index &gt;27.5 kg/m2. The follow‐up time for hospitalization was until the end of 2015 (mean 4.5 years) and the end of 2016 for death. Our results show a 73% lower risk for HF (hazard ratio [HR], 0.27; CI, 0.19–0.38), 41% for AF (HR, 0.59; CI, 0.44–0.78), and 77% for concomitant AF and HF (HR, 0.23; CI, 0.12–0.46) in the surgically treated group. In patients with preexisting HF we observed significantly lower mortality in the group who underwent surgery (HR, 0.23; 95% CI, 0.12–0.43). Conclusions: Bariatric surgery may reduce risk for HF and AF in patients with T2DM and obesity, speculatively via positive cardiovascular and renal effects. Obesity treatment with surgery may also be a valuable alternative in selected patients with T2DM and HF