Finding the Kraus decomposition from a master equation and vice versa

For any master equation which is local in time, whether Markovian, non-Markovian, of Lindblad form or not, a general procedure is reviewed for constructing the corresponding linear map from the initial state to the state at time t, including its Kraus-type representations. Formally, this is equivalent to solving the master equation. For an N-dimensional Hilbert space it requires (i) solving a first order N^2 x N^2 matrix time evolution (to obtain the completely positive map), and (ii) diagonalising a related N^2 x N^2 matrix (to obtain a Kraus-type representation). Conversely, for a given time-dependent linear map, a necessary and sufficient condition is given for the existence of a corresponding master equation, where the (not necessarily unique) form of this equation is explicitly determined. It is shown that a `best possible' master equation may always be defined, for approximating the evolution in the case that no exact master equation exists. Examples involving qubits are given.Comment: 16 pages, no figures. Appeared in special issue for conference QEP-16, Manchester 4-7 Sep 200

Cohort Study of Psychiatric Adverse Events Following Exposure to Levonorgestrel-Containing Intrauterine Devices in UK General Practice

Introduction: Intrauterine devices are implantable contraceptives of which some brands steadily release levonorgestrel over an extended time period. Exposure to a levonorgestrel-releasing intrauterine device has been associated with depression and, more recently, a connection to anxiety, panic attacks, sleep problems and restlessness has been suggested. This study uses data from the THIN database of UK general practice to investigate these suggestions.Methods: A cohort study was performed to compare the incidence of psychiatric adverse events between groups of women who were new users of levonorgestrel-releasing and non-hormonal intrauterine devices. Hazard ratios for the first occurrence of psychiatric symptoms or prescriptions of disease-specific treatments were calculated on an intention-to-treat basis using a proportional hazards model.Results: Significant associations were found between levonorgestrel exposure and records of anxiety (hazard ratio = 1.18; 95% confidence interval 1.08-1.29) and sleep problems (hazard ratio = 1.22; 95% confidence interval 1.08-1.38) in women without a prior record of these events. No significant associations were found for panic attacks or restlessness. Clear baseline differences in clinical characteristics and age between the groups were present. These were included in the model as potential confounding factors.Conclusion: Statistically significant associations of levonorgestrel exposure with anxiety and sleep problems were observed. Substantive differences in baseline characteristics of the treated groups make robust conclusions difficult but the results strongly suggest that additional studies are warranted.</p

A genetic variation map for chicken with 2.8 million single-nucleotide polymorphisms

We describe a genetic variation map for the chicken genome containing 2.8 million single-nucleotide polymorphisms ( SNPs). This map is based on a comparison of the sequences of three domestic chicken breeds ( a broiler, a layer and a Chinese silkie) with that of their wild ancestor, red jungle fowl. Subsequent experiments indicate that at least 90% of the variant sites are true SNPs, and at least 70% are common SNPs that segregate in many domestic breeds. Mean nucleotide diversity is about five SNPs per kilobase for almost every possible comparison between red jungle fowl and domestic lines, between two different domestic lines, and within domestic lines - in contrast to the notion that domestic animals are highly inbred relative to their wild ancestors. In fact, most of the SNPs originated before domestication, and there is little evidence of selective sweeps for adaptive alleles on length scales greater than 100 kilobases

The promises of gravitational-wave astronomy

No abstract available

Hur kommer Sea Traffic Management att påverka kommunikationen i sjöräddning?

Idag är Sea Traffic Management (STM) ett omtalat ämne inom sjöfartsklustret i Europa då dess syfte är att effektivisera både tidsmässigt och miljömässigt och framförallt göra sjöfarten säkrare för alla inblandade. Detta sker genom ett flertal tjänster varav några av dem är funktionella i Search and Rescue (SAR). Syftet med denna studie var att ta reda på hur båtar med olika teknisk prestanda kommunicerar och hur deras situationsuppfattning påverkas i sjöräddningsinsatser när enheterna kommunicerar på olika sätt. Med STM kommer funktioner som chatt, delning av områden och rutter via internet och Automatic Identification System (AIS). Det medför att mycket av den information som idag skickas via radio istället kan skickas direkt till berörd enhet som textmeddelande. Detta undersöktes genom att utföra en sökövning på räddningsstationen Rörö med båtar med olika teknisk prestanda och analysera kommunikationen som skickades. Resultatet visar på tendenser att båtar med förmågan att kommunicera via flera kommunikationsmöjligheter, STM och radio, har en bättre uppfattning av situationen än enheter utan

Hur kommer Sea Traffic Management att påverka kommunikationen i sjöräddning?

Idag är Sea Traffic Management (STM) ett omtalat ämne inom sjöfartsklustret i Europa då dess syfte är att effektivisera både tidsmässigt och miljömässigt och framförallt göra sjöfarten säkrare för alla inblandade. Detta sker genom ett flertal tjänster varav några av dem är funktionella i Search and Rescue (SAR). Syftet med denna studie var att ta reda på hur båtar med olika teknisk prestanda kommunicerar och hur deras situationsuppfattning påverkas i sjöräddningsinsatser när enheterna kommunicerar på olika sätt. Med STM kommer funktioner som chatt, delning av områden och rutter via internet och Automatic Identification System (AIS). Det medför att mycket av den information som idag skickas via radio istället kan skickas direkt till berörd enhet som textmeddelande. Detta undersöktes genom att utföra en sökövning på räddningsstationen Rörö med båtar med olika teknisk prestanda och analysera kommunikationen som skickades. Resultatet visar på tendenser att båtar med förmågan att kommunicera via flera kommunikationsmöjligheter, STM och radio, har en bättre uppfattning av situationen än enheter utan

Dynamics of Antibiotic Resistant Mycobacterium tuberculosis during Long-Term Infection and Antibiotic Treatment

For an infecting bacterium the human body provides several potential ecological niches with both internally (e.g. host immunity) and externally (e.g. antibiotic use) imposed growth restrictions that are expected to drive adaptive evolution in the bacterium, including the development of antibiotic resistance. To determine the extent and pattern of heterogeneity generated in a bacterial population during long-term antibiotic treatment, we examined in a monoclonal Mycobacterium tuberculosis infection antibiotic resistant mutants isolated from one patient during a 9-years period. There was a progressive accumulation of resistance mutations in the infecting clone. Furthermore, apparent clonal sweeps as well as co-existence of different resistant mutants were observed during this time, demonstrating that during treatment there is a high degree of dynamics in the bacterial population. These findings have important implications for diagnostics and treatment of drug resistant tuberculosis infections

Current evidence for a modulation of low back pain by human genetic variants

The manifestation of chronic back pain depends on structural, psychosocial, occupational and genetic influences. Heritability estimates for back pain range from 30% to 45%. Genetic influences are caused by genes affecting intervertebral disc degeneration or the immune response and genes involved in pain perception, signalling and psychological processing. This inter-individual variability which is partly due to genetic differences would require an individualized pain management to prevent the transition from acute to chronic back pain or improve the outcome. The genetic profile may help to define patients at high risk for chronic pain. We summarize genetic factors that (i) impact on intervertebral disc stability, namely Collagen IX, COL9A3, COL11A1, COL11A2, COL1A1, aggrecan (AGAN), cartilage intermediate layer protein, vitamin D receptor, metalloproteinsase-3 (MMP3), MMP9, and thrombospondin-2, (ii) modify inflammation, namely interleukin-1 (IL-1) locus genes and IL-6 and (iii) and pain signalling namely guanine triphosphate (GTP) cyclohydrolase 1, catechol-O-methyltransferase, μ opioid receptor (OPMR1), melanocortin 1 receptor (MC1R), transient receptor potential channel A1 and fatty acid amide hydrolase and analgesic drug metabolism (cytochrome P450 [CYP]2D6, CYP2C9)

The impact of land use/land cover scale on modelling urban ecosystem services

Context Urbanisation places increasing stress on ecosystem services; however existing methods and data for testing relationships between service delivery and urban landscapes remain imprecise and uncertain. Unknown impacts of scale are among several factors that complicate research. This study models ecosystem services in the urban area comprising the towns of Milton Keynes, Bedford and Luton which together represent a wide range of the urban forms present in the UK. Objectives The objectives of this study were to test (1) the sensitivity of ecosystem service model outputs to the spatial resolution of input data, and (2) whether any resultant scale dependency is constant across different ecosystem services and model approaches (e.g. stock- versus flow-based). Methods Carbon storage, sediment erosion, and pollination were modelled with the InVEST framework using input data representative of common coarse (25 m) and fine (5 m) spatial resolutions. Results Fine scale analysis generated higher estimates of total carbon storage (9.32 vs. 7.17 kg m−2) and much lower potential sediment erosion estimates (6.4 vs. 18.1 Mg km−2 year−1) than analyses conducted at coarser resolutions; however coarse-scale analysis estimated more abundant pollination service provision. Conclusions Scale sensitivities depend on the type of service being modelled; stock estimates (e.g. carbon storage) are most sensitive to aggregation across scales, dynamic flow models (e.g. sediment erosion) are most sensitive to spatial resolution, and ecological process models involving both stocks and dynamics (e.g. pollination) are sensitive to both. Care must be taken to select model data appropriate to the scale of inquiry