Markovian master equations for quantum thermal machines: local vs global approach

The study of quantum thermal machines, and more generally of open quantum systems, often relies on master equations. Two approaches are mainly followed. On the one hand, there is the widely used, but often criticized, local approach, where machine sub-systems locally couple to thermal baths. On the other hand, in the more established global approach, thermal baths couple to global degrees of freedom of the machine. There has been debate as to which of these two conceptually different approaches should be used in situations out of thermal equilibrium. Here we compare the local and global approaches against an exact solution for a particular class of thermal machines. We consider thermodynamically relevant observables, such as heat currents, as well as the quantum state of the machine. Our results show that the use of a local master equation is generally well justified. In particular, for weak inter-system coupling, the local approach agrees with the exact solution, whereas the global approach fails for non-equilibrium situations. For intermediate coupling, the local and the global approach both agree with the exact solution and for strong coupling, the global approach is preferable. These results are backed by detailed derivations of the regimes of validity for the respective approaches.Comment: Published version. See also the related work by J. Onam Gonzalez et al. arXiv:1707.0922

Markovian master equations for quantum thermal machines: local versus global approach

The study of quantum thermal machines, and more generally of open quantum systems, often relies on master equations. Two approaches are mainly followed. On the one hand, there is the widely used, but often criticized, local approach, where machine sub-systems locally couple to thermal baths. On the other hand, in the more established global approach, thermal baths couple to global degrees of freedom of the machine. There has been debate as to which of these two conceptually different approaches should be used in situations out of thermal equilibrium. Here we compare the local and global approaches against an exact solution for a particular class of thermal machines. We consider thermodynamically relevant observables, such as heat currents, as well as the quantum state of the machine. Our results show that the use of a local master equation is generally well justified. In particular, for weak inter-system coupling, the local approach agrees with the exact solution, whereas the global approach fails for non-equilibrium situations. For intermediate coupling, the local and the global approach both agree with the exact solution and for strong coupling, the global approach is preferable. These results are backed by detailed derivations of the regimes of validity for the respective approaches

An antibody that prevents serpin polymerisation acts by inducing a novel allosteric behavior

Serpins are important regulators of proteolytic pathways with an antiprotease activity that involves a conformational transition from a metastable to a hyperstable state. Certain mutations permit the transition to occur in the absence of a protease; when associated with an intermolecular interaction, this yields linear polymers of hyperstable serpin molecules, which accumulate at the site of synthesis. This is the basis of many pathologies termed the serpinopathies. We have previously identified a monoclonal antibody (mAb4B12) that, in single-chain form, blocks α1-Antitrypsin (α1-AT) polymerisation in cells. Here, we describe the structural basis for this activity. The mAb4B12 epitope was found to encompass residues Glu32, Glu39 and His43 on helix A and Leu306 on helix I. This is not a region typically associated with the serpin mechanism of conformational change, and correspondingly the epitope was present in all tested structural forms of the protein. Antibody binding rendered β-sheet A - on the opposite face of the molecule - more liable to adopt an 'open' state, mediated by changes distal to the breach region and proximal to helix F. The allosteric propagation of induced changes through the molecule was evidenced by an increased rate of peptide incorporation and destabilisation of a preformed serpin-enzyme complex following mAb4B12 binding. These data suggest that prematurely shifting the β-sheet A equilibrium towards the 'open' state out of sequence with other changes suppresses polymer formation. This work identifies a region potentially exploitable for a rational design of ligands that is able to dynamically influence α1-AT polymerisation

Small X-Band Oscillator Antennas

A small, segmented microstrip patch antenna integrated with an X-band feedback oscillator on a high-permittivity substrate has been built and tested. This oscillator antenna is a prototype for demonstrating the feasibility of such devices as compact, low-power-consumption building blocks of advanced, lightweight, phased antenna arrays that would generate steerable beams for communication and remotesensing applications

The BHLF1 locus of Epstein-Barr virus contributes to viral latency and B-cell immortalization

Funding: U.S. Public Health Service grant AI110328 to J.T.S. and in part by Commonwealth Universal Research Enhancement (CURE) funds. L.N.L. received support from National Cancer Institute training grant T32 CA060395, and is a Lymphoma Research Foundation Grantee.The Epstein-Barr virus (EBV) BHLF1 gene encodes an abundant linear and several circular RNAs believed to perform non-coding functions during virus replication, though an open reading frame is retained among an unknown percentage of EBV isolates. Evidence suggests that BHLF1 is also transcribed during latent infection, which prompted us to investigate the contribution of this locus to latency. Analysis of transcripts transiting BHLF1 revealed its transcription is widespread among B-cell lines supporting the latency I or III program of EBV protein expression, and to be more complex than originally presumed. EBV-negative Burkitt lymphoma cell lines infected with either wild-type or two different BHLF1 mutant EBVs were initially indistinguishable in supporting latency III. However, cells infected with BHLF1- virus ultimately transitioned to the more restrictive latency I, whereas cells infected with wild-type virus either sustained latency III or transitioned more slowly to latency I. Upon infection of primary B cells, which require latency III for growth in vitro, both BHLF1- viruses exhibited variably reduced immortalization potential relative to wild-type virus. Finally, in transfection experiments, efficient protein expression from an intact BHLF1 ORF required the EBV post-transcriptional regulator protein SM, whose expression is limited to the replicative cycle. Thus, one way in which BHLF1 may contribute to latency is through a mechanism, possibly mediated or regulated by a long non-coding RNA, that supports latency III critical for the establishment of EBV latency and lifelong persistence within its host, whereas any retained protein-dependent function of BHLF1 may be restricted to the replication cycle. Importance. Epstein-Barr virus (EBV) has significant oncogenic potential that is linked to its latent infection of B lymphocytes, during which virus replication is not supported. Establishment of latent infection, which is life long and can precede tumor development by years, requires the concerted actions of nearly a dozen EBV proteins and numerous small non-protein-coding RNAs. Elucidation of how these EBV products contribute to latency is crucial to understanding EBV's role in specific malignancies, and ultimately to clinical intervention. Historically, EBV genes that contribute to virus replication have been excluded from consideration of a role in latency, primarily because of the general incompatibility between virus production and cell survival. However, here we provide evidence that the genetic locus containing one such gene, BHLF1, indeed contributes to key aspects of EBV latency, including its ability to promote continuous growth of B lymphocytes, thus providing significant new insight into EBV biology and oncogenic potential.PostprintPeer reviewe

Corrente do Brasil: estrutura térmica entre 19º e 25ºS e circulação geostrófica

In April 1982, an océanographie investigation was conducted off the Brazilian coast in order to obtain the spatial characteristics of the thermal structure and to locate the Brazil Current flow both north and south of the seamount chain at 20º30'S. Dining the survey, remote sensing satellite data were also obtained on several occasions to assist in the delineation of the surface thermal structure. A 23ºC thermostad was observed along most sections. Along sections with stronger baroclinic signatures, such as the one in Cabo Frio, the thermostad seems to be pinched off somewhat similar to the pinching off the 18ºC water in the Gulf Stream North wall. The current structure and volume transports, relative to the 500 dbar isobaric surface, were calculated using both hydrographie station data and the closely spaced XBT measurements. A comparison of these results, for the data observed along the section of Cabo Frio, indicates that some details of the geostrophic currents are lost when the hydrographie data are used; the corresponding volume transports agree within 17% (33 Sv using hydrographie data against 2.8 Sv using XBT data). A volume transport budget, obtained through the transport computation along all sections between 19º and 22ºS, indicates that the Brazil Current appears to flow through the passage between the most inshore banks and not to the east. The net volume transport (2.9 Sv) is in close agreement with the Cabo Frio section volume transport, where the total flow of the Brazil Current was supposedly bracketed by the station sampling.Para obter informações sobre a variação espacial da estrutura térmica e localizar a Corrente do Brasil, ao norte e ao sul dos bancos submarinos localizados a 20º30'S realizou-se, em abril de 1982, um levantamento oceanográfico nessa região. Dados de sensoriamento remoto foram também obtidos durante os trabalhos experimentais para um delineamento sinótico da estrutura térmica de superficie. Observou-se, ao longo da maioria das secções, um "thermostad" de 23ºC na termoclina principal. Ao longo das secções com intenso sinal baroclfnico, tal como na secção ao largo de Cabo Frio, o "thermostad" atenua-se e finalmente desaparece nas proximidades da costa, de forma semelhante ao desaparecimento da água de 18ºC na parede norte da Corrente do Golfo. A estrutura da corrente e o transporte de volume, relativos à superfície isobárica de 500 dbar, foram obtidos usando-se os dados hidrográficos e também as medidas com XBX as quais foram realizadas com espaçamentos muito menores do que o das estações hidrográficas. A comparação desses resultados, para o conjunto de observações conduzidas ao largo de Cabo Frio, indica que detalhes da corrente geostrófica não são delineados quando da utilização dos dados hidrográficos; os correspondentes valores do transporte de volume diferem em aproximadamente 17% (33 e 2,8 Sv, calculados com dados hidrográficos'e de XBX respectivamente). O balanço do transporte de volume, através de todas as secções entre 19 e 22º5, indica que a Corrente do Brasil flui através da passagem entre os bancos localizados mais próximos da costa. O transporte de volume resultante (2,9 Sv) é muito próximo do valor obtido através da secção ao largo de Cabo Frio, onde supõe-se que a extensão transversal da Corrente do Brasil foi delimitada pelo conjunto de observações

Economics methods in Cochrane systematic reviews of health promotion and public health related interventions.

Peer reviewedPublisher PD

Non-Perturbative Topological Strings And Conformal Blocks

We give a non-perturbative completion of a class of closed topological string theories in terms of building blocks of dual open strings. In the specific case where the open string is given by a matrix model these blocks correspond to a choice of integration contour. We then apply this definition to the AGT setup where the dual matrix model has logarithmic potential and is conjecturally equivalent to Liouville conformal field theory. By studying the natural contours of these matrix integrals and their monodromy properties, we propose a precise map between topological string blocks and Liouville conformal blocks. Remarkably, this description makes use of the light-cone diagrams of closed string field theory, where the critical points of the matrix potential correspond to string interaction points.Comment: 36 page

Long term cause specific mortality among 34 489 five year survivors of childhood cancer in Great Britain:population based cohort study

Objective To determine whether modern treatments for cancer are associated with a net increased or decreased risk of death from neoplastic and non-neoplastic causes among survivors of childhood cancer. Design Population based cohort study. Setting British Childhood Cancer Survivor Study. Participants Nationwide population based cohort of 34 489 five year survivors of childhood cancer with a diagnosis from 1940 to 2006 and followed up until 28 February 2014. Main outcome measures Cause specific standardised mortality ratios and absolute excess risks are reported. Multivariable Poisson regression models were utilised to evaluate the simultaneous effect of risk factors. Likelihood ratio tests were used to test for heterogeneity or trend. Results Overall, 4475 deaths were observed, which was 9.1 (95% confidence interval 8.9 to 9.4) times that expected in the general population, corresponding to 64.2 (95% confidence interval 62.1 to 66.3) excess deaths per 10 000 person years. The number of excess deaths from all causes declined among those treated more recently; those treated during 1990-2006 experienced 30% of the excess number of deaths experienced by those treated before 1970. The corresponding percentages for the decline in excess deaths from recurrence or progression and non-neoplastic causes were 30% and 60%, respectively. Among survivors aged 50-59 years, 41% and 22% of excess deaths were attributable to subsequent primary neoplasms and circulatory conditions, respectively, whereas the corresponding percentages among those aged 60 years or more were 31% and 37%. Conclusions The net effects of changes in cancer treatments, and surveillance and management for late effects, over the period 1940 to 2006 was to reduce the excess number of deaths from both recurrence or progression and non-neoplastic causes among those treated more recently. Among survivors aged 60 years or more, the excess number of deaths from circulatory causes exceeds the excess number of deaths from subsequent primary neoplasms. The important message for the evidence based surveillance aimed at preventing excess mortality and morbidity in survivors aged 60 years or more is that circulatory disease overtakes subsequent primary neoplasms as the leading cause of excess mortality