Recovering hidden Bloch character: Unfolding Electrons, Phonons, and Slabs

For a quantum state, or classical harmonic normal mode, of a system of spatial periodicity "R", Bloch character is encoded in a wavevector "K". One can ask whether this state has partial Bloch character "k" corresponding to a finer scale of periodicity "r". Answering this is called "unfolding." A theorem is proven that yields a mathematically clear prescription for unfolding, by examining translational properties of the state, requiring no "reference states" or basis functions with the finer periodicity (r,k). A question then arises, how should one assign partial Bloch character to a state of a finite system? A slab, finite in one direction, is used as the example. Perpendicular components k_z of the wavevector are not explicitly defined, but may be hidden in the state (and eigenvector |i>.) A prescription for extracting k_z is offered and tested. An idealized silicon (111) surface is used as the example. Slab-unfolding reveals surface-localized states and resonances which were not evident from dispersion curves alone.Comment: 11 pages, 7 figure

Optical signatures of quantum delocalization over extended domains in photosynthetic membranes

The prospect of coherent dynamics and excitonic delocalization across several light-harvesting structures in photosynthetic membranes is of considerable interest, but challenging to explore experimentally. Here we demonstrate theoretically that the excitonic delocalization across extended domains involving several light-harvesting complexes can lead to unambiguous signatures in the optical response, specifically, linear absorption spectra. We characterize, under experimentally established conditions of molecular assembly and protein-induced inhomogeneities, the optical absorption in these arrays from polarized and unpolarized excitation, and demonstrate that it can be used as a diagnostic tool to determine the coherent coupling among iso-energetic light-harvesting structures. The knowledge of these couplings would then provide further insight into the dynamical properties of transfer, such as facilitating the accurate determination of F\"orster rates.Comment: 4 figures and Supplementary information with 7 figures. To appear in Journal of physical chemistry A, 201

Magnetism of two-dimensional defects in Pd: stacking faults, twin boundaries and surfaces

Careful first-principles density functional calculations reveal the importance of hexagonal versus cubic stacking of closed packed planes of Pd as far as local magnetic properties are concerned. We find that, contrary to the stable face centered cubic phase, which is paramagnetic, the hexagonal close-packed phase of Pd is ferromagnetic with a magnetic moment of 0.35 $\mu_{B}$/atom. Our results show that two-dimensional defects with local hcp stacking, like twin boundaries and stacking faults, in the otherwise fcc Pd structure, increase the magnetic susceptibility. The (111) surface also increases the magnetic susceptibility and it becomes ferromagnetic in combination with an individual stacking fault or twin boundary close to it. On the contrary, we find that the (100) surface decreases the tendency to ferromagnetism. The results are consistent with the magnetic moment recently observed in small Pd nanoparticles, with a large surface area and a high concentration of two-dimensional stacking defects.Comment: 8 pages, 10 figure

Evidence-based rules from family practice to inform family practice; The learning healthcare system case study on urinary tract infections

Background: Analysis of encounter data relevant to the diagnostic process sourced from routine electronic medical record (EMR) databases represents a classic example of the concept of a learning healthcare system (LHS). By collecting International Classification of Primary Care (ICPC) coded EMR data as part of the Transition Project from Dutch and Maltese databases (using the EMR TransHIS), data mining algorithms can empirically quantify the relationships of all presenting reasons for encounter (RfEs) and recorded diagnostic outcomes. We have specifically looked at new episodes of care (EoC) for two urinary system infections: simple urinary tract infection (UTI, ICPC code: U71) and pyelonephritis (ICPC code: U70). Methods: Participating family doctors (FDs) recorded details of all their patient contacts in an EoC structure using the ICPC, including RfEs presented by the patient, and the FDs' diagnostic labels. The relationships between RfEs and episode titles were studied using probabilistic and data mining methods as part of the TRANSFoRm project. Results: The Dutch data indicated that the presence of RfE's "Cystitis/Urinary Tract Infection", "Dysuria", "Fear of UTI", "Urinary frequency/urgency", "Haematuria", "Urine symptom/complaint, other" are all strong, reliable, predictors for the diagnosis "Cystitis/Urinary Tract Infection". The Maltese data indicated that the presence of RfE's "Dysuria", "Urinary frequency/urgency", "Haematuria" are all strong, reliable, predictors for the diagnosis "Cystitis/Urinary Tract Infection". The Dutch data indicated that the presence of RfE's "Flank/axilla symptom/complaint", "Dysuria", "Fever", "Cystitis/Urinary Tract Infection", "Abdominal pain/cramps general" are all strong, reliable, predictors for the diagnosis "Pyelonephritis". The Maltese data set did not present any clinically and statistically significant predictors for pyelonephritis. Conclusions: We describe clinically and statistically significant diagnostic associations observed between UTIs and pyelonephritis presenting as a new problem in family practice, and all associated RfEs, and demonstrate that the significant diagnostic cues obtained are consistent with the literature. We conclude that it is possible to generate clinically meaningful diagnostic evidence from electronic sources of patient data

The nature of the low energy band of the Fenna-Matthews-Olson complex: vibronic signatures

Based entirely upon actual experimental observations on electron-phonon coupling, we develop a theoretical framework to show that the lowest energy band of the Fenna- Matthews-Olson (FMO) complex exhibits observable features due to the quantum nature of the vibrational manifolds present in its chromophores. The study of linear spectra provides us with the basis to understand the dynamical features arising from the vibronic structure in non-linear spectra in a progressive fashion, starting from a microscopic model to finally performing an inhomogenous average. We show that the discreteness of the vibronic structure can be witnessed by probing the diagonal peaks of the non-linear spectra by means of a relative phase shift in the waiting time resolved signal. Moreover, we demonstrate the photon-echo and non-rephasing paths are sensitive to different harmonics in the vibrational manifold when static disorder is taken into account. Supported by analytical and numerical calculations, we show that nondiagonal resonances in the 2D spectra in the waiting time, further capture the discreteness of vibrations through a modulation of the amplitude without any effect in the signal intrinsic frequency. This fact generates a signal that is highly sensitive to correlations in the static disorder of the excitonic energy albeit protected against dephasing due to inhomogeneities of the vibrational ensemble.Comment: 14 pages, 6 figure

The concept of control in chronic obstructive pulmonary disease: Development of the criteria and validation for use in clinical practice

Guidelines of treatment of chronic obstructive pulmonary disease (COPD) identify symptom reduction and prevention of exacerbations as the main goals of therapy. Initial pharmacological treatment must be guided by these parameters, and effectiveness must be assessed at each clinical visit. However, there is no clear guidance as to how this assessment must be performed. The concept of control has been well developed in asthma, but it has been elusive in COPD. Patients with COPD may not be completely free from symptoms or exacerbations even under optimized therapy; therefore, control in COPD does not mean cure or absence of symptoms, but rather reaching the best clinical status possible according to the level of disease severity. A control tool has been developed based on a cross sectional evaluation of the impact of the disease and a longitudinal evaluation of stability. Low impact is a disease status defined by at least 3 of the following: low levels of dyspnoea, absence of or white sputum, low use of rescue medication and self-declared walking time of more than 30 minutes a day, and stability is the absence of moderate or severe exacerbations in the previous 3 months. Control can also be defined by COPD Assessment Test (CAT) scores ≤ 10 units for patients with FEV1 ≥ 50% and 16 for patients with FEV1 < 50% and stability as a change in CAT ≤ 2 units. Control of COPD is then defined as a status of low impact and stability. The control tool has been validated prospectively in several studies and has demonstrated to be sensitive to clinical changes and to have a good predictive value for poor outcomes. Clinical criteria are more reliable than CAT scores for the evaluation of control. The control tool is a quick and inexpensive method to evaluate clinical status and future risk of exacerbations that can be used at all levels of healthcare. Концепция контроля при лечении хронической обструктивной болезни легких: разработка критериев и валидация для клинического применения (перевод с английского)По данным рекомендаций, при лечении хронической обструктивной болезни легких (ХОБЛ) в качестве главных целей лечения выделяются купирование симптомов и предотвращение обострений. При первоначальной медикаментозной терапии следует руководствоваться именно этими параметрами, а эффективность должна оцениваться при каждом посещении пациентом врача. Однако четких рекомендаций о том, как именно проводить такую оценку, не существует. Концепция контроля хорошо разработана при лечении бронхиальной астмы, однако для ХОБЛ сформулировать таковую оказалось намного труднее. Пациенты с ХОБЛ могут продолжать испытывать симптомы болезни, даже получая оптимальную терапию; таким образом, контроль над ХОБЛ означает не полное излечение или отсутствие симптомов, а достижение наилучшего возможного клинического статуса при данной степени тяжести заболевания. Авторами данной статьи разработан инструмент для определения контроля над ХОБЛ на основе поперечного среза данных о нагрузке на здоровье пациента и лонгитюдинальной оценки стабильности его состояния. Низкая нагрузка определяется как удовлетворяющая минимум 3 критериям из следующих: низкий уровень одышки; отсутствие мокроты или белая мокрота; малое использование симптоматической терапии; 30 мин ходьбы пешком в день согласно самооценке. Стабильность определяется как отсутствие умеренно тяжелых или тяжелых обострений в предшествующие 3 мес. Контроль также осуществляется по результатам теста по оценке степени тяжести ХОБЛ (COPD Assesment Test – CAT) следующим образом: ≤ 10 единиц – для пациентов, у которых показатель объема форсированного выдоха за 1-ю секунду (ОФВ1) составляет ≥ 50 %; ≤ 16 – при ОФВ1 < 50 %; стабильность определяется как изменение оценки по CAT ≤ 2 единиц. Таким образом, контроль над ХОБЛ определяется как состояние стабильно низкой нагрузки на здоровье. Инструмент для определения контроля валидирован проспективно по данным ряда исследований, при этом продемонстрированы чувствительность к изменениям клинического состояния пациентов и бόльшая прогностическая ценность по отношению к негативным исходам. Кли - нические критерии оказались надежнее в определении статуса контроля, чем баллы по CAT. Таким образом, концепция контроля – это быстрый и недорогой метод оценки клинического статуса и риска обострений в будущем, который пригоден к использованию на всех уровнях здравоохранения

An Imprint of Molecular Cloud Magnetization in the Morphology of the Dust Polarized Emission

We describe a morphological imprint of magnetization found when considering the relative orientation of the magnetic field direction with respect to the density structures in simulated turbulent molecular clouds. This imprint was found using the Histogram of Relative Orientations (HRO): a new technique that utilizes the gradient to characterize the directionality of density and column density structures on multiple scales. We present results of the HRO analysis in three models of molecular clouds in which the initial magnetic field strength is varied, but an identical initial turbulent velocity field is introduced, which subsequently decays. The HRO analysis was applied to the simulated data cubes and mock-observations of the simulations produced by integrating the data cube along particular lines of sight. In the 3D analysis we describe the relative orientation of the magnetic field $\mathbf{B}$ with respect to the density structures, showing that: 1.The magnetic field shows a preferential orientation parallel to most of the density structures in the three simulated cubes. 2.The relative orientation changes from parallel to perpendicular in regions with density over a critical density $n_{T}$ in the highest magnetization case. 3.The change of relative orientation is largest for the highest magnetization and decreases in lower magnetization cases. This change in the relative orientation is also present in the projected maps. In conjunction with simulations HROs can be used to establish a link between the observed morphology in polarization maps and the physics included in simulations of molecular clouds.Comment: (16 pages, 11 figures, submitted to ApJ 05MAR2013, accepted 07JUL2013