Search

We report on magnetic resonance force microscopy measurements of the Boltzmann polarization of nuclear spins in copper by detecting the frequency shift of a soft cantilever. We use the time-dependent solution of the Bloch equations to derive a concise equation describing the effect of radio-frequent (RF) magnetic fields on both on- and off-resonant spins in high magnetic field gradients. We then apply this theory to saturation experiments performed on a 100 nm thick layer of copper, where we use the higher modes of the cantilever as a source of the RF field. We demonstrate a detection volume sensitivity of only (40 nm) 3 , corresponding to about 1.6 × 10 4 polarized copper nuclear spins. We propose an experiment on protons where, with the appropriate technical improvements, frequency-shift based magnetic resonance imaging with a resolution better than (10 nm) 3 could be possible. Achieving this resolution would make imaging based on the Boltzmann polarization competitive with the more traditional stochastic spin-fluctuation based imaging, with the possibility to work at millikelvin temperatures. [ABSTRACT FROM AUTHOR]

Pesquisas recentes têm apontado para os LEDs como a tecnologia mais eficiente e durável a ser utilizada em iluminação, no entanto, estes requerem um conversor com a finalidade de controlar a corrente elétrica que flui através da lâmpada a LED. Neste contexto, este trabalho apresenta a análise, projeto e implementação de um conversor com ampla faixa de tensão de entrada chamado Boost-Buck Quadrático. Este utiliza um único interruptor e uma estratégia de controle de simples implementação, e foi projetado para acionar uma lâmpada a LED de 12 W utilizada tanto em sistemas de iluminação de emergência, como iluminação convencional. A principal característica deste sistema é o fato de poder ser alimentado tanto por uma bateria (12 VCC) quanto pela rede CA convencional (90 a 240 Vrms). Para comprovação dos resultados teóricos, são apresentados os resultados experimentais obtidos através de um protótipo construído em laboratório.

Healthcare professionals have to give substance to the role of a champion in order to successfully lead quality improvement (QI) initiatives. This study aims to unravel how hospitalists in training shape their role as a champion within the context of QI projects in hospital care and why some are more effective in leading a QI project than others. We focus on the role of credibility, as it is a prerequisite for fulfilling the role of champion. This multiple-case study builds upon 23 semi-structured interviews with hospitalists in training: quality officers and medical specialists. We first coded data for each case and then described the different contexts of each case in detail to enable comparison across settings. We then compared the cases and contrasted the attributes of credibility. Four attributes of credibility emerged and were identified as essential for the hospitalist in training to succeed as a champion: (1) being convincing about the need for change by providing supportive clinical evidence, (2) displaying competence in their clinical work and commitment to their tasks, (3) generating shared ownership of the QI project with other healthcare professionals, and (4) acting as a team player to foster collaboration during the QI project. We also identified two contextual factors that supported the credibility of the hospitalist in training: (1) choosing a subject for the QI project that was perceived as urgently required by the group of stakeholders involved, and (2) being supported by the board of directors and other formal and informal leaders as the leader of a QI project. Further research is needed to gain a deeper understanding of the relationship between credibility and sustainability of change.

Preclinical data suggest that neoadjuvant chemotherapy (NAT) may promote micrometastatic spread. We aimed to compare the detection rate and prognostic relevance of disseminated tumor cells (DTCs) from the bone marrow (BM) of patients with early-stage breast cancer (EBC) after NAT with that of therapy-naive EBC patients. DTCs were identified from BM samples, collected during primary surgery. Patients who received NAT were compared to patients who received chemotherapy after surgery. In total, 809 patients were analyzed. After NAT, 45.4% of patients were DTC-positive as compared to 19.9% of patients in the adjuvant chemotherapy group ( p < 0.001). When sampled in patients who had undergone NAT, the detection of DTCs in the BM was significantly increased (OR: 3.1; 95% confidence interval (CI): 2.1-4.4; p < 0.001). After NAT, DTC-positive patients with ≥2 DTCs per 1.5 × 10 6 mononuclear cells in their BM had an impaired disease-free survival (HR: 4.8, 95% CI: 0.9-26.6; p = 0.050) and overall survival (HR: 4.2; 95% CI: 1.4-12.7; p = 0.005). The higher rate of DTC-positive patients after NAT as compared to a treatment-naive comparable control cohort suggests that NAT supports tumor cell dissemination into the bone marrow. DTC positivity in BM predicted relapse in various distant organs, implying that tumor cell dissemination was not restricted to the bone marrow.

Background: Several types of audits have been used to promote quality improvement (QI) in hospital care. However, in-depth studies into the mechanisms responsible for the effectiveness of audits in a given context is scarce. We sought to understand the mechanisms and contextual factors that determine why audits might, or might not, lead to improved quality of hospital care., Methods: A realist review was conducted to systematically search and synthesise the literature on audits. Data from individual papers were synthesised by coding, iteratively testing and supplementing initial programme theories, and refining these theories into a set of context-mechanism-outcome configurations (CMOcs)., Results: From our synthesis of 85 papers, seven CMOcs were identified that explain how audits work: (1) externally initiated audits create QI awareness although their impact on improvement diminishes over time; (2) a sense of urgency felt by healthcare professionals triggers engagement with an audit; (3) champions are vital for an audit to be perceived by healthcare professionals as worth the effort; (4) bottom-up initiated audits are more likely to bring about sustained change; (5) knowledge-sharing within externally mandated audits triggers participation by healthcare professionals; (6) audit data support healthcare professionals in raising issues in their dialogues with those in leadership positions; and (7) audits legitimise the provision of feedback to colleagues, which flattens the perceived hierarchy and encourages constructive collaboration., Conclusions: This realist review has identified seven CMOcs that should be taken into account when seeking to optimise the design and usage of audits. These CMOcs can provide policy makers and practice leaders with an adequate conceptual grounding to design contextually sensitive audits in diverse settings and advance the audit research agenda for various contexts., Prospero Registration: CRD42016039882., Competing Interests: The authors have declared that no competing interests exist.

We present the design and implementation of a mechanical low-pass filter vibration isolation used to reduce the vibrational noise in a cryogen-free dilution refrigerator operated at 10 mK, intended for scanning probe techniques. We discuss the design guidelines necessary to meet the competing requirements of having a low mechanical stiffness in combination with a high thermal conductance. We demonstrate the effectiveness of our approach by measuring the vibrational noise levels of an ultrasoft mechanical resonator positioned above a superconducting quantum interference device. Starting from a cryostat base temperature of 8 mK, the vibration isolation can be cooled to 10.5 mK, with a cooling power of 113 µW at 100 mK. We use the low vibrations and low temperature to demonstrate an effective cantilever temperature of less than 20 mK. This results in a force sensitivity of less than 500 zN/Hz and an integrated frequency noise as low as 0.4 mHz in a 1 Hz measurement bandwidth.

Introduction: Many types of audits are commonly used in hospital care to promote quality improvements. However, the evidence on the effectiveness of audits is mixed. The objectives of this proposed realist review are (1) to understand how and why audits might, or might not, work in terms of delivering the intended outcome of improved quality of hospital care and (2) to examine under what circumstances audits could potentially be effective. This protocol will provide the rationale for using a realist review approach and outline the method., Methods and Analysis: This review will be conducted using an iterative four-stage approach. The first and second steps have already been executed. The first step was to develop an initial programme theory based on the literature that explains how audits are supposed to work. Second, a systematic literature search was conducted using relevant databases. Third, data will be extracted and coded for concepts relating to context, outcomes and their interrelatedness. Finally, the data will be synthesised in a five-step process: (1) organising the extracted data into evidence tables, (2) theming, (3) formulating chains of inference from the identified themes, (4) linking the chains of inference and formulating CMO configurations and (5) refining the initial programme theory. The reporting of the review will follow the 'Realist and Meta-Review Evidence Synthesis: Evolving Standards' (RAMESES) publication standards., Ethics and Dissemination: This review does not require formal ethical approval. A better understanding of how and why these audits work, and how context impacts their effectiveness, will inform stakeholders in deciding how to tailor and implement audits within their local context. We will use a range of dissemination strategies to ensure that findings from this realist review are broadly disseminated to academic and non-academic audiences., Prospero Registration Number: CRD42016039882., Competing Interests: Competing interests: None declared., (© Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2017. All rights reserved. No commercial use is permitted unless otherwise expressly granted.)

Using a laser trap, we have studied the properties of erythrocytes from a sickle cell anemia patient (SCA) after receiving an intravenous blood transfusion, and a normal adult individual carrying normal adult hemoglobin. The hemoglobin type and quantitation assessment was carried out by high performance liquid chromatography (HPLC). We conducted an analysis of the size distributions of the cells. By targeting those erythrocytes in the overlapping regions of size distributions, we have investigated their properties when the cells are trapped and released. The efficacy of the transfusion treatment is also studied by comparing the relative changes in deformation and the relaxation-time of the cells in the two samples.

T cells and T cells subsets in peripheral blood of patients with different forms of pulmonary tuberculosis were evaluated to explain some aspects of the immunocompromised state of these subjects. Diagnosis was made by baciloscopy (BAAR), chest roentgenography i.d.r. Mantoux, and other clinical analysis. Spontaneous E-Rosette test (RE) was used to quantify Total (RET 4 degrees C) and Active T cells (REA 37 degrees C) and the same test after incubation with Theophylline (The) for helper cells (The-resistant cells: RETR) and suppressor cells (The-sensitive cells: RETS). Patients were followed for at least 4 months after therapy. The data demonstrate a significant decrease of relative and absolute numbers of Total T-cells and a diminished T helper/T suppressor subset ratio (RETR/RETS) which dropped to less than 1 in untreated patients. Treated patients with a favourable evolution showed a restoration of Total active and helper T cells. RETR/RETS ratio was also significantly increased. In patients with highly positive BAAR, low on negative i.d.r. Mantoux, a decreased level of immunocompetent cells was observed. The 3 aspects were associated. Nutritional condition of the patients was also associated with the predisposition to acquire this disease.