Optical absorption in small BN and C nanotubes

We present a theoretical study of the optical absorption spectrum of small boron-nitride and carbon nanotubes using time-dependent density-functional theory and the random phase approximation. Both for C and BN tubes, the absorption of light polarized perpendicular to the tube-axis is strongly suppressed due to local field effects. Since BN-tubes are wide band-gap insulators, they only absorb in the ultra-violet energy regime, independently of chirality and diameter. In comparison with the spectra of the single C and BN-sheets, the tubes display additional fine-structure which stems from the (quasi-) one-dimensionality of the tubes and sensitively depends on the chirality and tube diameter. This fine structure can provide additional information for the assignment of tube indices in high resolution optical absorption spectroscopy.Comment: 5 pages, 3 figure

Medicine without borders: a literature review of short-term international medical missions

AbstractBackgroundEach year, medical providers and trainees travel to low-income and middle-income countries to deliver direct medical care via short-term medical missions (STMMs) lasting between 1 day and 2 years. In spite of the high prevalence of STMMs, little aggregate information exists about where STMMs go, the services they deliver, and their relationship to the recipient country's health-care system. Our objective was to review the literature on STMMs to better understand their characteristics and identify how they link to the in-country health system.MethodsWe searched MEDLINE-indexed articles on STMMs published between January, 2010, and August, 2014. Exclusion criteria included publications with exclusive focus on medical school curricula, commentaries, and publications on military or disaster medicine. Of 1538 identified articles, 152 met our criteria. Data extracted from the full text of the eligible articles included article type, subject, and STMM details such as location and duration.FindingsNearly half of all articles (72 [47%]) described one or more specific STMMs without any evaluation of the STMM's work; 48 (32%) broadly discussed the concept of STMMs (eg, ethics, best practices); and 32 (21%) evaluated some aspect of an STMM, such as cost-effectiveness or post-operative complication rates. Most articles focused on the implementation of STMMs (66 [43%]), personal experiences of STMMs (36 [24%]), or ethical issues (23 [15%]). Data from 102 articles that detailed an STMM reveal that most medical teams came from the USA, and most STMMs went to Latin America (42 [42%]) or sub-Saharan Africa (34 [34%]). About 40% of articles (41) explicitly state that students were involved in the STMM. About a third (36 [35%]) of these articles did not specify how long the STMM lasted, and approximately half (53[52%]) did not specify how many people were involved in the STMM. Most publications also lacked essential details about STMMs' link to the destination countries' existing health systems. There was little description of the local health needs or how the STMM would affect local health-care delivery, either favourably or unfavourably.InterpretationPublished articles suggest that the prevalence of international STMMs is on the rise. However, very few publications include rigorous evaluation of the services rendered or describe how STMMs link to the recipient country's health-care system.FundingNone

Numerical and experimental investigation of mixing in a continuously operated fluidized bed

Many processes require solid material to be fed continuously into a fluidized bed. In order to study the related mixing process of the solid feed with the bed material, a laboratory scale experiment with a continuous supply system is set up and monitored with a high resolution camera system. Additionally, two simulation methods are used: The EulerEuler and an Euler-Lagrange approach based on the Discrete-Element-Method (DEM) coupled with CFD. Experimental investigations carried out at varying fluid velocities are compared with simulations. A reasonable agreement is found between the coupled DEMCFD-method and the experimental findings

Radiation heat transfer within the screte element method - relevance, implementation and examples -

Current developments in the energy sector increasingly demand the consideration of fuels with much larger particle sizes, either from alternative sources or due to a reduced pre-processing effort. In numerical simulations of such systems the particles can no longer be considered as non-colliding material points. Municipal waste incineration on grates or wood pellet combustion in domestic boilers are such examples, where the Discrete Element Method (DEM) can be applied to extend the Lagrange tracking of moving particles to a mechanically and thermally fully interacting flow of reacting granular material. In some situations where sufficiently large time scale differences between the processes in the gas phase and in the solid phase exist, distinctive interfaces can be identified between domains, thus allowing a different modelling in these regions. The treatment of the radiative heat transfer between such domains poses particular difficulties at the interfaces. Based on the two exemplary applications mentioned, details of the modelling approach are discussed and corresponding results presented

What drives the active involvement in business angel groups? The role of angels' decision-making style, investment-specific human capital and motivations

This paper sheds light over the operations and internal structure of business angel groups (BAGs), a leading actor inside the informal venture capital industry, due to its capability to build cognitive resources and shared competencies that are eventually provided to funded ventures alongside equity capital. We develop a framework based on the role of business angels' decision-making style, human capital and motivation as major determinants of their active involvement in the many different activities performed by angel groups, either investment related activities or group management activities. Our empirical analysis relies on a novel survey-based dataset containing qualitative and quantitative information provided by the members of two large and rather homogeneous business angel groups located in France and in Italy. Results show that business angels with a control-oriented decision-making style tend to be more actively involved in key angel group activities. Human capital built through investment experience, retirement status, as well as initial motivation to join an angel group are also significant drivers of angel involvement in several key BAG activities

Expression des "activated leukocyte cell adhesion molecule" im Mammakarzinom: Prädiktivität für das Ansprechen auf eine taxanfreie Chemotherapie

Zusammenfassung: Ziele: "Activated leukocyte cell adhesion molecule" (ALCAM) ist ein Oberflächenimmunglobulin und wird in vielen Mammakarzinomen exprimiert. Es wird vermutet, dass ALCAM in der Tumorgenese und -progression eine Rolle spielt. Die Bedeutung des Adhäsionsmoleküls ALCAM für das Ansprechen auf eine taxanfreie adjuvante Chemotherapie wurde untersucht. Material und Methoden: Gewebeproben von 162Patientinnen mit Mammakarzinomen wurden im Hinblick auf die Expression des ALCAM-Proteins untersucht. Immunhistologische Untersuchungen (IHC) und Western-Blot-Analysen (WB) wurden mit einem monoklonalen Antikörper gegen ALCAM durchgeführt. Die Proteinmengen im WB wurden densitometrisch quantifiziert und mit klinischen sowie histologischen Parametern korreliert. Die Ergebnisse wurden auf mRNA-Ebene mithilfe der Microarray-Analysen (Affymetrix) validiert. Ergebnisse: In der normalen Brustdrüse wird ALCAM in den luminalen und den basalen Epithelzellen exprimiert. Die WB-Analysen von Mammakarzinomen zeigen eine positive Korrelation der ALCAM-Expression mit dem Östrogenrezeptorstatus (p=0,04). Bei Patientinnen, die eine taxanfreie Chemotherapie erhalten haben, ist eine hohe ALCAM-Expression (WB, Affymetrix) prädikitiv für das Ansprechen einer Chemotherapie. Der mediane mRNA-Level von ALCAM war bei Patientinnen, die während des Beobachtungszeitraums noch lebten, 4,5-fach höher als bei Patientinnen, die verstarben. Schlussfolgerung: Ein hoher ALCAM-Gehalt korreliert positiv mit dem Östrogenrezeptorstatus. Außerdem ist ALCAM ein prädiktiver Faktor für das Ansprechen einer taxanfreien Chemotherapi

Intrinsic control of interlayer exciton generation rate in van der Waals materials via Janus layers

We demonstrate the possibility of engineering the optical properties of transition metal dichalcogenide heterobilayers when one of the constitutive layers has a Janus structure. This has important consequences for the charge separation efficiency. We investigate different MoS$_2$@Janus layer combinations using first-principles methods including electron-hole interactions (excitons) and exciton-phonon coupling. The direction of the intrinsic electric field from the Janus layer modifies the electronic band alignments and, consequently, the energy separation between interlayer exciton states -- which usually have a very low oscillator strength and hence are almost dark in absorption -- and bright in-plane excitons. We find that in-plane lattice vibrations strongly couple the two states, so that exciton-phonon scattering may be a viable generation mechanism for interlayer excitons upon light absorption. In particular, in the case of MoS$_2$@WSSe, the energy separation of the low-lying interlayer exciton from the in-plane exciton is resonant with the transverse optical phonon modes (40 meV). We thus identify this heterobilayer as a prime candidate for efficient electron-hole pair generation with efficient charge carrier separation

Prevalence and treatment of hypertension, diabetes and asthma in Kenya: A representative household survey in eight counties in 2016

Objectives: In 2014, 27% of total deaths in Kenya were due to non-communicable diseases (NCDs). The objectives of this study were: 1) To report on the prevalence of households with members diagnosed and treated for hypertension, diabetes, and asthma in eight counties in Kenya, and 2) To explore possible reasons for the variation in prevalence of these three NCDs in the different counties. Design, Setting andSubjects: A total of 7,870 households in a representative sample in eight Kenyan counties were screened for the presence of any non-communicable disease. Diagnosis and treatment data on these NCDs was collected and compared using county specific independent data from the 2014 Kenyan Demographic Health Survey (DHS).Main Outcome Measures: Over all the eight surveyed counties, 10.7% of households reported having one or more individuals with an NCD. The county specific prevalence varied from 3% to 30.2%. Of the 7,870 households surveyed, 6.9% reported having a diagnosis of hypertension, 3.2% of asthma, and 2.3% of diabetes.Results: The strongest explanatory variables for the variation in overall prevalence of NCDs related to access to health services and lifestyle risk factors. Conclusion: The prevalence of reported NCDs varies considerably between  counties in Kenya. Reasons may relate to a lack of access to diagnostic facilities or  ifferences in lifestyle risk factors. We recommend a comprehensive field survey of biometric, health access, and lifestyle risk factors to determine the true prevalence and related risk factors for NCDs in Kenya