Exciton spin dynamics and photoluminescence polarization of CdSe/CdS dot-in-rod nanocrystals in high magnetic fields

The exciton spin dynamics and polarization properties of the related emission are investigated in colloidal CdSe/CdS dot-in-rod (DiR) and spherical core/shell nanocrystal (NC) ensembles by magneto-optical photoluminescence (PL) spectroscopy in magnetic fields up to 15 T. It is shown that the degree of circular polarization (DCP) of the exciton emission induced by the magnetic field is affected by the NC geometry as well as the exciton fine structure and can provide information on nanorod orientation. A theory to describe the circular and linear polarization properties of the NC emission in magnetic field is developed. It takes into account phonon mediated coupling between the exciton fine structure states as well as the dielectric enhancement effect resulting from the anisotropic shell of DiR NCs. This theoretical approach is used to model the experimental results and allows us to explain most of the measured features. The spin dynamics of the dark excitons is investigated in magnetic fields by time-resolved photoluminescence. The results highlight the importance of confined acoustic phonons in the spin relaxation of dark excitons. The bare core surface as well as the core/shell interface give rise to an efficient spin relaxation channel, while the surface of core/shell NCs seems to play only a minor role.Comment: 18 pages, 15 figure

Integrating Chinese and African Culture into Human Resource Management Practice to Enhance Employee Job Satisfaction

Foreign enterprises find themselves working in multicultural environments. This is the case that most foreign organizations find themselves in when investing in African countries that calls for integrating different cultural values into the management of human resources in order to enhance job satisfaction consequently business performance. Since her establishment China has had good relationship with Africa both economically and politically in her endeavour to foster international relationships. China’s presence in Africa has been significant in terms of investments, transferring management practices and creating new integration of different cultural values. Research has shown that there are similarities between Africa’s Ubuntu culture and the Chinese Confucius philosophy that might form a strong pillar for Chinese investments in this part of the world. However, it is envisioned that there are inherent challenges faced by both Chinese and African practitioners that might call for revolutionary actions to untangle the barriers in other cultural dimensions such as work attitudes, trust, the place of work in one’s life and what employees’ value in work in this complex management transfer process. Hofstede’s cultural dimensions and Hofstede and Bond (1988) Confucian Dynamism values that have been widely used in studying culture’s influence in cross cultural management across the world and Asia respectively are used as a basis for comparing African and Chinese culture to reveal areas of convergence or divergence. It is generally recognized that culturally insensitive attitudes and behaviours stemming from ignorance or from misguided beliefs not only are inappropriate but also often cause international business failures. Therefore, it is argued that an awareness of cultural differences is essential for HR managers at headquarters as well as in the host location. Chinese firms operating in Africa could be more successful when they integrate Chinese and African cultures in managing HR activities like hiring, promoting, rewarding, and dismissal in order to influence employee job satisfaction in a host country in Africa.  This paper examines the transfer of Chinese management practices, integration of Chinese and African cultures in fostering a climate of job satisfaction among employees to enhance organization performance. This paper is aimed at setting a research agenda for further research in Sino-Africa business relationships. Key Words: China, Africa, Culture, Investment, job satisfaction, performance, value orientation

Eulerian CFD modeling of nozzle geometry effects on ECN Sprays A and D: assessment and analysis

This is the author's version of a work that was accepted for publication in International Journal of Engine Research. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published as https://doi.org/10.1177/1468087419882500.[EN] Diesel spray modeling is a multi-scale problem with complex interactions between different flow regions, that is, internal nozzle flow, near-nozzle region and developed spray, including evaporation and combustion. There are several modeling approaches that have proven particularly useful for some spray regions although they have struggled at other areas, while Eulerian modeling has shown promise in dealing with all characteristics at a reasonable computational effort for engineering calculations. In this work, the sigma -Y single-fluid diffuse-interface model, based on scale separation assumptions at high Reynolds and Weber numbers, is used to simulate the engine combustion network Sprays A and D within a Reynolds-averaged Navier-Stokes turbulence modeling approach. The study is divided into two parts. First of all, the larger diameter Spray D is modeled from the nozzle flow till evaporative spray conditions, obtaining successful prediction of numerous spray metrics, paying special attention to the near-nozzle region where spray dispersion and interfacial surface area can be validated against measurements conducted at the Advanced Photon Source at Argonne National Laboratory, including both the ultra-small-angle X-ray scattering and the X-ray radiography. Afterwards, an analysis of the modeling predictions is made in comparison with previous results obtained for Spray A, considering the nozzle geometry effects in the modeling behavior.The authors thank the freely shared X-ray radiography and ultra-small-angle X-ray scattering measurements performed at Argonne National Laboratory by the following authors: Daniel J. Duke, Jan Ilavsky, Katarzyna E. Matusik., Brandon A. Sforzo., Alan L. Kastengren and Christopher F. Powell. They also thankfully acknowledge the computer resources at Picasso and the technical support provided by Universidad de Malaga (UMA; RES-FI-2018-1-0039).Pandal, A.; García-Oliver, JM.; Pastor Enguídanos, JM. (2020). Eulerian CFD modeling of nozzle geometry effects on ECN Sprays A and D: assessment and analysis. International Journal of Engine Research. 21(1):73-88. https://doi.org/10.1177/1468087419882500S7388211PAYRI, R., GARCIA, J., SALVADOR, F., & GIMENO, J. (2005). Using spray momentum flux measurements to understand the influence of diesel nozzle geometry on spray characteristics. Fuel, 84(5), 551-561. doi:10.1016/j.fuel.2004.10.009Payri, R., Salvador, F. J., Gimeno, J., & Zapata, L. D. (2008). Diesel nozzle geometry influence on spray liquid-phase fuel penetration in evaporative conditions. Fuel, 87(7), 1165-1176. doi:10.1016/j.fuel.2007.05.058Payri, R., Salvador, F. J., Gimeno, J., & de la Morena, J. (2009). Effects of nozzle geometry on direct injection diesel engine combustion process. Applied Thermal Engineering, 29(10), 2051-2060. doi:10.1016/j.applthermaleng.2008.10.009Payri, F., Payri, R., Salvador, F. J., & Martínez-López, J. (2012). A contribution to the understanding of cavitation effects in Diesel injector nozzles through a combined experimental and computational investigation. Computers & Fluids, 58, 88-101. doi:10.1016/j.compfluid.2012.01.005Kastengren, A. L., Powell, C. F., Wang, Y., Im, K.-S., & Wang, J. (2009). 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International Journal of Multiphase Flow, 83, 162-171. doi:10.1016/j.ijmultiphaseflow.2016.04.003Pandal, A., Payri, R., García-Oliver, J. M., & Pastor, J. M. (2017). Optimization of spray break-up CFD simulations by combining Σ-Y Eulerian atomization model with a response surface methodology under diesel engine-like conditions (ECN Spray A). Computers & Fluids, 156, 9-20. doi:10.1016/j.compfluid.2017.06.022Pandal, A., García-Oliver, J. M., Novella, R., & Pastor, J. M. (2018). A computational analysis of local flow for reacting Diesel sprays by means of an Eulerian CFD model. International Journal of Multiphase Flow, 99, 257-272. doi:10.1016/j.ijmultiphaseflow.2017.10.010Payri, R., Ruiz, S., Gimeno, J., & Martí-Aldaraví, P. (2015). Verification of a new CFD compressible segregated and multi-phase solver with different flux updates-equations sequences. Applied Mathematical Modelling, 39(2), 851-861. doi:10.1016/j.apm.2014.07.011Salvador, F. J., Gimeno, J., Pastor, J. 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Analyzing the Structure and Function of Novel Cytochromes from a Natural Microbial Community

The Richmond mine in Iron Mountain, California, provides an unusual ecosystem suitable for the growth of microbial biofilms which produce many unique proteins. Through iron oxidation, these proteins facilitate acid mine drainage (AMD). Because this habitat is extremely acidic, survival is an extraordinary feat and the process of environmental selection is rare. In order to understand the mechanisms by which these organisms oxidize iron and gain electrons for energy, biochemical studies were applied. More specifically, column chromatography, spectrophotometry, and gel electrophoresis were used to determine the proteins present in different biofilms. Two specific locations of the mine researched were the AB drift and Ultraback C (UBC), which were both found to contain at least five different types of protein and a large amount of heme-bound cytochromes. Another application of these methods was to investigate proteins playing a major role within the community; one protein selected was cytochrome 579 (Cyt{sub 579}) due to its abundance in the biofilm, iron oxidizing potential, and signature absorbance of 579nm. The structure and function of Cyt{sub 579} could be characterized by the isolation of its heme, which was completed using column chromatography; however, one of the challenges has been liberating the heme from the column. Further research, including acid-base and temperature profiling of Cyt{sup 579} should help elucidate its structural changes within alternate environments and metabolism within the community

Enriching Visual with Verbal Explanations for Relational Concepts -- Combining LIME with Aleph

With the increasing number of deep learning applications, there is a growing demand for explanations. Visual explanations provide information about which parts of an image are relevant for a classifier's decision. However, highlighting of image parts (e.g., an eye) cannot capture the relevance of a specific feature value for a class (e.g., that the eye is wide open). Furthermore, highlighting cannot convey whether the classification depends on the mere presence of parts or on a specific spatial relation between them. Consequently, we present an approach that is capable of explaining a classifier's decision in terms of logic rules obtained by the Inductive Logic Programming system Aleph. The examples and the background knowledge needed for Aleph are based on the explanation generation method LIME. We demonstrate our approach with images of a blocksworld domain. First, we show that our approach is capable of identifying a single relation as important explanatory construct. Afterwards, we present the more complex relational concept of towers. Finally, we show how the generated relational rules can be explicitly related with the input image, resulting in richer explanations

The impact of loss to follow-up in the Dutch organised HPV-based cervical cancer screening programme

Loss to follow-up (LTFU) within cervical screening programmes can result in missed clinically relevant lesions, potentially reducing programme effectiveness. To examine the health impact of losing women during the screening process, we determined the proportion of women LTFU per step of the Dutch hrHPV-based screening programme. We then determined the probability of being LTFU by age, screening history and sampling method (self- or clinician-sampled) using logistic regression analysis. Finally, we estimated the number of missed CIN2+/3+ lesions per LTFU moment by using the CIN-risk in women compliant with follow-up. Data from the Dutch nationwide pathology databank (Palga) was used. Women eligible for screening in 2017 and 2018 were included (N = 840,428). For clinician collected (CC) samples, the highest proportion LTFU was found following ‘referral advice for colposcopy’ (5.5% after indirect referral; 3.8% after direct referral). For self-sampling, the highest proportions LTFU were found following the advice for repeat cytology (13.6%) and after referral advice for colposcopy (8.2% after indirect referral; 4.3% after direct referral). Self-sampling users and women with no screening history had a higher LTFU-risk (OR: 3.87, CI: 3.55–4.23; OR: 1.39, CI: 1.20–1.61) compared to women that used CC sampling and women that have been screened before, respectively. Of all women LTFU in 2017/18, the total number of potentially missed CIN2+ was 844 (21% of women LTFU). Most lesions were missed after ‘direct referral for colposcopy’ (N = 462, 11.5% of women LTFU). So, this indicates a gap between the screening programme and clinical care which requires further attention, by improving monitoring of patients after referral.</p

The impact of loss to follow-up in the Dutch organised HPV-based cervical cancer screening programme

Loss to follow-up (LTFU) within cervical screening programmes can result in missed clinically relevant lesions, potentially reducing programme effectiveness. To examine the health impact of losing women during the screening process, we determined the proportion of women LTFU per step of the Dutch hrHPV-based screening programme. We then determined the probability of being LTFU by age, screening history and sampling method (self- or clinician-sampled) using logistic regression analysis. Finally, we estimated the number of missed CIN2+/3+ lesions per LTFU moment by using the CIN-risk in women compliant with follow-up. Data from the Dutch nationwide pathology databank (Palga) was used. Women eligible for screening in 2017 and 2018 were included (N = 840,428). For clinician collected (CC) samples, the highest proportion LTFU was found following ‘referral advice for colposcopy’ (5.5% after indirect referral; 3.8% after direct referral). For self-sampling, the highest proportions LTFU were found following the advice for repeat cytology (13.6%) and after referral advice for colposcopy (8.2% after indirect referral; 4.3% after direct referral). Self-sampling users and women with no screening history had a higher LTFU-risk (OR: 3.87, CI: 3.55–4.23; OR: 1.39, CI: 1.20–1.61) compared to women that used CC sampling and women that have been screened before, respectively. Of all women LTFU in 2017/18, the total number of potentially missed CIN2+ was 844 (21% of women LTFU). Most lesions were missed after ‘direct referral for colposcopy’ (N = 462, 11.5% of women LTFU). So, this indicates a gap between the screening programme and clinical care which requires further attention, by improving monitoring of patients after referral.</p

Laboratory Focus on Improving the Culture of Biosafety: Statewide Risk Assessment of Clinical Laboratories That Process Specimens for Microbiologic Analysis

The Wisconsin State Laboratory of Hygiene challenged Wisconsin laboratories to examine their biosafety practices and improve their culture of biosafety. One hundred three clinical and public health laboratories completed a questionnaire-based, microbiology-focused biosafety risk assessment. Greater than 96% of the respondents performed activities related to specimen processing, direct microscopic examination, and rapid nonmolecular testing, while approximately 60% performed culture interpretation. Although they are important to the assessment of risk, data specific to patient occupation, symptoms, and travel history were often unavailable to the laboratory and, therefore, less contributory to a microbiology-focused biosafety risk assessment than information on the specimen source and test requisition. Over 88% of the respondents complied with more than three-quarters of the mitigation control measures listed in the survey. Facility assessment revealed that subsets of laboratories that claim biosafety level 1, 2, or 3 status did not possess all of the biosafety elements considered minimally standard for their respective classifications. Many laboratories reported being able to quickly correct the minor deficiencies identified. Task assessment identified deficiencies that trended higher within the general (not microbiology-specific) laboratory for core activities, such as packaging and shipping, direct microscopic examination, and culture modalities solely involving screens for organism growth. For traditional microbiology departments, opportunities for improvement in the cultivation and management of highly infectious agents, such as acid-fast bacilli and systemic fungi, were revealed. These results derived from a survey of a large cohort of small- and large-scale laboratories suggest the necessity for continued microbiology-based understanding of biosafety practices, vigilance toward biosafety, and enforcement of biosafety practices throughout the laboratory setting