Nanomatemàtiques: modelització matemàtica a la nanoescala

En aquest article exposem tres problemes estudiats recentment al grup de Matemàtica Industrial del Centre de Recerca Matemàtica, en els quals l'aproximació del continu resulta vàlida per a descriure fenòmens a la nanoescala: 1. Transferència de calor en nanofluids: els resultats experimentals que confirmen l'increment de la capacitat de transferir calor dels nanofluids respecte dels fluids estàndard són sovint contradictoris. Mitjançant una anàlisi de capa límit mostrarem com el model matemàtic utilitzat en nombroses ocasions per justificar l'increment en la transferència de calor dels nanofluids preveu, de fet, una disminució d'aquesta propietat. 2. Fusió de nanopartícules: les nanopartícules mostren un increment abrupte de la velocitat de transició de fase a mesura que el seu radi decreix. Presentarem un model matemàtic que descriu aquest fenomen. El model preveu temps totals de transició sòlid-líquid que concorden amb les observacions experimentals. 3. Increment del flux d'un fluid en nanotubs de carboni (CNT): mostrarem que els resultats experimentals sobre l'increment de flux en nanotubs de carboni es poden explicar mitjançant les equacions estàndard de la dinàmica de fluids amb la incorporació d'una capa d'extinció (depletion layer) a la interfície entre el fluid i el sòlid.In this paper we discuss three problems recently studied within the Industrial Maths Research Group at the Centre de Recerca Matemàtica, where continuum theory may be applied to describe nanoscale phenomena: 1. Heat transfer with nanofluids: Experimental results concerning the remarkable heat transfer characteristics of nanofluids are at times contradictory. We apply a boundary layer analysis to show that a standard model which has been used by many authors to predict an improvement in heat transfer with increasing nanoparticle concentration in fact shows a decrease. 2. Nanoparticle melting: Nanoparticles often exhibit a sharp increase in melting rate as the size decreases. A mathematical model will be presented which predicts this phenomena and explains the experimentally observed abrupt melting of the smallest nanoparticles. 3. Enhanced flow in carbon nanotubes (CNTs): This model shows that the experimentally observed enhancement can be explained using standard flow equations but with a depletion layer between the liquid and solid interfaces. The results also provide one physical explanation for the Navierslip condition

Irreconcilable differences? : strategic human resource management and employee well-being

The transition from ‘personnel’ to ‘human resource management’ took place in Australia in the latter part of the twentieth century. The change in nomenclature reflects a change in the nature of the work: from an employee-centred role to a management-centred role. In this paper we examine the relationship between these two roles, with a particular emphasis on their compatibility. Using interview data we find that HR managers devote considerable time to employee-centred activities. HR managers philosophically reconcile these activities with their responsibilities as a strategic partner by identifying the benefits of their employee-centred efforts for management. HR managers do, however, experience some operational challenges when they attempt to be a strategic partner and simultaneously promote employee well-being.

Nanomatemàtiques: modelització matemàtica a la nanoescala

En aquest article exposem tres problemes estudiats recentment al grup de Matemàtica Industrial del Centre de Recerca Matemàtica, en els quals l'aproximació del continu resulta vàlida per a descriure fenòmens a la nanoescala: 1. Transferència de calor en nanofluids: els resultats experimentals que confirmen l'increment de la capacitat de transferir calor dels nanofluids respecte dels fluids estàndard són sovint contradictoris. Mitjançant una anàlisi de capa límit mostrarem com el model matemàtic utilitzat en nombroses ocasions per justificar l'increment en la transferència de calor dels nanofluids preveu, de fet, una disminució d'aquesta propietat. 2. Fusió de nanopartícules: les nanopartícules mostren un increment abrupte de la velocitat de transició de fase a mesura que el seu radi decreix. Presentarem un model matemàtic que descriu aquest fenomen. El model preveu temps totals de transició sòlid-líquid que concorden amb les observacions experimentals. 3. Increment del flux d'un fluid en nanotubs de carboni (CNT): mostrarem que els resultats experimentals sobre l'increment de flux en nanotubs de carboni es poden explicar mitjançant les equacions estàndard de la dinàmica de fluids amb la incorporació d'una capa d'extinció (depletion layer) a la interfície entre el fluid i el sòlid.In this paper we discuss three problems recently studied within the Industrial Maths Research Group at the Centre de Recerca Matemàtica, where continuum theory may be applied to describe nanoscale phenomena: 1. Heat transfer with nanofluids: Experimental results concerning the remarkable heat transfer characteristics of nanofluids are at times contradictory. We apply a boundary layer analysis to show that a standard model which has been used by many authors to predict an improvement in heat transfer with increasing nanoparticle concentration in fact shows a decrease. 2. Nanoparticle melting: Nanoparticles often exhibit a sharp increase in melting rate as the size decreases. A mathematical model will be presented which predicts this phenomena and explains the experimentally observed abrupt melting of the smallest nanoparticles. 3. Enhanced flow in carbon nanotubes (CNTs): This model shows that the experimentally observed enhancement can be explained using standard flow equations but with a depletion layer between the liquid and solid interfaces. The results also provide one physical explanation for the Navierslip condition

Dealing with distressed employees A human resouce [sic] managers perspective

Human resource managers undertake a variety of tasks, including the provision of advice to employees. This can include advice about employment rights and responsibilities as well as on ‘soft’ issues, such as when an employee is upset or concerned about something. Currently HR managers are encouraged to focus on the contribution of an organisation’s human resources to the overall performanance of the organisation, which suggests that HR managers might now be less willing to deal with distressed employees and their soft issues. We find that Australian HR managers spend a significant amount of time dealing with distressed employees who are concerned about a very broad range of personal and work related issues. Contrary to expectations, we find that most HR managers suffer no ill effects as a consequence of their constant exposure to distressed employees

Impact of an ultrabroadband emergency department telemedicine system on the care of acutely ill patients and clinicians' work

Objectives: To evaluate whether introduction of an emergency department (ED) telemedicine system changed patient management and outcome indicators and to investigate clinicians' perceptions of the impact of the system on care provided and on their work. Design: Before-and-after study of use of the Virtual Critical Care Unit (ViCCU), which uses an ultrabroadband connection allowing real-time audiovisual communication between clinicians at distant sites. Semi-structured interviews were conducted with medical and nursing staff at the end of the study. Participants and setting: The ViCCU intervention commenced on 1 January 2004. Our study was conducted in the EDs of an 85-bed district hospital and a 420-bed metropolitan tertiary hospital. It involved all acutely ill patients requiring urgent care (defined by triage category and grouped into critical care, major trauma and moderate trauma) who were treated during the 12 months before (n = 169) and 18 months after (n = 181) the intervention at the district hospital. Thirty-one of 33 clinicians (doctors and nurses) participating at the two hospitals took part in interviews at the end of the study. Main outcome measures: Changes in patterns of management (disposition [admission, discharge or transfer], treatment times, number of procedures) and outcomes (rapid acute physiology scores, hours on ventilation or in intensive care, length of stay). Results: Patient disposition remained unaltered for major trauma patients. For critical care patients, admissions fell significantly (54% to 30%), transfers increased (21% to 39%), and more procedures were performed. For moderate trauma patients, discharges increased significantly (45% to 63%), transfers decreased (48% to 25%) and treatment times were longer. No significant changes were found in outcome indicators. Clinicians reported that the ViCCU allowed greater support to remote clinicians. Specialists reported increased workloads and feelings of greater responsibility for patients at the district hospital. Nurses at the district site reported reduced stress, but district doctors reported some loss of autonomy. Conclusions: The ViCCU appears most effective for moderate trauma patients, with associated reductions in admissions and transfers. Large-scale trials of telemedicine systems that include measurements of both patient care and impact on clinicians' work are required.5 page(s

Association between dietary intake and function in amyotrophic lateral sclerosis

IMPORTANCE There is growing interest in the role of nutrition in the pathogenesis and progression of amyotrophic lateral sclerosis (ALS). OBJECTIVE To evaluate the associations between nutrients, individually and in groups, and ALS function and respiratory function at diagnosis. DESIGN, SETTING, AND PARTICIPANTS A cross-sectional baseline analysis of the Amyotrophic Lateral Sclerosis Multicenter Cohort Study of Oxidative Stress study was conducted from March 14, 2008, to February 27, 2013, at 16 ALS clinics throughout the United States among 302 patients with ALS symptom duration of 18 months or less. EXPOSURES Nutrient intake, measured using a modified Block Food Frequency Questionnaire (FFQ). MAIN OUTCOMES AND MEASURES Amyotrophic lateral sclerosis function, measured using the ALS Functional Rating Scale-Revised (ALSFRS-R), and respiratory function, measured using percentage of predicted forced vital capacity (FVC). RESULTS Baseline data were available on 302 patients with ALS (median age, 63.2 years [interquartile range, 55.5-68.0 years]; 178 men and 124 women). Regression analysis of nutrients found that higher intakes of antioxidants and carotenes from vegetables were associated with higher ALSFRS-R scores or percentage FVC. Empirically weighted indices using the weighted quantile sum regression method of "good" micronutrients and "good" food groups were positively associated with ALSFRS-R scores (β [SE], 2.7 [0.69] and 2.9 [0.9], respectively) and percentage FVC (β [SE], 12.1 [2.8] and 11.5 [3.4], respectively) (all P < .001). Positive and significant associations with ALSFRS-R scores (β [SE], 1.5 [0.61]; P = .02) and percentage FVC (β [SE], 5.2 [2.2]; P = .02) for selected vitamins were found in exploratory analyses. CONCLUSIONS AND RELEVANCE Antioxidants, carotenes, fruits, and vegetableswere associated with higher ALS function at baseline by regression of nutrient indices and weighted quantile sum regression analysis.We also demonstrated the usefulness of the weighted quantile sum regression method in the evaluation of diet. Those responsible for nutritional care of the patient with ALS should consider promoting fruit and vegetable intake since they are high in antioxidants and carotenes