Estimation of Tuberculosis Risk and Incidence under Upper Room Ultraviolet Germicidal Irradiation in a Waiting Room in a Hypothetical Scenario

Environmental control measures (ventilation, high-efficiency particulate air filtration, and upper room ultraviolet germicidal irradiation [UVGI]) are recommended to effectively control tuberculosis (TB) transmission from unsuspected TB patients in high-risk settings, but the effectiveness of their use is not often clear. This study presents a simulation model for a hypothetical hospital waiting room, in which the number of susceptible immunocompetent people in the waiting room follows a Poisson distribution (M = 5) in either low (annual number of TB patients = 5) or high TB risk settings (annual number of TB patients = 50), and used the model to evaluate the reduction of TB transmission risk by upper room UVGI. An exponential dose-response model was used for TB transmission and a two-zone model was used for evaluating the effect of upper room UVGI. Upper room UVGI reduced TB risk by 1.6-fold at 3 microW/cm2 UV irradiance in the upper room in the low TB risk setting and by 4.1-fold at 15 microW/cm2 UV irradiance in the upper room in the high TB risk setting. Use of upper room UVGI also reduced the mean annual new infection rate from 2.2 to 1.3 infections per year at 3 microW/cm2 and to 0.6 infections per year at 15 microW/cm2 in our hypothetical high-risk settings. The effect of upper room UVGI was sensitive to both vertical air velocity (air mixing) and UV irradiance level. Results from partitioning variability indicate that most variability of TB transmission risk came from waiting time in our hypothetical hospital.     

A Time‐Dependent Risk Assessment for Broken Compact Fluorescent Lamps

Environmental Protection Agency (EPA) ambient air quality guidelines are meant to limit long‐term exposures of toxins to safe levels. Unfortunately, there is little guidance for what constitutes a safe level from a one‐time (or very infrequent) short exposure(s). In the case of mercury, a review of the derivation of the EPA ambient air quality standard shows that it implicitly assumes a tissue burden model. The time dependence of the tissue burden is commonly described in terms of a half‐life, a modeling assumption that presumes that the decline in the tissue burden after a single exposure can be approximately described as an exponential decay. In this article, we use a simple exponential tissue burden model to derive a time‐dependent no observable adverse effect level (NOAEL) for mercury concentrations in air. The model predicts that tissue body burden will asymptotically approach the EPA air quality level for long exposure times, and reach workplace standard levels for exposures of a few hours. The model was used along with data on mercury levels from experimental work done by the Maine Department of Environmental Protection to evaluate the risks from a broken compact fluorescent lamp in a residential setting. Mercury levels approached the NOAEL only when the debris was left in an almost sealed room. Normal common‐sense cleaning measures: removal of debris to an outside area, and ventilation of the room for several minutes, reduced exposures to less than 1% of the NOAEL.     

An Integrated Model of Infection Risk in a Health-Care Environment

Certain respiratory tract infections can be transmitted by hand-to-mucous-membrane contact, inhalation, and/or direct respiratory droplet spray. In a room occupied by a patient with such a transmissible infection, pathogens present on textile and nontextile surfaces, and pathogens present in the air, provide sources of exposure for an attending health-care worker (HCW); in addition, close contact with the patient when the latter coughs allows for droplet spray exposure. We present an integrated model of pertinent source-environment-receptor pathways, and represent physical elements in these pathways as "states" in a discrete-time Markov chain model. We estimate the rates of transfer at various steps in the pathways, and their relationship to the probability that a pathogen in one state has moved to another state by the end of a specified time interval. Given initial pathogen loads on textile and nontextile surfaces and in room air, we use the model to estimate the expected pathogen dose to a HCW's mucous membranes and respiratory tract. In turn, using a nonthreshold infectious dose model, we relate the expected dose to infection risk. The system is illustrated with a hypothetical but plausible scenario involving a viral pathogen emitted via coughing. We also use the model to show that a biocidal finish on textile surfaces has the potential to substantially reduce infection risk via the hand-to-mucous-membrane exposure pathway.     

How hospitals manage operating room delays.

This article reports the background and findings of a study made in late summer of 1987 on the incidence and management of some factors identified as contributing to delays, and thus inefficiency, in operating room utilization.     

SPECTRAL ANALYSIS IN BUSINESS FORECASTING*

Although spectral analysis has previously been discussed in a number of business journals, the discussion has not been detailed enough for non-mathematicians. The objective of this paper is to review in detail the concepts and to go over the computations of spectral analysis as they pertain to forecasting. To gain insight into the model building technique of spectral analysis, a passing comparison with a familiar model–regression–is made. Regression analysis attempts to find a set of independent variables that shed some light on the dependent variable to be forecasted. In other words, if the independent variables have some functional relationship with the dependent variable, a reliable forecast of the dependent variable can then be made. Forecasting using spectral analysis, on the other hand, is based on the assumption that the variation of a time series can be explained by some mixture of sine and cosine waves. Model parameters can then be estimated for these waves and forecasts be made. These parameters have the same property of least squares as in ordinary regression analysis. A transformation of these parameters gives the spectra of the time series. The spectra are related to the explained variation present in regression analysis. An extension of the spectra gives a set of coefficients of an autoregressive forecasting model. This latter model is referred to as the Wiener-Kolmogorov forecasting model.     

Business models as a basis for regulation of financial reporting

The paper observes that the term ‘business model’ has been incorporated in recent financial reporting regulations. The first section of the paper describes various meanings of ‘business model’ and demonstrates that the term has no settled or agreed meaning. The second part of the paper considers the suitability of the term ‘business model’ as a basis for a measurement standard (IFRS 9) or for requirements for narrative reporting and concludes it is not suitable for either purpose. Examples from the UK FTSE 100 index companies are used to illustrate existing usage in narrative reporting, finding varying levels of informativeness of disclosures about business models. The final part of the paper discusses reasons for incorporating an ambiguous and contested term in reporting guidance. It identifies parallels with ambiguity in other branches of financial reporting and the potential utility of ambiguity in allowing consensus to be arrived at on a form of words, apparently tightening up reporting regulation, while allowing participants ‘wiggle room’.     

Modeling the Airborne Infection Risk of Tuberculosis for a Research Facility in eMalahleni,South Africa

A detailed mathematical modeling framework for the risk of airborne infectious disease transmission in indoor spaces was developed to enable mathematical analysis of experiments conducted at the Airborne Infections Research (AIR) facility, eMalahleni, South Africa. A model was built using this framework to explore possible causes of why an experiment at the AIR facility did not produce expected results. The experiment was conducted at the AIR facility from August 31, 2015 to December 4, 2015, in which the efficacy of upper room germicidal ultraviolet (GUV) irradiation as an environmental control was tested. However, the experiment did not produce the expected outcome of having fewer infections in the test animal room than the control room. The simulation results indicate that dynamic effects, caused by switching the GUV lights, power outages, or introduction of new patients, did not result in the unexpected outcomes. However, a sensitivity analysis highlights that significant uncertainty exists with risk of transmission predictions based on current measurement practices, due to the reliance on large viable literature ranges for parameters.     

Shop floor control system for tool rooms

A shop floor control system (SFCS), which is the most important component of any production control system, ff has a direct e ect on the productivity of a tool room. The SFCS presented in this paper aims at streamlining various tool room activities, such as process planning, operations scheduling, loading, progress monitoring, and performance monitoring. The system discussed in this paper is characterized by simplicity and is user friendly. Basic information, consisting of three types of information (order details, process details, and part details), is input through interactive dialogue sessions. On-line updating of the process information is carried out, again through interactive dialogue sessions. The basic input to the system along with the on-line updating enables a number of useful and important reports and documents to be generated ff by the system for e ective control of the shop floor. The reports generated include operations scheduling, process sheet, part list, ffi job card, load pending report, e ciency report, etc. This SFCS is developed for a medium sized tool room in an automotive company and its successful implemention reduced paperwork and improved resource management and has resulted in productivity. It can be said that this system offers a first venture into computer integrated manufacturing (CIM) for a tool room.     

A DYNAMIC PROGRAMMING MODEL FOR PERIODICAL SELECTION

This paper presents a model for choosing the periodical collection in a reading room. The model consists of two stages. In the first stage the probability distribution of contacts by users with a given periodical is developed and employed to determine the utility of the periodical. In the second stage the problem of choosing an optimum periodical collection is formulated as a capital budgeting problem and solved with the aid of dynamic programming. The implementation of this model at the University of Connecticut is described in detail.     

带货物权重的车辆路径问题及遗传算法

考虑一个分销中心、多个零售商组成的分销网络系统中具有柔性车辆能力的带货物权重的车辆路径问题.并根据车辆的满载情况采用了不同的运输策略,即单点运输和多点运输方式.在多点运输方式下,与以往诸多研究不同的是,文章建立了一种基于货物权重的VRP模型——WVRP,即在安排车辆线路时每个零售商的货物需求量也作为一个因素考虑,尽可能使车辆优先供货需求量较大的零售商.最后,针对问题的性质,开发了一种基于划分的遗传算法PB-GA对问题进行求解,并与一般遗传算法及常用的启发式算法进行了分析比较.     

The use of economic appraisal in transportation analysis

This paper surveys the use of economic appraisal techniques in the field of transportation. After surveying the history of such approaches, a critical assessment is offered of the most recent contributions to the debate, centering on the 1977 Leitch Report. The limited room for manoeuvre in making local assessments is highlighted: national policy considerations are seen as frequently dominating the local choice. While most of the debate on the ‘inadequacies’ of cost-benefit have focussed on ‘intangible’ items, the author argues for a much closer look at the ‘hard’ data on the value of time-savings and accident costs. Some of the Leitch committee's proposals are found wanting in this respect. In the wider context, a plea is made for the use of common criteria for assessing projects throughout the entire transport sector. Only in this way can misallocation of resources be minimised.     

我国的通货膨胀与名义利率粘性:长期与短期费雪效应

弱费雪效应和名义利率粘性是货币政策有效的前提。本文使用傅里叶变换处理实际利率的时变性，扩展协整模型用以考察长期的费雪效应，并建立门限误差修正模型区分长期和短期的费雪效应，刻画名义利率短期的动态调整特征。基于我国1990年1月至2017年12月的月度数据研究发现：（1）我国名义利率和通货膨胀之间存在长期的弱费雪效应；（2）名义利率的短期动态调整特征存在显著的双重门限效应，在名义利率过度高于均衡值时会出现显著而快速的调整，而当名义利率低于均衡值或处于中间机制时，均没有发现显著的调整，即名义利率存在粘性。研究结果表明：当前阶段数量型货币政策在我国依然有效，因而存在综合使用数量型货币政策和价格型货币政策的空间。     

Energy modelling for technology assessment: the MARKAL approach

The primary objective of energy policy in many countries is to change the structure of their energy systems so as to reduce the dependence on imported oil. A large amount of funds is spent on energy research and development. The technologies competing for such funds have widely varying characteristics. These relate to costs and benefits, technical performance, environmental effects, the requirements for land, water and materials and the impact on employment. It is necessary to analyse these effects in some detail before decisions on technology programmes can be made. A complete assessment of the possible value of a particular technology cannot be made on an individual basis. It is necessary to consider many technologies simultaneously, competing against each other for various shares of the energy market. However, analysing the behaviour of the entire energy system requires the handling of an extensive amount of data and can only be done effectively with the help of a computerised system. The model, MARKAL, described in this paper is a multi-period linear programming model which has been developed and applied by 15 OECD countries for the purpose of energy technology research and development planning. Examples of the use of the model for this purpose are given both for the group as a whole and for individual countries. The model is structured so that an exogenously specified set of end-use demands must be satisfied given available technologies and energy supplies. The model allows for substitution possibilities in both the energy supply and demand sectors. A feature of the model is the use of varying objective functions such as minimum discounted costs, oil imports, or environmental effluents. These can be used individually or in combination in trade-off situations. The broader question of the use of energy modelling for technology assessment, including its limitations, is also discussed with particular reference to the insights that can be gained from the MARKAL model. Information from the MARKAL model has been used by the International Energy Agency to assist it in formulating a strategy for energy research development and demonstration.     

Hierarchical model to design manufacturing systems applied to a metal-mechanic company

This paper describes the application of a model to design and manage the manufacturing process through an integrated system, using a Hierarchical methodology-by means of different aggregation and disaggregation stages with an appropriate time horizon. The hierarchical model obtained allows interfacing between the master schedule and the schedule of the orders. At each level of the hierarchical model some decisions have to be made in order to design the manufacturing system, but having a model that also takes into consideration the management of the system. To do this it is necessary to use aggregated information concerned with the level at which decisions are made. It is obtained from the database, which contains the information at the highest level of aggregation. This model has been applied to a metal mechanic company, that makes final products such as car washers, etc. The benefits of this approach for the company are addressed in this paper.     

现阶段我国政府债务“警戒线”的反思及债务风险的防范

通常人们依据债务规模的“警戒线”来衡量政府债务风险 ,认为我国政府债务风险已经较高。本文对此作了探讨并得出结论：前面的结论实际上很难成立 ,我国积极财政政策还有较大的空间。我国债务风险主要在于经济增长对债务资金可能形成的持久依赖。防范债务风险的根本措施是坚持深化改革、促进结构调整 ,主要依靠民间投资和消费拉动经济增长。国债资金应该用于支持体制改革和结构调整。随着积极财政政策在我国的运用 ,对我国政府债务风险的讨论也越来越多。一般对债务风险的判断都是基于国债负担率、赤字率、债务依存度、偿债率这样一些指标。…     

Partially Flexible Operating Rooms for Elective and Emergency Surgeries

In hospitals, the management of operating rooms faces a trade‐off between the need to be responsive to emergency surgeries and to conduct scheduled elective surgeries efficiently. Operating rooms can be configured as flexible and handle both electives and emergencies, or as dedicated to focus on either electives or emergencies. With flexible rooms, the prioritization of emergencies over scheduled electives can lead to schedule disruptions. Focused rooms can lead to imbalances between capacity and surgery workload. Whereas hospital administrators typically handle this trade‐off by employing either flexible rooms (complete flexibility) or dedicated rooms (complete focus), we investigate whether a combination of flexible and dedicated rooms (partial flexibility) could be a preferable alternative. The ensuing question is what is the right combination of flexible and dedicated rooms? A versatile simulation model is developed to evaluate different resource allocation policies under various environmental parameters and performance metrics, including patient wait time, staff overtime, and operating room utilization. The main result is that partial flexibility configurations outperform both complete flexibility and complete focus policies by providing solutions with improved values of expected wait time for both emergency and elective patients.     

Cross-cultural industrial relations: An empirical examination

This paper is born out of research conducted in Hong Kong, Malaysia, and India between 1987 and 1990. It is an attempt to empirically test and extend the scope of a model formulated in England in 1977. The original model postulated that managerial behavior towards industrial relations issues, on an organizational or micro level, could be predicted if the managerial style could be properly predicated within the matrix of the model. The present study uses the model to see if similar prediction (or in any case, generalization) can be made on a macro level. The findings reveal that a certain degree of generalization can be empirically sustained in so far as the style of managers in the three countries is concerned. To that extent the paper is a contribution to the corpus of thought on the subject of managerial beliefs and provides valuable insight for the student of human resources management especially in the area of industrial relations and corporate policy.     

Validation and Application of Models to Predict Facemask Influenza Contamination in Healthcare Settings

Facemasks are part of the hierarchy of interventions used to reduce the transmission of respiratory pathogens by providing a barrier. Two types of facemasks used by healthcare workers are N95 filtering facepiece respirators (FFRs) and surgical masks (SMs). These can become contaminated with respiratory pathogens during use, thus serving as potential sources for transmission. However, because of the lack of field studies, the hazard associated with pathogen‐exposed facemasks is unknown. A mathematical model was used to calculate the potential influenza contamination of facemasks from aerosol sources in various exposure scenarios. The aerosol model was validated with data from previous laboratory studies using facemasks mounted on headforms in a simulated healthcare room. The model was then used to estimate facemask contamination levels in three scenarios generated with input parameters from the literature. A second model estimated facemask contamination from a cough. It was determined that contamination levels from a single cough (≈19 viruses) were much less than likely levels from aerosols (4,473 viruses on FFRs and 3,476 viruses on SMs). For aerosol contamination, a range of input values from the literature resulted in wide variation in estimated facemask contamination levels (13–202,549 viruses), depending on the values selected. Overall, these models and estimates for facemask contamination levels can be used to inform infection control practice and research related to the development of better facemasks, to characterize airborne contamination levels, and to assist in assessment of risk from reaerosolization and fomite transfer because of handling and reuse of contaminated facemasks.     

财务保守行为:基于中国上市公司的实证研究

财务保守行为是指企业在较长的一段时间内持续地采用低财务杠杆的财务政策的一种行为。与传统的资本结构管理观点相比,保守的财务政策更加注重获得财务灵活性以防范风险和捕捉未来的投资机会,是一种崭新的资本结构管理的观点。本文运用LOGIT非线性回归模型,基于中国上市公司的经验数据,分别从产业组织、资本市场和治理结构3个方面考察了影响财务保守行为的主要因素并进行了理论分析。实证结果表明:由产品市场竞争决定的企业本身的内源融资能力是财务保守行为产生的最为重要的原因,而这种能力主要取决于企业所处的市场环境、政府管制和产业组织情况;资本市场的估价状况对于财务保守行为有重大的影响,我国股价高估的资本市场环境,以及二元割裂、一股独大的治理结构使得非流通股股东偏好从增发和配股中获取利益,客观上造成了上市公司的股权融资偏好行为,而这种偏好表现在资本结构上,就是财务保守行为,可以称之为企业融资战略对于财务保守行为的影响;最后,我们没有发现足够的证据支持财务保守行为和公司竞争战略之间有足够的联系,说明我国的上市公司在资本结构管理方面较少地考虑到资本结构和产品市场竞争之间的互动与协调,企业战略管理的水平尚待进一步地提高。     

A Methodology for Modeling Regional Terrorism Risk

Over the past decade, terrorism risk has become a prominent consideration in protecting the well‐being of individuals and organizations. More recently, there has been interest in not only quantifying terrorism risk, but also placing it in the context of an all‐hazards environment in which consideration is given to accidents and natural hazards, as well as intentional acts. This article discusses the development of a regional terrorism risk assessment model designed for this purpose. The approach taken is to model terrorism risk as a dependent variable, expressed in expected annual monetary terms, as a function of attributes of population concentration and critical infrastructure. This allows for an assessment of regional terrorism risk in and of itself, as well as in relation to man‐made accident and natural hazard risks, so that mitigation resources can be allocated in an effective manner. The adopted methodology incorporates elements of two terrorism risk modeling approaches (event‐based models and risk indicators), producing results that can be utilized at various jurisdictional levels. The validity, strengths, and limitations of the model are discussed in the context of a case study application within the United States.