695915 research outputs found
Sort by
Joint 3D Trajectory and Power Optimization for UAV-aided mmWave MIMO-NOMA Networks
No full textThis paper considers an unmanned aerial vehicle (UAV)-aided millimeter Wave (mmWave) multiple-input-multiple-output (MIMO) non-orthogonal multiple access (NOMA) system, where a UAV serves as a flying base station (BS) to provide wireless access services to a set of Internet of Things (IoT) devices in different clusters. We aim to maximize the downlink sum rate by jointly optimizing the three-dimensional (3D) placementof the UAV, beam pattern and transmit power. To address this problem, we first transform the non-convex problem into a total path loss minimization problem, and hence the optimal 3D placement of the UAV can be achieved via standard convex optimization techniques. Then, the multiobjective evolutionary algorithm based on decomposition (MOEA/D) based algorithm is presented for the shaped-beam pattern synthesis of an antenna array. Finally, by transforming the original problem into an optimal power allocation problem under the fixed 3D placement of the UAV and beam pattern, we derive the closed-form expression of transmit power based on Karush-Kuhn-Tucker (KKT) conditions. In addition, inspired by fraction programming (FP), we propose a FP-based suboptimal algorithm to achieve a near-optimal performance. Numerical results demonstrate that the proposed algorithm achieves a significant performance gain in terms of sum rate for all IoT devices, as compared with orthogonal frequency division multiple access (OFDMA) scheme
New Inscriptions in Aramaic/Early Syriac and Greek from the Cemeteries of Edessa
No full textAn editio princeps of new inscriptions in Aramaic/Early Syriac andGreek from the Cemeteries of Edess
Corporate Purpose: Fact or Fiction? Myth or Reality? The Honourable Merchant as the Historic Basis of Corporate Purpose
No full textEspecially since the financial market crisis, the call for responsible corporate management hasbecome louder. Citizens in many countries fear that existing control mechanisms might not beenough to put a stop to financial gamblers in an ethics-void context in the future. To this extent, thefinancial crisis revealed both societal and corporate deficiencies in the basic understanding ofresponsible, sustainable, honourable and thus successful, corporate leadership.The paper shows that Corporate Purpose and the principles of Honourable Merchants coincide andcome into play. The guiding principles assume that responsible behaviour enacted by those inleadership position is the basis for sustainable economic success and social peace in society. Whilemuch of this had been lost as social responsibility became more codified in law rather than driven bypractice and collective value, today we may be seeing a move back from legal doctrine to moralsuasion and collective value based action
The Potential for Moral Hazard Behavior in Irrigation Decisions under Crop Insurance
No full textThe design of federal crop insurance has attracted the interest and attention of manyeconomists and policymakers in the United States. Moral hazard is a frequently cited concern, asinsurance may reduce the incentive for farmers to manage properly their agricultural operation.Moral hazard could play a role in irrigation decisions by incentivizing a farmer to choose ariskier irrigation management strategy, potentially affecting the long-term sustainability of waterresources. We use numerical simulation to determine if insurance coverage affects incentives onseasonal irrigation use. Results show that the potential for moral hazard at current costs andpolicy parameters is low, but that there is potential for moral hazard behavior when the cost ofirrigation is high. Hence, conservation policies that increase the cost of irrigation cost (e.g., awater tax) may amplify the potential for moral hazard. In most cases, crop insurance provides asecondary effect that reduces irrigation use in addition to the direct water tax effect, although thisreduction comes at increased taxpayer expense. However, it is possible that irrigation useincreases under crop insurance. Therefore, there is a need for the explicit consideration of theunintended side effects of crop insurance on farmers’ irrigation water use decisions, particularlyin regions experiencing water scarcity and rising marginal costs of irrigation
Correcting for Linkage Errors in Contingency Tables:A Cautionary Tale
No full textRecord linkage aims to bring records together from two or more files that belong to the same statistical entity. Naïvely treating a linked file as if there are no linkage errors may lead to biased inference. We present two general approaches for compensating for linkage error when calculating and analysing a two-way contingency table for categorical data, and study the following question: under what conditions can a compensation approach improve on the naïve approach, where linkage error is not compensated for? To this end, we compare estimation errors, bias, variance and mean square error for the naïve approach and two compensation approaches by means of an analytical study as well as a simulation study
NOMA and Coded Multicasting in Cache-Aided Wireless Networks
No full textCoded multicasting is considered to be an effectiveapproach to simultaneously serve multiple users in the samefrequency/time/code resource, which is made possible by exploitingthe information available in users’ caches. Recently,non-orthogonal multiple access (NOMA) has emerged as analternative transmission technique for cache-aided network. Incache-aided NOMA system, cache-enabled interference cancellation(CIC) is employed to cancel the interference using theinformation in the cache, and thus enhance the user transmissionrate, particularly for the weak users. Despite the enhancedspectral efficiency offered by both techniques, complexity issuearises from handling large number of users. Therefore, userpairing/clustering should be employed to limit the number ofusers served in the same time-frequency resource. However,the key question is which delivery technique performs betterunder different pairing scenarios. In this paper, the performanceof NOMA and coded multicasting for two-user pairing areinvestigated in terms of probability of sum rate comparison andoutage probability. In order to exploit the benefits of NOMA andcoded multicasting, we also propose a hybrid delivery scheme,which select either NOMA or coded multicasting depending onthe channel conditions of the paired users in each resourceblock (RB). A joint mode selection, power allocation and userpairing scheme is developed to enhance the performance of thehybrid scheme. Both analytical and simulation results demonstratethat NOMA outperforms coded multicasting when pairingusers whose channel gains are highly distinctive, while codedmulticasting is preferred when the paired users have similarchannel gains. In addition, the hybrid scheme is demonstrated tooffer enhanced sum rate performance in comparison to NOMAand coded multicasting
When mortality knocks: Pandemic-inspired attitude shifts towards sustainable clothing consumption in six countries
No full textThis study compares and contrasts consumers’ attitudes towards fashion consumption in different country contexts prior to and during COVID-19, by honing in on their attitude, behavior and relationship with their garments. Issues surrounding sustainable fashion consumption are not new per se (e.g. EEA, 2019; Niniimäki et al., 2020), with consumers’ values, attitudes, and ‘fashion’ consumption practices having been studied in various country contexts (e.g. Lang & Joyner Armstrong, 2018; Iran et al., 2019; Lang et al., 2019). Yet, there has been a noticeable change: the COVID-19 pandemic has disrupted the routine lives of citizens globally, which also had an impact on their fashion consumption practices (e.g. Vogue, 2020; Liu et al., 2021; Youn et al., 2021). This study explores the impacts COVID-19 had on clothing consumption across seven different countries, spanning across the Middle East, Southeast Asia, Europe, and the USA. For this, a survey with open-ended and multiple-choice questions was completed by a sample of consumers (N= 3942) across these countries. Survey participants had an average age of 27.91 and were predominantly female (69%). Initial findings highlight that in Switzerland, Hong Kong, and the UK almost one third of survey respondents changed their attitude towards clothing consumption as a result of the pandemic, which is observed less in the other country contexts. Similar changes in consumers’ relationship with their garments during this time can be observed. Qualitative analysis identified patterns of change in consumers’ attitude toward clothing (e.g. minimalism, grateful mindsets, environmental/social awareness, fashion concerns, style confidence). Identified themes regarding actual behavior included conscious, constrained, stimulated, and safe shopping, casualization of wear, decluttering, and do it yourself. Thus, this paper provides insight into sustainable fashion consumption practices and patterns pre- and during COVID-19, through a multi-country lens.<br/
Statins, Bone Biology and Revision Arthroplasty: Review of Clinical and Experimental Evidence
No full textOsteoarthritis is a painful, disabling condition which is increasing in prevalence as a result of an ageing population. With no recognized disease-limiting therapeutics, arthroplasty of the hip and knee is the most common and effective treatment for lower limb osteoarthritis, however lower limb arthroplasty has a finite life-span and a proportion of patients will require revision arthroplasty. With increasing life expectancy and an increasing proportion of younger (<65 years) patients undergoing arthroplasty, the demand for revision arthroplasty after implant failure is also set to increase. Statins are cholesterol-modulating drugs widely used for cardiovascular risk reduction which have been noted to have pleiotropic effects including potentially influencing arthroplasty survival. In vitro studies have demonstrated pleiotropic effects in human bone cells, including enhancement of osteoblastogenesis following simvastatin exposure, and in vivo studies have demonstrated that intraperitoneal simvastatin can increase peri-implant bone growth in rats following titanium tibial implant insertion. There is evidence that statins may also influence osseointegration, enhancing bone growth at the bone–implant interface, subsequently improving the functional survival of implants. Data from the Danish Hip Arthroplasty Registry and the Clinical Practice Research Datalink in the UK suggest a reduction in the risk of lower limb revision arthroplasty in statin ever-users versus never-users, and a time-dependent effect of statins in reducing the risk of revision. In this article we review the clinical and experimental evidence linking statins and risk of revision arthroplasty.</p
Determining Unilateral or Bilateral Hearing Aid Preference in Adults: A prospective study
No full textObjective: Despite high rates of bilateral hearing aid fitting globally, a number of adults continue to reject one hearing aid. The current study aimed to identify a clinically suitable tool for determining, pre-fitting, which clients might prefer one hearing aid.Design: Ninety-five new adult hearing aid candidates, aged 49 - 87 years, were assessed prior to a first hearing aid fitting. Performance was assessed on a modified version of the Listening in Spatialized Noise – Sentences test (LiSN-S), the Dichotic Digits difference Test, the Experiential Hearing Aid simulator, and the Grooved Pegboard Test. All participants were fitted bilaterally, but were instructed to alternate between unilateral and bilateral hearing aid use over fourteen weeks post-fitting. Participants’ wearing preferences were assessed via a short questionnaire.Study Sample: Sixty-eight participants adhered to the prescribed protocol for both bilateral and unilateral hearing aid use.Results: 78% of participants expressed an overall preference for bilateral hearing aid use. Only the LiSN-S bilateral advantage test outcomes significantly correlated with overall wearing preference.Conclusions: Although the LiSN-S bilateral advantage score related to overall wearing preference, the accuracy of the predictor was too low to warrant implementation of this test prior to hearing aid fitting. The current practice of recommending bilateral hearing aid use continues to be the best option for clinicians
The diagnostic performance of CA125 for the detection of ovarian and non-ovarian cancer in primary care: a population-based cohort study
No full textBackground The serum biomarker Cancer Antigen 125 (CA125) is widely used as an investigation for possible ovarian cancer in symptomatic women presenting to primary care. However, its diagnostic performance in this setting is unknown. We evaluated the performance of CA125 in primary care for the detection of ovarian and non-ovarian cancers. Methods and findings We studied women in the UK Clinical Practice Research Datalink with a CA125 test performed between 1 May 2011 – 31 December 2014. Ovarian and non-ovarian cancers diagnosed in the year following CA125 testing were identified from the cancer registry. Women were categorised by age: <50 years and >50 years. Conventional measures of test diagnostic accuracy, including sensitivity, specificity and positive predictive value, were calculated for the standard CA125 cut-off (≥35 U/ml). The probability of a woman having cancer at each CA125 level between 1-1000 U/ml was estimated using logistic regression. Cancer probability was also estimated on the basis of CA125 level and age in years using logistic regression. We identified CA125 levels equating to a 3% estimated cancer probability: the risk threshold at which the UK National Institute for Health and Care Excellence advocates urgent specialist cancer investigation. 50,780 women underwent CA125 testing; 456 (0.9%) were diagnosed with ovarian cancer and 1321 (2.6%) with non-ovarian cancer. 3.4% of women <50 years and 15.2% of women >50 years with CA125 levels >35 U/ml, had ovarian cancer. 20.4% of women >50 years with a CA125 level >35 U/ml, who did not have ovarian cancer, were diagnosed with a non ovarian cancer. A CA125 value of 53 U/ml equated to a 3% probability of ovarian cancer overall. This varied by age, with a value of 104 U/ml in 40-year-old women and 32 U/ml in 70-year-old women, equating to a 3% probability. The main limitations of our study were that we were unable to determine why CA125 tests were performed and that our findings are based solely on UK primary care data, so caution is need in extrapolating them to other healthcare settings. Conclusions CA125 is a useful test for ovarian cancer detection in primary care, particularly in women >50 years old. Clinicians should also consider non-ovarian cancers in women with high CA125 levels, especially if ovarian cancer has been excluded, in order to prevent diagnostic delay. Our results enable clinicians and patients to determine the estimated probability of ovarian cancer and all cancers at any CA125 level and age, which can be used to guide individual decisions on the need for further investigation or referral