A winner determination problem of tendering transportation services

Summary  For the tendering of long-term transportation contracts in the bulk industry, shippers use bidbooks that specify for each lane the load location, the destination, the product and the volume that has to be transported over the next so many years. Bidbooks are sent out to a preselected group of carriers, who subsequently quote a price for each of the lanes. After the return of the bidbooks, the shipper determines the winning carriers. The winner determination problem is the problem of finding an allocation of the lanes to the carriers so as to minimize total transportation costs. The winner determination problem is NP-hard in the strong sense. We model the winner determination problem as an integer linear programming (ILP) problem and try and solve the model by use of CPLEX, a state-of-the-art ILP solver. It turns out, that the model can solve problems optimally with no more than 270 lanes. We also develop a fast randomized heuristic, and we show that it performs remarkably well, with a gap of no more than 0.8% from optimality.

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Zusammenfassung  Zum Abschluss langfristiger Transportvertr?ge in der Massengüterindustrie bedienen sich die Spediteure bestimmter Angebotsbücher, in denen für jede Tour die Ladestation, der Zielort, sowie die zu transportierende Produktart und deren Volumen für die n?chsten Jahre spezifiziert werden. Die Angebotsbücher werden an eine ausgew?hlte Gruppe von Transportunternehmen geschickt, die dann für jede Tour einen Preis angeben. Auf dieser Grundlage bestimmt der Spediteur dann die Transportunternehmen, die die Zuteilung der Touren erhalten. Dabei wird die Verteilung der Touren auf die Transportunternehmen in der Weise vorgenommen, dass die gesamten Transportkosten minimiert werden. Das Auswahlproblem ist NP-hard in strengem Sinne. Wir modellieren das Auswahlproblem als ganzzahliges lineares Programmierungsproblem (ILP) und testen bzw. l?sen es mit Hilfe mit CPLEX, einem Standardl?sungsansatz für ganzzahlige lineare Programmierung. Dabei zeigt sich, dass Modelle bis zu 270 Touren optimal gel?st werden k?nnen. Zugleich wird auch eine Heuristik entwickelt und vorgestellt, deren L?sung nur unwesentlich von der Optimall?sung entfernt liegt.

     

Healthcare providers' treatment of college smokers

About 28% of college students smoke tobacco, and many will continue smoking into adulthood. Although little is known about how to help college students quit smoking, 1 promising strategy is healthcare providers' advice. To estimate their life-time receipt of brief advice and to identify characteristics that predict who may receive that advice, 348 college students completed a survey about their smoking and related practices. Seventy-seven percent of the smokers (73% of the students) were asked about smoking. Of those smokers, 57% were advised to quit, 22% were given advice about quitting, 5% were helped with setting a quit date, and 4% were offered follow-up. Occasional smokers were less likely than daily smokers to be advised to quit. Although 36.2% of the smokers did not report their smoking accurately, smokers who were accurate were more likely to be advised to quit and to be given advice about quitting.     

Implementation and results of the statewide ONHRSS

In response to increased consumer demand, state governments are publishing more detailed information about the quality of nursing homes. In 2002, Ohio legislation mandated the publication of a Long-Term Care Consumer Guide that included information on nursing home resident and family satisfaction surveys. Using the 2002 Ohio Nursing Home Resident Satisfaction Survey as an example, this article addresses two research questions: (1) how can statewide resident face-to-face satisfaction interviews be implemented to maximize participation of residents and facilities and produce reliable and valid results, and (2) how satisfied are residents with their nursing home experiences, overall and by level of cognitive function.     

Non-estrogen-based treatments for menopausal symptoms

The British Menopause Society Council is committed to provide up-to-date authoritative reviews to aid health professionals to inform and advise women about key issues in postreproductive health. This guidance refers to non-estrogen-based treatments for menopausal symptoms, such as hot flushes, symptoms of urogenital atrophy and lack of sexual desire. Treatment of choice should be based on up to-date information and targeted to individual women's needs. Non-hormonal strategies may be useful for women with estrogen-dependent disease such as breast cancer.     

High-risk sexual behavior among students of a minority-serving university in a community with a high HIV/AIDS prevalence

OBJECTIVE: The authors used a stratified cluster sampling design to inform campus sexually transmitted diseases prevention programs. PARTICIPANTS AND METHODS: They conducted a cross-sectional study of students (N = 1,130) at a large, urban, minority-serving university in South Florida using the 2004 National College Health Assessment Survey instrument. RESULTS: Of the 1,130 participants, 14.0% reported risky sexual behavior (having more than 1 sexual partner in 1 year and not using a condom the last time they had vaginal intercourse), and 11.9% reported consistent risky sexual behavior (having more than 1 partner in 1 year and not using condoms most or all of the time during the past 30 days). In multivariable analysis, past-month alcohol use had the strongest independent association with both risky and consistent risky sexual behavior. Illicit drug use was marginally significant in both models. CONCLUSIONS: Administrators should address the use of alcohol and other drugs on campus in planning interventions to promote safe sexual behavior.     

An analysis pipeline for estimating true intake from repeated measurements with random errors

The accurate estimation of an individual's usual dietary intake is an important topic in nutritional epidemiology. This paper considers the best linear unbiased predictor (BLUP) computed from repeatedly measured dietary data and derives several nonparametric prediction intervals for true intake. However, the performance of the BLUP and the validity of prediction intervals depends on whether required model assumptions for the true intake estimation problem hold. To address this issue, the paper examines how the BLUP and prediction intervals behave in the case of a violation of model assumptions, and then proposes an analysis pipeline for checking them with data.     

“…It’s Just Very Hard To Fail A Student…”: Decision-Making And Defences Against Anxiety – An Ethnographic And Practice-Near Study Of Practice Assessment Panels

The practice learning site is an important place of determining suitability for social work practice and as such is a key site of gate keeping. Research, both international and multi-disciplinary have consistently highlighted the challenging emotional processes involved in failing a student in a practice learning setting. This research has largely focused on practice educators. What has been not been explored however, are wider decision-making processes about students who have failed the placement, namely, what is known in the UK as the Practice Assessment Panel (PAP). The paper thus documents findings from an ethnographic study of four PAPs in England, utilising a practice-near analytical approach. Findings centre around three key themes; the deferring of difficult decisions, powerful voices and the unacknowledged emotional climate. The paper concludes that the PAP can be theorised as a powerful projective field and suggests possible ways forward in light of the themes to emerge.     

Limits of Object Persistence: Young Infants Perceive Continuity of Vertical and Horizontal Trajectories,But Not 45‐Degree Oblique Trajectories

Previous research indicated that 4‐month‐old infants perceive continuity of objects moving on horizontal trajectories but appear to have difficulty processing occlusion events involving oblique trajectories. However, because perception of continuity of vertical trajectories has not been tested, it is uncertain whether this indicates a specific deficit for oblique trajectories or a specific advantage for horizontal trajectories. We evaluated the contribution of trajectory orientation and the form of occlusion in three experiments with one hundred and forty‐four 4‐month‐olds. Infants perceived continuity of horizontal and vertical trajectories under all conditions presented. However, they did not perceive continuity of an oblique (45°) trajectory under any condition. Thus, 4‐month‐olds appear unable to process continuity of a 45° trajectory. In a fourth experiment with forty‐eight 6‐ and 8‐month‐old infants, we demonstrated that by 6 months, infants' difficulty with oblique trajectories is overcome. We suggest that young infants' difficulty with markedly oblique trajectories likely relates to immature eye movement control.     

Shaping emotional reactions to ethical behaviors: Proactive personality as a substitute for ethical leadership

Due to ethical lapses of leaders, interest in ethical leadership has grown, raising important questions about the responsibility of leaders in ensuring moral and ethical conduct. However, research on ethical leadership has failed to examine the active role that followers' attributes play in enhancing or minimizing the influence of ethical leadership in organizational outcomes. We applied the substitutes for leadership approach (Kerr & Jermier, 1978) to ethical leadership and predicted that proactive personality acts as substitute in the relationship between ethical leadership, workplace emotions and organizational citizenship behaviors (OCBs). Data from two distinct samples offered strong support for the hypotheses. Specifically, we found that ethical leadership was significantly and negatively related to negative workplace emotions when subordinate proactive personality was low, but not when it was high, with consequences for OCBs. These findings suggest that proactive personality constitutes an important moderator on the impact of low ethical leadership on workplace emotions, with consequences for OCBs.