A New General-Purpose Algorithm for Mixed-Integer Bilevel Linear Programs

Bilevel optimization problems are very challenging optimization models arising in many important practical contexts, including pricing mechanisms in the energy sector, airline and telecommunication industry, transportation networks, critical infrastructure defense, and machine learning. In this paper, we consider bilevel programs with continuous and discrete variables at both levels, with linear objectives and constraints (continuous upper level variables, if any, must not appear in the lower level problem). We propose a general-purpose branch-and-cut exact solution method based on several new classes of valid inequalities, which also exploits a very effective bilevel-specific preprocessing procedure. An extensive computational study is presented to evaluate the performance of various solution methods on a common testbed of more than 800 instances from the literature and 60 randomly generated instances. Our new algorithm consistently outperforms (often by a large margin) alternative state-of-the-art methods from the literature, including methods exploiting problem-specific information for special instance classes. In particular, it solves to optimality more than 300 previously unsolved instances from the literature. To foster research on this challenging topic, our solver is made publicly available online

Exact algorithms for the 0–1 Time-Bomb Knapsack Problem

We consider a stochastic version of the 0–1 Knapsack Problem in which, in addition to profit and weight, each item is associated with a probability of exploding and destroying all the contents of the knapsack. The objective is to maximise the expected profit of the selected items. The resulting problem, denoted as 0–1 Time-Bomb Knapsack Problem (01-TB-KP), has applications in logistics and cloud computing scheduling. We introduce a nonlinear mathematical formulation of the problem, study its computational complexity, and propose techniques to derive upper and lower bounds using convex optimisation and integer linear programming. We present three exact approaches based on enumeration, branch and bound, and dynamic programming, and computationally evaluate their performance on a large set of benchmark instances. The computational analysis shows that the proposed methods outperform the direct application of nonlinear solvers on the mathematical model, and provide high quality solutions in a limited amount of time

A disposable amperometric biosensor for rapid screening of anticholinesterase activity in soil extracts

A disposable amperometric biosensor for the determination of anticholinesterase activity in soil extracts is described. The sensitive membrane was obtained by co-crosslinking acetylcholinesterase and choline oxidase with bovine serum albumin using glutaraldehyde. The anticholinesterase activity of the soil extract was measured using chronoamperometry at 650 mV vs. Ag/AgCl to monitor the biocatalytically produced H2O2 before and after the inhibition step. An inhibition percentage of 38 ± 4% was recorded for soil extracts spiked with 10 ppb of ethyl parathion. The device has the potential to be used as a gross sensor for the assessment of anticholinesterase activity in soil extracts

Estimating the net return of a remote calving alarm system in a dairy farm

The aim of the study was to evaluate the net return of the implementation of a remote calving monitoring system for obstetrical and neonatal assistance on the herd economy in a dairy farm model. A total of 680 parturitions over a 7-yr period were evaluated. Age at first calving was restricted from 23 to 27 mo for primiparous cows to be included. Among groups of cows that were ready to calve in a 15-d interval, primiparous and multiparous were randomly assigned to the experimental group and monitored through a calving alarm system, whereas the others accounted for controls. Final parturition groups were as follows: control primiparous (CPP, n = 218), control multiparous (CM, n = 345), monitored primiparous (MPP, n = 56), and monitored multiparous (MM, n = 61). Monitored groups received prompt calving assistance and first neonatal care, whereas the presence of farm personnel was discontinuous for controls. A biological model was built considering significant differences in calf loss, early culling, milk production, and days open between groups. Then, a partial budget model was used to estimate costs and net return on a simulated herd of 100 lactating cows. Incidence of calf death was greater in control groups (11.06% and 10.73% in CPP and CM, respectively) compared with monitored cows (0.00% and 1.69% in MPP and MM, respectively). Multiparous cows with calf loss had increased relative risk (relative risk = 3.487) for early culling compared with multiparous counterparts with no neonatal loss. Daily milk production in the first 2 mo was 3.79 kg greater in multiparous cows with no dead calf, compared with their counterparts. A significant difference in median days open was found in MPP and CPP (118 and 148 d, respectively). In the final economic model, different simulations were analyzed. They were created assuming different prices or hypothesizing calving monitoring only in primiparous animals. The model estimated different, but always positive, net return. In conclusion, implementing a calving alarm system led to a net return from \u20ac37 to 90 per cow per year (\u20ac1 = US$1.15 at the time of the study). However, the device alone is not sufficient: it must be supported by qualified calving monitoring and assistance. Optimized personnel presence in the calving area at the right time leads to prompt calving and neonatal calf assistance and colostrum feeding within the first hours of life, thus reducing calf death and days open, and increasing milk production

Emotion regulation and desire thinking as predictors of problematic Facebook use

Background: Research evidence suggests that problematic Facebook use (PFU) affects large numbers of people worldwide. A variety of studies have investigated the relationship between PFU and psychological dysfunction, revealing that negative mood and cognitive self-regulation are common among problematic Facebook users. Aim: The aim of the present study was to examine the role of craving, emotion regulation and desire thinking in predicting PFU. Methods: An online survey was administered to 750 participants (males = 82%; Mage = 23.38 years; SDage = 5.72). Correlation analyses were conducted in order to test the associations between emotion regulation, craving, desire thinking and PFU. A path analysis was run to model the inter-relationships between the variables based on previous research findings. Results: Correlation analyses indicated that all predictor variables were positively associated with PFU. Path analysis showed that imaginal prefiguration was associated with craving, which, in turn, was associated with verbal prefiguration that was directly linked to PFU, beyond the direct effect of emotion regulation. Conclusions: These findings provide further support for the importance of desire thinking in predicting problematic behaviours. Desire thinking and emotion regulation should be considered in the modification of problematic Facebook use

Laparotomic intrauterine insemination with frozen-thawed semen in Sopravissana breed ewes in Central Italy

Intrauterine laparoscopic insemination is diffuse in sheep breeding, yet requires veterinary expertise and expensive equipment. Our aim was to evaluate the time required, reproductive outcome and post-operative complications of mini invasive laparotomic intrauterine insemination, as an alternative approach to laparoscopy. A total of 115 Sopravvissana breed ewes were enrolled, including 75 adults and 40 lamb ewes, after oestrus synchronisation. Ewes were sedated and restrained in dorsal recumbence. Uterine horns were exposed through an abdominal incision of 4\u20137 cm, cranially to the udder. Thawed semen, containing 100 7 106 progressive motile (70%) and morphologically normal (80%) sperm cells, was inoculated into uterine lumen through an intravenous catheter. The abdominal incision was then routinely closed. The time interval for: (a) laparotomy and uterine exteriorisation, (b) intrauterine insemination, (c) abdominal wall closure and (d) total procedure was recorded. Pregnancy, lambing, twinning rates and sex ratio were submitted to chi-square test, comparing lamb and adult ewes. Time intervals and the duration of laparotomic procedure were compared in lamb and adults through Mann\u2013Whitney U test for independent samples. Median \ub1 standard error (SE) of total time for laparotomic intrauterine insemination was 5.53 \ub1 0.07 and 4.99 \ub1 0.11 min, for adult and lamb ewes (p<.05), which was similar to what was reported for laparoscopic methods. At pregnancy check, 60% and 70% of adult and lamb ewes resulted pregnant. Laparotomy is poorly applied due to risk of adherence and decreased fertility. In our study, ewes were naturally bred in the following season with 90% pregnancy rate. Our results showed that time for laparotomy is quite similar to laparoscopic insemination, as for the conception and lambing rates.HIGHLIGHTS Time required for the overall procedure (5.53 \ub1 0.07 and 4.99 \ub1 0.11 min, for adult and lamb ewes, respectively, with significant difference (p<.05)) was similar to laparoscopic artificial insemination. About 60% and 70% of adult and lamb ewes resulted pregnant, respectively. No decreased fertility was observed in the following breeding season (90% pregnancy rate at natural insemination). Laparotomic approach is quite similar to laparoscopic insemination, in terms of time required for its complete achievement, for the conception and lambing rates; furthermore it has the advantage of reducing equipment costs

Environmental Factors Affecting the Reproductive Efficiency of Italian Simmental Young Bulls

The objectives of the study aimed to evaluate the effect of weather conditions and scrotal circumference (SC) on standard semen characteristics of Italian Simmental young bulls (n = 577), all raised in the same performance station and sampled by the artificial vagina (AV) method. Considering the increasing SC, the results showed a significant increase in quantitative semen parameters (p < 0.05 and p < 0.0001, for sperm concentration and total number of spermatozoa, respectively); for every extra centimeter of SC, 17.5 × 106 spermatozoa/mL and 0.102 × 109 of total spermatozoa were produced. The age of the animal at semen collection (395 and 465 days) had similar positive effects. The effect of the average temperature humidity index (THI limits ≤ 40 and ≥70) in the previous 60, 30, and 10 days before the semen collection was also considered. Sixty days before the semen collection, the increasing THI increased both primary (p < 0.0001) and secondary (p < 0.0001) abnormalities while the percentage of morphologically normal spermatozoa decreased (p < 0.0001). Thirty and ten days before collection, the same effect on morphological traits was maintained, but total and progressive motility was also influenced (p < 0.01) with an unexpected increasing pattern. Thus, environmental conditions can influence semen quality during the entire spermatogenesis and results can guide future research on this breed

Music Teacher Education at a Liberal Arts College

In 2012, a committee at a small Midwestern liberal arts college, Lake Forest College, embarked on a journey to create a music education teacher licensure major. Drawing from narrative inquiry, this article reports how the dean of faculty, education department chair, music department chair, and assistant professor of music/music education coordinator collaborated on a curricular creation. Findings from this process included (a) the created music education major, (b) each participant’s rationale for wanting the new music education major, (c) valued components of the music education major, and (d) unique elements of a music education major at a liberal arts college. Implications from this experience could be valuable for music education programs at small liberal arts colleges, those involved in university/school partnerships such as professional development schools, and those looking to advocate for their music education programs across campus