Using optimal foraging theory to infer how groups make collective decisions

A growing body of evidence emerging from the analysis of advanced animal tracking data shows that moving groups make shared decisions about where to go, with each group member influencing the outcome. How groups coordinate departure decisions (when to go), however, remains poorly understood. Classic models from optimal foraging theory, specifically the marginal value theorem (MVT), are well-established tools that can generate quantitative predictions about when individuals should prefer to leave a food patch, given patch quality and the distribution of patches in the environment. Integrating optimal foraging theory into studies of animal collectives provides rich opportunities for gaining new insights from both empirical and theoretical studies. Specifically, the MVT can be used to make predictions about conflict of interests among group members, how consensus costs vary under different models of collective decision-making, and under what environmental conditions shared decision-making may be favored or disfavored

Students’ perceptions of the value of stakeholder engagement during engineering design

BackgroundHuman‐centered design approaches promote and facilitate comprehensive understanding of stakeholders to inform design decisions. Successful engagement with stakeholders is critical to favorable design outcomes and requires skillful information gathering and synthesizing processes, which present unique challenges to student designers.Purpose/HypothesisOur study sought to answer the following research question: What factors influence design teams’ perceptions of the value of stakeholder engagement during design decision‐making?Design/MethodDuring a capstone design experience, we conducted four semistructured group interviews with seven capstone undergraduate student design teams and collected their design reports. We analyzed the data across teams to identify factors that influenced teams’ perceptions of the value of stakeholder engagement.ResultsTeams perceived stakeholder specific interactions to be more useful when they prespecified a goal for the interaction, interacted with stakeholders who had specific subject matter expertise, or ceded control of the decision‐making process to stakeholders. Students perceived interactions to be less useful when information gathered varied across stakeholders or when information was not directly applicable to the design decision at hand.ConclusionsThe factors this study identified that influenced students’ perceptions of the usefulness of stakeholder interactions elucidate specific challenges students encounter when engaging with stakeholders. Students could benefit from pedagogical structures that assist them throughout design‐related engagement with stakeholders and when applying the information gathered through engagements with stakeholders to design decision‐making.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/163394/2/jee20356.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/163394/1/jee20356_am.pd

Beta-blockers to prevent gastroesophageal varices in patients with cirrhosis.

BACKGROUND: Nonselective beta-adrenergic blockers decrease portal pressure and prevent variceal hemorrhage. Their effectiveness in preventing varices is unknown. METHODS: We randomly assigned 213 patients with cirrhosis and portal hypertension (minimal hepatic venous pressure gradient [HVPG] of 6 mm Hg) to receive timolol, a nonselective beta-blocker (108 patients), or placebo (105 patients). The primary end point was the development of gastroesophageal varices or variceal hemorrhage. Endoscopy and HVPG measurements were repeated yearly. RESULTS: During a median follow-up of 54.9 months, the rate of the primary end point did not differ significantly between the timolol group and the placebo group (39 percent and 40 percent, respectively; P=0.89), nor were there significant differences in the rates of ascites, encephalopathy, liver transplantation, or death. Serious adverse events were more common among patients in the timolol group than among those in the placebo group (18 percent vs. 6 percent, P=0.006). Varices developed less frequently among patients with a baseline HVPG of less than 10 mm Hg and among those in whom the HVPG decreased by more than 10 percent at one year and more frequently among those in whom the HVPG increased by more than 10 percent at one year. CONCLUSIONS: Nonselective beta-blockers are ineffective in preventing varices in unselected patients with cirrhosis and portal hypertension and are associated with an increased number of adverse events. (ClinicalTrials.gov number, NCT00006398.

Geometric frustration of hard-disk packings on cones

Conical surfaces pose an interesting challenge to crystal growth: a crystal growing on a cone can wrap around and meet itself at different radii. We use a disk-packing algorithm to investigate how this closure constraint can geometrically frustrate the growth of single crystals on cones with small opening angles. By varying the crystal seed orientation and cone angle, we find that -- except at special commensurate cone angles -- crystals typically form a seam that runs along the axial direction of the cone, while near the tip, a disordered particle packing forms. We show that the onset of disorder results from a finite-size effect that depends strongly on the circumference and not on the seed orientation or cone angle. This finite-size effect occurs also on cylinders, and we present evidence that on both cylinders and cones, the defect density increases exponentially as circumference decreases. We introduce a simple model for particle attachment at the seam that explains the dependence on the circumference. Our findings suggest that the growth of single crystals can become frustrated even very far from the tip when the cone has a small opening angle. These results may provide insights into the observed geometry of conical crystals in biological and materials applications.Comment: 12 pages, 13 figure

Evolution of the eyes of vipers with and without infrared-sensing pit organs

We examined lens and brille transmittance, photoreceptors, visual pigments, and visual opsin gene sequences of viperid snakes with and without infrared-sensing pit organs. Ocular media transmittance is high in both groups. Contrary to previous reports, small as well as large single cones occur in pit vipers. Non-pit vipers differ from pit vipers in having a twotiered retina, but few taxa have been examined for this poorly understood feature. All vipers sampled express rh1, sws1 and lws visual opsin genes. Opsin spectral tuning varies but not in accordance with the presence/absence of pit organs, and not always as predicted from gene sequences. The visual opsin genes were generally under purifying selection, with positive selection at spectral tuning amino acids in RH1 and SWS1 opsins, and at retinal pocket stabilization sites in RH1 or LWS (and without substantial differences between pit and nonpit vipers). Lack of evidence for sensory trade-off between viperid eyes (in the aspects examined) and pit organs might be explained by the high degree of neural integration of vision and infrared detection; the latter representing an elaboration of an existing sense with addition of a novel sense organ, rather than involving the evolution of a wholly novel sensory system

Structural analysis of the starfish SALMFamide neuropeptides S1 and S2: The N-terminal region of S2 facilitates self-association

The neuropeptides S1 (GFNSALMFamide) and S2 (SGPYSFNSGLTFamide), which share sequence similarity, were discovered in the starfish Asterias rubens and are prototypical members of the SALMFamide family of neuropeptides in echinoderms. SALMFamide neuropeptides act as muscle relaxants and both S1 and S2 cause relaxation of cardiac stomach and tube foot preparations in vitro but S2 is an order of magnitude more potent than S1. Here we investigated a structural basis for this difference in potency using spectroscopic techniques. Circular dichroism spectroscopy showed that S1 does not have a defined structure in aqueous solution and this was supported by 2D nuclear magnetic resonance experiments. In contrast, we found that S2 has a well-defined conformation in aqueous solution. However, the conformation of S2 was concentration dependent, with increasing concentration inducing a transition from an unstructured to a structured conformation. Interestingly, this property of S2 was not observed in an N-terminally truncated analogue of S2 (short S2 or SS2; SFNSGLTFamide). Collectively, the data obtained indicate that the N-terminal region of S2 facilitates peptide self-association at high concentrations, which may have relevance to the biosynthesis and/or bioactivity of S2 in vivo

Pengendalian Waktu Dan Biaya Pada Tahap Pelaksanaan Proyek Dengan Menggunakan Metode Nilai Hasil (Studi Kasus : Proyek Lanjutan Pembangunan Gedung Pip2b Kota Manado)

Pengendalian dalam proyek konstruksi pada umumnya menyangkut tiga aspek utama, yaitu, biaya, waktu dan SDM. Didalam pelaksanaan suatu proyek konstruksi, perencanaan dan pengendalian merupakan fungsi yang paling pokok didalam mewujudkan keberhasilan proyek. Persoalan yang timbul adalah bagaimana mencapai pemecahan optimum dengan kondisi sumber daya yang serba terbatas. Bagaimana menerapkan suatu metode pada proyek untuk mengendalikan biaya dan waktu, serta mengendalikan pelaksanaan proyek konstruksi terhadap terjadinya penyimpangan, dan mengevaluasi proyeksi penyelesaian terhadap terjadinya penyimpangan pada proyek merupakan tujuan dari penelitian ini. Untuk meningkatkan efektivitas dalam memantau dan mengendalikan proyek, perlu dipakai metode yang mengintegrasikan jadwal dan biaya sehingga mengungkapkan kinerja kegiatan. Salah satu metode yang memenuhi tujuan ini adalah Konsep Nilai Hasil, Earned Value Concept, yang terdiri dari tiga indikator yaitu BCWS, BCWP, dan ACWP. Prosedur penelitian dimulai dengan melakukan studi kepustakaan, pengambilan data, melakukan pengamatan langsung pada proyek, dan merangkum hasil pengumpulan data-data yang ada. Variansi yang ditekankan disini adalah untuk menyelidiki penyimpangan biaya atau jadwal pelaksanaan yang telah direncanakan atau ditentukan. Bila angka kinerja ditinjau lebih lanjut maka Angka indeks kinerja kurang dari satu (1) yang berarti makin besar penyimpangannya dari perencanaan dasar atau anggaran, atau prestasi pelaksanaan pekerjaan sangat baik, perlu diadakan pengkajian apakah mungkin perencanaan tidak realistis. Konsep Nilai Hasil bisa diterapkan pada studi kasus ini di dalam tujuan pengendalian dimana berdasarkan analisis maka pengendalian yang dilakukan banyak terjadi penyimpangan dari sisi penjadwalan pada saat pelaporan-pelaporannya. Berdasarkan nilai ETC dan EAC yang terhitung maka apabila kinerja tidak diperbaharui akan terjadi bergeseran

Alterations to the Gastrointestinal Microbiome Associated with Methamphetamine Use among Young Men who have Sex with Men.

Methamphetamine (MA) use is a major public health problem in the United States, especially among people living with HIV (PLWH). Many MA-induced neurotoxic effects are mediated by inflammation and gut microbiota may play a role in this process, yet the effects of MA on the microbiome have not been adequately explored. Therefore, we performed 16S rRNA gene sequencing on rectal swab samples from 381 men who have sex with men, 48% of whom were PLWH and 41% of whom used MA. We compared microbiome composition between MA users and non-users while testing for potential interactions with HIV and controlling for numerous confounders using inverse probability of treatment weighting. We found that MA use explained significant variation in overall composition (R2 = 0.005, p = 0.008) and was associated with elevated Finegoldia, Parvimonas, Peptoniphilus, and Porphyromonas and reduced Butyricicoccus and Faecalibacterium, among others. Genera including Actinomyces and Streptobacillus interacted with HIV status, such that they were increased in HIV+ MA users. Finegoldia and Peptoniphilus increased with increasing frequency of MA use, among others. In summary, MA use was associated with a microbial imbalance favoring pro-inflammatory bacteria, including some with neuroactive potential and others that have previously been associated with poor HIV outcomes

The Effects of Virtual Reality on the Upper Extremity Skills of Girls with Rett Syndrome: A Single Case Study

Introduction: Rett Syndrome (RTT) is a genetic disorder primarily seen in females that inhibits the use of a girl's hands in everyday activities. A girl with RTT spends the majority of her day engaged in stereotypical hand wringing/mouthing movements at midline of the body. The probable cause behind the neurological effects of RTT is a mutation in the gene that encodes for methyl-CpG protein 2 (MeCP2). The hand wringing/mouthing behaviors preclude a girl with RTT from using the upper extremities in purposeful tasks such as school work, play skills, and other activities of daily living.Objectives: To develop a virtual reality (VR)-based therapeutic intervention that 1) decreases upper extremity stereotypies (repetitive movements that serve no function) that interfere with purposeful arm and hand use and 2) promotes purposeful, goal-directed arm function; improve upper extremity motor skills in girls with RTT.Materials and Methods: Using FAAST Software and Microsoft Kinect sensor, one girl with RTT participated in a 12-week IVR intervention (1 hour/session, 3 sessions/week, 36 total hours). Pre- and post-assessments were administered to examine any changes in upper extremity function.Results: The VR intervention led to improvements in use of the upper extremities to complete self-care activities, an increased number of reaches completed in a 15-minute period, and decreased time engaged in stereotypical hand movements.Conclusion: Future work will add additional support to determine the effectiveness of virtual reality as an intervention for girls with RTT