Directional persistence & the optimality of run-and-tumble chemotaxis

E. coli does chemotaxis by performing a biased random walk composed of alternating periods of swimming (runs) and reorientations (tumbles). Tumbles are typically modelled as complete directional randomisations but it is known that in wild type E. coli, successive run directions are actually weakly correlated, with a mean directional difference of not, vert, similar63°. We recently presented a model of the evolution of chemotactic swimming strategies in bacteria which is able to quantitatively reproduce the emergence of this correlation. The agreement between model and experiments suggests that directional persistence may serve some function, a hypothesis supported by the results of an earlier model. Here we investigate the effect of persistence on chemotactic efficiency, using a spatial Monte Carlo model of bacterial swimming in a gradient, combined with simulations of natural selection based on chemotactic efficiency. A direct search of the parameter space reveals two attractant gradient regimes, (a) a low-gradient regime, in which efficiency is unaffected by directional persistence and (b) a high-gradient regime, in which persistence can improve chemotactic efficiency. The value of the persistence parameter that maximises this effect corresponds very closely with the value observed experimentally. This result is matched by independent simulations of the evolution of directional memory in a population of model bacteria, which also predict the emergence of persistence in high-gradient conditions. The relationship between optimality and persistence in different environments may reflect a universal property of random-walk foraging algorithms, which must strike a compromise between two competing aims: exploration and exploitation. We also present a new graphical way to generally illustrate the evolution of a particular trait in a population, in terms of variations in an evolvable parameter

The Grizzly, September 23, 1983

Security Measures Enacted • Rape Suspect Arrested • Union Welcomes Director • President\u27s Corner • Letters to the Editor • What to do With Your First $10,000 • Art Exhibit Opens • French Professor Earns Doctorate • Bloodmobile is Back • The New Invasion • Some People Never Give Up • Math, Science Teachers Needed • Ursinus Welcomes New Faculty • Calling All Diabetics: Wanna be a Guinea Pig? • New Look Bears Score Grid Upset • Field Hockey Off to Fine Start • Seniors Anchor U.C. Soccer • Sports Profilehttps://digitalcommons.ursinus.edu/grizzlynews/1101/thumbnail.jp

Considerations on implementation of the newest treatment for symptomatic uterine fibroids : oral GnRH antagonists

Peer reviewe

The Grizzly, October 28, 1983

CampusBooks Speaks Out • C and C Course Offered • Zack Is Back In Bronze • Peace Rally Held • Give Us A Little Bit Of Credit • Respect Is Goal Of Liberal Education • Homecoming: A Big Success • Nobel Prize Awarded • Spirit Week Begins • The Talented Two-Some • The Stone Age is Back • Crown Royal Features Ultimate Competition • Lady Bears Prepare For Penn State Rivalry • U.C. Soccer Continues Winning Ways • Grizziles Roll Over Lebanon Valleyhttps://digitalcommons.ursinus.edu/grizzlynews/1105/thumbnail.jp

Exposure to Weight Management Counseling Among Students at 8 U.S. Medical Schools

INTRODUCTION: Clinical guidelines support physician intervention consistent with the Ask, Advise, Assess, Assist, Arrange framework for adults who have obesity. However, weight management counseling curricula vary across medical schools. It is unknown how frequently students receive experiences in weight management counseling, such as instruction, observation, and direct experience. METHODS: A cross-sectional survey, conducted in 2017, of 730 third-year medical students in 8 U.S. medical schools assessed the frequency of direct patient, observational, and instructional weight management counseling experiences that were reported as summed scores with a range of 018. Analysis was completed in 2017. RESULTS: Students reported the least experience with receiving instruction (6.5, SD=3.9), followed by direct patient experience (8.6, SD=4.8) and observational experiences (10.3, SD=5.0). During the preclinical years, 79% of students reported a total of \u3c /=3 hours of combined weight management counseling instruction in the classroom, clinic, doctor\u27s office, or hospital. The majority of the students (59%-76%) reported never receiving skills-based instruction for weight management counseling. Of the Ask, Advise, Assess, Assist, Arrange framework, scores were lowest for assisting the patient to achieve their agreed-upon goals (31%) and arranging follow-up contact (22%). CONCLUSIONS: Overall exposure to weight management counseling was less than optimal. Medical school educators can work toward developing a more coordinated approach to weight management counseling. Inc

The Grizzly, September 30, 1983

Fraternities Speak Out • Media Meeting Held • Forum Series Begins • President\u27s Corner • Letters to the Editor • Student Profile: Weible on Wheels • Guitarist Plays at Ursinus • Faculty Lectures Open • Everybody\u27s Rockin\u27 • Accountants Sponsor Competition • Parsons Stars in Video • Volleyball Picks up First Win • Gone But Not Forgotten • Speech Exemption Exam to be Given • Soccer Team Seeks to Regroup for Divisional Play • Hockey Lookin\u27 Good • Bear Pack up for Strong Season • Western Maryland Bombs Bearshttps://digitalcommons.ursinus.edu/grizzlynews/1102/thumbnail.jp

Whole Genome Sequencing Shows a Low Proportion of Tuberculosis Disease Is Attributable to Known Close Contacts in Rural Malawi.

BACKGROUND: The proportion of tuberculosis attributable to transmission from close contacts is not well known. Comparison of the genome of strains from index patients and prior contacts allows transmission to be confirmed or excluded. METHODS: In Karonga District, Malawi, all tuberculosis patients are asked about prior contact with others with tuberculosis. All available strains from culture-positive patients were sequenced. Up to 10 single nucleotide polymorphisms between index patients and their prior contacts were allowed for confirmation, and ≥ 100 for exclusion. The population attributable fraction was estimated from the proportion of confirmed transmissions and the proportion of patients with contacts. RESULTS: From 1997-2010 there were 1907 new culture-confirmed tuberculosis patients, of whom 32% reported at least one family contact and an additional 11% had at least one other contact; 60% of contacts had smear-positive disease. Among case-contact pairs with sequences available, transmission was confirmed from 38% (62/163) smear-positive prior contacts and 0/17 smear-negative prior contacts. Confirmed transmission was more common in those related to the prior contact (42.4%, 56/132) than in non-relatives (19.4%, 6/31, p = 0.02), and in those with more intense contact, to younger index cases, and in more recent years. The proportion of tuberculosis attributable to known contacts was estimated to be 9.4% overall. CONCLUSIONS: In this population known contacts only explained a small proportion of tuberculosis cases. Even those with a prior family contact with smear positive tuberculosis were more likely to have acquired their infection elsewhere

The Grizzly, November 11, 1983

Tuition Hike OK\u27ed • Founder\u27s Day Celebrated • On the Air Finally • Ursinus Commemorated on Founder\u27s Day • Letters To The Editor: Credit Policy Reviewed; Coach Needed for Diving Team; No Credit for Activities • Smart People, Poor Students • Writing Help Available • Like Father, Like Son • Choir Goes German • Two Free Plays At Ursinus • The Big Event: Casino Night Comes to Ursinus • And Another Thing • Lady Bears ECAC Champs • U.C. Soccer Hosts ECAC Tourney • Grizzlies Bury Brooklyn College • Ursinus Fourth • Women\u27s Field Hockey Concludes Successful Campaignhttps://digitalcommons.ursinus.edu/grizzlynews/1107/thumbnail.jp

Romantic jealousy and relationship satisfaction: the costs of rumination

The experience of romantic jealousy and its influence on relationship outcomes is unclear. Romantic jealousy is often associated with damaging effects; on the other hand, jealousy is linked to positive relationship outcomes such as increased commitment. In this study, we aimed to address inconsistencies in previous research by proposing rumination as a mediator between romantic jealousy (cognitive jealousy and surveillance behaviors) and relationship dissatisfaction. We also aimed to extend our understanding of behavioral responses to jealousy, and in particular, partner surveillance and its link to relational dissatisfaction by proposing a research question. Overall, there were two paths to relationship dissatisfaction: Cognitive jealousy and surveillance behaviors were associated with relationship dissatisfaction via rumination, and cognitive jealousy was also directly associated with relationship dissatisfaction. Interestingly, surveillance behaviors were directly associated with relationship satisfaction. From these results, rumination is highlighted as a factor in explaining the link between romantic jealousy and relationship dissatisfaction. Clinical implications are discussed

Planning for Sustainability in Small Municipalities: The Influence of Interest Groups, Growth Patterns, and Institutional Characteristics

How and why small municipalities promote sustainability through planning efforts is poorly understood. We analyzed ordinances in 451 Maine municipalities and tested theories of policy adoption using regression analysis.We found that smaller communities do adopt programs that contribute to sustainability relevant to their scale and context. In line with the political market theory, we found that municipalities with strong environmental interests, higher growth, and more formal governments were more likely to adopt these policies. Consideration of context and capacity in planning for sustainability will help planners better identify and benefit from collaboration, training, and outreach opportunities