Freely forming groups: trying to be rare

A simple weakly frequency dependent model for the dynamics of a population with a finite number of types is proposed, based upon an advantage of being rare. In the infinite population limit, this model gives rise to a non-smooth dynamical system that reaches its globally stable equilibrium in finite time. This dynamical system is sufficiently simple to permit an explicit solution, built piecewise from solutions of the logistic equation in continuous time. It displays an interesting tree-like structure of coalescing components

The measurement of residual feed intake to determine feed efficiency of pregnant Hereford heifers

Abstract only availableThe large potential improvement in profitability is what makes feed efficiency such a studied and concerned topic in the beef industry today. Currently, no herd exists in the United States that has been selected solely for the purpose of measuring and improving feed efficiency. The objective of this study was to rank forty-two pregnant Hereford heifers based on their feed efficiencies, so that they may be mated to bulls of known efficiency. The long term goal of this project is to create both efficient and inefficient herds for future feed efficiency research. These heifers were acquired from various beef producers across the state to ensure genetic variation within the herd. The heifers were fed an alfalfa/grass hay to which they had ad libitum access. Their diet was 86% dry matter and contained 58% neutral detergent fiber, 38% acid detergent fiber, and 14% crude protein on a dry matter basis. The individual intake of each heifer was recorded by the GrowSafe® feed intake system. Expected feed intake was calculated as a regression of actual intake on average daily gain and metabolic mid-weight. Expected feed intake was subtracted from actual feed intake to calculate the residual feed intake value of each individual heifer. Residual feed intake was then used as a measure of feed efficiency. The average body weight at the start of the study was 488 kg. Heifers consumed on average 17.77 ± 5.24 kg/d, and the herd gained at a rate of 0.77 ± 0.32 kg/d. The most efficient heifer consumed 9.78 kg/d less than was expected, while the most inefficient heifer consumed 11.54 kg/d more than was expected. Calculating residual feed intake as a means of determining feed efficiency will enable us to establish both efficient and inefficient herds for further research.F.B. Miller Undergraduate Research Program in Animal Science

Greater numbers and sizes of muscle bundles in the breast and leg muscles of broilers compared to layer chickens

Meat-type (broiler) and egg-type (layer) chickens were bred by intensive selection over the years, resulting in more numbers and larger sizes of myofibers. Although the characteristics are important parameters in muscle growth and meat quality, muscle bundle characteristics have not been studied in poultry. Therefore, this study aimed to compare the histological characteristics of myofibers and muscle bundles in muscles between male broiler (Ross broiler breed) chickens and layer (Hy-Line) chickens. Chicken muscles, pectoralis major (PM) and gastrocnemius (GM), were sampled at the age of 49 days and stained to analyze histological characteristics. Expectedly, body weights (BWs) and weights of PM and GM muscles in 49-day-old broilers were significantly heavier than those in layers. Within PM, broilers exhibited greater number and cross-sectional area (CSA) of myofibers than layers (3.3- and 3.3-fold, respectively). The total number and CSA of PM muscle bundles were approximately 1.5 and 6.6 times greater, respectively, in broilers than layers. Moreover, broilers exhibited 2 times greater number of myofibers per bundle of PM muscle than layers. Within GM, myofiber number and CSA were 2.3- and 2.4-fold greater, respectively, in broilers than layers. In addition, the total number of muscle bundles and bundle CSA were 2.5- and 2.1-fold greater, respectively, in broilers than in the layers. The novel findings of the current study provide evidence that greater muscle mass of broilers occurs by both hyperplasia and hypertrophy of muscle bundles and myofibers

Analysis of seasonal variation of antibiotic prescribing for respiratory tract diagnoses in primary care practices

Abstract Objective: To determine antibiotic prescribing appropriateness for respiratory tract diagnoses (RTD) by season. Design: Retrospective cohort study. Setting: Primary care practices in a university health system. Patients: Patients who were seen at an office visit with diagnostic code for RTD. Methods: Office visits for the entire cohort were categorized based on ICD-10 codes by the likelihood that an antibiotic was indicated (tier 1: always indicated; tier 2: sometimes indicated; tier 3: rarely indicated). Medical records were reviewed for 1,200 randomly selected office visits to determine appropriateness. Based on this reference standard, metrics and prescriber characteristics associated with inappropriate antibiotic prescribing were determined. Characteristics of antibiotic prescribing were compared between winter and summer months. Results: A significantly greater proportion of RTD visits had an antibiotic prescribed in winter [20,558/51,090 (40.2%)] compared to summer months [11,728/38,537 (30.4%)][standardized difference (SD) = 0.21]. A significantly greater proportion of winter compared to summer visits was associated with tier 2 RTDs (29.4% vs 23.4%, SD = 0.14), but less tier 3 RTDs (68.4% vs 74.4%, SD = 0.13). A greater proportion of visits in winter compared to summer months had an antibiotic prescribed for tier 2 RTDs (80.2% vs 74.2%, SD = 0.14) and tier 3 RTDs (22.9% vs 16.2%, SD = 0.17). The proportion of inappropriate antibiotic prescribing was higher in winter compared to summer months (72.4% vs 62.0%, P < .01). Conclusions: Increases in antibiotic prescribing for RTD visits from summer to winter were likely driven by shifts in diagnoses as well as increases in prescribing for certain diagnoses. At least some of this increased prescribing was inappropriate

Resource utilization and costs during the initial years of lung cancer screening with computed tomography in Canada

Background It is estimated that millions of North Americans would qualify for lung cancer screening and that billions of dollars of national health expenditures would be required to support population-based computed tomography lung cancer screening programs. The decision to implement such programs should be informed by data on resource utilization and costs. Methods Resource utilization data were collected prospectively from 2059 participants in the Pan-Canadian Early Detection of Lung Cancer Study using low-dose computed tomography (LDCT). Participants who had 2% or greater lung cancer risk over 3 years using a risk prediction tool were recruited from seven major cities across Canada. A cost analysis was conducted from the Canadian public payer's perspective for resources that were used for the screening and treatment of lung cancer in the initial years of the study. Results The average per-person cost for screening individuals with LDCT was USD453 (95% confidence interval [CI], USD400–USD505) for the initial 18-months of screening following a baseline scan. The screening costs were highly dependent on the detected lung nodule size, presence of cancer, screening intervention, and the screening center. The mean per-person cost of treating lung cancer with curative surgery was USD33,344 (95% CI, USD31,553–USD34,935) over 2 years. This was lower than the cost of treating advanced-stage lung cancer with chemotherapy, radiotherapy, or supportive care alone, (USD47,792; 95% CI, USD43,254–USD52,200; p = 0.061). Conclusion In the Pan-Canadian study, the average cost to screen individuals with a high risk for developing lung cancer using LDCT and the average initial cost of curative intent treatment were lower than the average per-person cost of treating advanced stage lung cancer which infrequently results in a cure

Effects of full litter reuse with or without chemical amendment on measures of welfare and performance on three Australian broiler farms

There are pressures on some sectors of the Australian broiler industry to reuse poultry litter for multiple batches of chickens. We investigated the effects of reused litter on bird performance, welfare, litter pH and moisture, and air ammonia concentrations on three commercial farms (A, B, and C) across NSW, Australia. On each farm, the litter inside six sheds was assigned to one of three treatments: 1) a full cleanout replenished with new litter (NL); 2) litter reuse in the entire shed following heaping and turning (RL); and 3) RL plus the addition of a commercial acidifying litter amendment (RL+A). In the RL and RL+A sheds, chicks were placed directly on reused litter. Bird performance, welfare, and litter measurements were made on days 0, 7, 14, and 35. Feed conversion ratios (adjusted to 2.45kg) on a whole farm basis were 1.868, 1.839 and 1.920 for farms A, B, and C, respectively. Day 35 weights were highest on RL on all 3 farms but the effect of litter treatment on mortality varied between farms, with some indication that placing chicks on reused litter less than 3 days after re-spreading increased early mortality. On all three farms, welfare measures provided no evidence of sustained reduction in welfare status of birds on reused litter, nor any clear benefits or disadvantages of litter amendment. Litter moisture content and pH varied significantly with treatment and time on all farms. On the reused litter treatments, moisture content increased steadily on all farms between placement and day 35, with no effect of litter amendment. The litter amendment also failed to lower the pH of the reused litter at any time; however, it did appear to have a reducing effect on air ammonia concentrations relative to the RL treatment on farms B and C. In conclusion, bird performance and welfare can be maintained on reused litter if managed properly

Real-time surveillance and response system for Ebola and other emerging infections

ObjectiveWe will describe a real-time mobile surveillance and casemanagement system designed to organize data collected bymultiple officers about cases and their contacts. We will discuss thissurveillance system and its application for Ebola and other infectiousdiseases in the Democratic Republic of the Congo (DRC) and othersimilar settings. We will review the technology, results, challenges,lessons-learned, and applicability to other contexts.IntroductionImproving surveillance and response is a critical component ofthe Global Health Security Agenda. While it is impossible to predictwhere the next Ebola outbreak will occur, it is very likely that anotheroutbreak will occur in the DRC. Of the 20 known outbreaks, 7 haveoccurred in the DRC, one as recently as 2014. To rapidly detectand respond to an Ebola outbreak, we sought to develop a real-timesurveillance and response system for use in DRC and similar settings.RTI International developed Coconut Surveillance mobile software,which is currently used for real-time malaria surveillance andresponse in Zanzibar, Africa, where malaria elimination efforts areunderway. We took this system and adapted it for Ebola as a possibletool for surveillance and response to Ebola and other (re)emergingdiseases. Plans include pilot testing functionality at clinical sites inDRC, where surveillance infrastructure is limited at the local level.Coconut Surveillance is a mobile disease surveillance and rapidresponse system currently used for malaria elimination activities.It receives suspected positive case alerts from the field via mobilephones and uses mobile software to guide surveillance officersthrough a follow-up process. Coconut Surveillance runs on Androidmobile devices that are used to coordinate work in the field as well asprovide decision support during data collection and case management.In addition to standard case information, the GPS coordinates ofthe case’s household are captured as well as malaria status of allhousehold members. Data are collected and accessed off-line, and aresynchronized with a shared database when Internet connectivity isavailable. This tool has been used successfully in Zanzibar for morethan three years and has been recognized as one of the most advancedapplications of its kind.MethodsWe adapted the Coconut Surveillance system for Ebolasurveillance and response, and expanded the system for use with othercommunicable diseases. With a near real-time outbreak detectionsystem for Ebola, we may reduce the response time and contain anoutbreak faster. Using a cloud-based data repository, the modifiedCoconut System, known as Coconut Plus, also has the added value ofcase and case-contacts specific information sharing in real-time withthe national, provincial, and district level public health authorities,who would have convenient and secure access to case and contactinformation via the Internet. The software modifications to theCoconut System have been informed by testing and stakeholderfeedback.ResultsWe have developed Coconut Plus around the Coconut softwarearchitecture, which allows the team to quickly develop specificworkflows and applications, such as contact tracing, on top of a solidand well-supported base. Additionally, the adaptation was structuredto accommodate the build-out of multiple diseases, and is uniquelyhelpful for diseases that require tracking many contacts. We weregranted access in DRC to test interoperability with DHIS 2, the mostwidely used health information system software in Ebola effectedcountries. Coconut Plus is now using the DHIS 2 organizationalhierarchy definition, which means that organizational hierarchy(including information on administrative units and health carefacilities) can be exported directly from DHIS 2 to Coconut Plus.Stakeholder feedback on the usability and feasibility of the adaptedsystem has been enthusiastic, and stressed the need for additionalresources to make a pilot successful, including mobile phones andimproved mobility of surveillance staff in the field. The followingscreencast provides an overview of the application: https://www.youtube.com/watch?v=jjLT3pLLW-UConclusionsCoconut Surveillance Plus solves an absence of a real-time mobiledecision support disease surveillance and response system that can beused for Ebola and other infectious diseases in countries with limitedsurveillance infrastructure. More broadly, this system could also beused for many communicable diseases that require contact tracing andan urgent outbreak response in environments that require rapid scaleup of a distributed surveillance, rapid response, and case managementsystem