Effect of age, sex and fertility on the optimal structure of a static self-replacing ewe and wether flock

1975 ◽  
Vol 15 (76) ◽  
pp. 610 ◽  
Author(s):  
R Jardine ◽  
PD Mullaney ◽  
ED Turnbull ◽  
JK Egan
Keyword(s):  
Nutritional Stress ◽  
Optimal Structure ◽  
Biological Factors ◽  
Optimal Structures ◽  
Wide Range ◽  
Fixed Set ◽  
Effect Of Age

This study investigated the optimal structure of a closed ewe and wether flock producing wool and meat. A range of price-weighted (net of a fixed set of costs) combinations of these products was considered, and optimal structures determined for each. The aim of the study was to throw some light on the effects of the main biological factors-age, sex and fertility-on flock structure (given that there is no nutritional stress). The general conclusions were that the optimal structure shifts from disposing of wethers as lambs and ewes as 5.5-year olds to disposing of wethers as 3.5-year olds and ewes as 4.5-year olds, as fertility declines or meat declines in value relative to wool. However, the former structure tends to dominate and is optimal over a wide range of conditions.

scholarly journals Goal-driven active learning

2021 ◽  
Vol 35 (2) ◽  
Author(s):  
Nicolas Bougie ◽  
Ryutaro Ichise
Keyword(s):  
Decision Making ◽  
Reinforcement Learning ◽  
Learning Process ◽  
Real World ◽  
Imitation Learning ◽  
Learning Approaches ◽  
Wide Range ◽  
Fixed Set ◽  
Complex Decision Making ◽  
Complex Decision

AbstractDeep reinforcement learning methods have achieved significant successes in complex decision-making problems. In fact, they traditionally rely on well-designed extrinsic rewards, which limits their applicability to many real-world tasks where rewards are naturally sparse. While cloning behaviors provided by an expert is a promising approach to the exploration problem, learning from a fixed set of demonstrations may be impracticable due to lack of state coverage or distribution mismatch—when the learner’s goal deviates from the demonstrated behaviors. Besides, we are interested in learning how to reach a wide range of goals from the same set of demonstrations. In this work we propose a novel goal-conditioned method that leverages very small sets of goal-driven demonstrations to massively accelerate the learning process. Crucially, we introduce the concept of active goal-driven demonstrations to query the demonstrator only in hard-to-learn and uncertain regions of the state space. We further present a strategy for prioritizing sampling of goals where the disagreement between the expert and the policy is maximized. We evaluate our method on a variety of benchmark environments from the Mujoco domain. Experimental results show that our method outperforms prior imitation learning approaches in most of the tasks in terms of exploration efficiency and average scores.

Development of Commercial Quality Software for Mechanisms Design Education

1992 ◽  
Author(s):  
Steven J. Timmins
Keyword(s):  
Design Education ◽  
Educational Software ◽  
Free Form ◽  
Single Individual ◽  
University Environment ◽  
Persistent Problem ◽  
Institutions Of Higher Learning ◽  
Wide Range ◽  
Fixed Set ◽  
Develop Software

Abstract Development of high quality technical software in a university environment has been a persistent problem since the introduction of educational software to institutions of higher learning. Design software presents a number of special considerations. It differs significantly from other types of educational software in that it requires a free-form creative environment rather than a question-and-answer format or even a detailed analysis of a fixed set of specified problems. Ideally, the student should be able to explore a wide range of realistic problems and develop both optimal and non-optimal solutions using a variety of mechanisms. This paper outlines the differences between truly “commercial quality” software and that developed for use at the local campus and explores the difficulties involved in producing such a product. Users drastically underestimate the amount of manpower and funding required to develop software packages on a par with widely available applications such as AutoCAD, WordPerfect, or Lotus 1-2-3. Similarly, design education software developed at universities for national distribution represent thousands of man-hours of development and may be the work of a single individual or a team of programmers led by a faculty member.

Multivariate design and analysis of aircraft HEX under multiple working conditions within flight envelope

2021 ◽  
pp. 1-18
Author(s):  
Qihang Liu ◽  
G.Q. Xu ◽  
Jie Wen ◽  
Yanchen Fu ◽  
Laihe Zhuang ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Working Conditions ◽  
Design Method ◽  
Structural Parameters ◽  
Optimal Structure ◽  
Clear Correlation ◽  
Pressure Drops ◽  
Design Variables ◽  
Wide Range ◽  
Common Weight

Abstract This paper presents a multi-condition design method for the aircraft heat exchanger (HEX), marking with light weight, compactness and wide range of working conditions. The quasi-traversal genetic algorithm (QT-GA) method is introduced to obtain the optimal values of five structural parameters including the height, the tube diameter, the tube pitch, and the tube rows. The QT-GA method solves the deficiency of the conventional GA in the convergence, and gives a clear correlation between design variables and outputs. Pressure drops, heat transfer and the weight of the HEX are combined in a single objective function of GA in the HEX design, thus the optimal structure of the HEX suitable for all the working conditions can be directly obtained. After optimization, the weight of the HEX is reduced to 2.250 kg, more than 20% lower than a common weight of around 3 kg. Based on the optimal structure, the off-design performance of the HEX is further analyzed. Results show that the extreme working conditions for the heat transfer and the pressure drops are not consistent. It proves the advance of the multi-condition design method over traditional single-condition design method. In general, the proposed QT-GA design method is an efficient way to solve the multi-condition problems related to the aircraft HEX or other energy systems.

Abstract 6238: Clarifying the Opportunities to Improve Survival After MI in Diabetic Patients

Circulation ◽  
2008 ◽  
Vol 118 (suppl_18) ◽  
Author(s):  
Lance S Longmore ◽  
Kimberly J Reid ◽  
Mikhail Kosiborod ◽  
Frederick A Masoudi ◽  
Verna Welch ◽  
...  
Keyword(s):  
Cardiovascular Disease ◽  
Patient Characteristics ◽  
Psychosocial Health ◽  
Diabetic Patients ◽  
Biological Factors ◽  
Increased Risk ◽  
Wide Range ◽  
Patients With Diabetes ◽  
Multivariable Models ◽  
Adjusted Model

While diabetes is known to be associated with increased mortality after MI, whether these differences in outcome are due to patient characteristics, treatment, or other biological factors is unknown. We analyzed a contemporary cohort of MI survivors to comprehensively adjust for demographics, comorbidities, psychosocial, health status, clinical and treatment factors to determine if residual disparities in outcomes exist. We studied 2481 hospital survivors of MI in the prospective, 19-center PREMIER study (29% with diabetes). Multivariable models with sequential adjustment were employed to identify the extent to which variation in a wide range of patient characteristics (Figure ) accounted for differences in 3-year mortality in patients with and without diabetes. Unadjusted mortality was more than 2.5-fold greater for patients with diabetes (HR 2.55, 95% CI 2.08–3.14). Mortality was most attenuated by diabetes-related comorbidities (Figure ). The fully-adjusted model identified a significant, albeit attenuated, excess 3-year mortality among patients with diabetes (HR 1.57, 95% CI 1.22–1.99). Patients with diabetes experience a substantially increased risk for 3-year mortality after MI, even after accounting for a wide range of patient and treatment characteristics. This suggests that unmeasured, biologic variables associated with diabetes may mediate this difference. Further inquiry into the pathogenesis of diabetic cardiovascular disease is needed to identify new opportunities to improve the prognosis of patients with diabetes.

scholarly journals Titer regulation in arthropod-Wolbachia symbioses

2019 ◽  
Vol 366 (23) ◽  
Author(s):  
Sergio López-Madrigal ◽  
Elves H Duarte
Keyword(s):  
Wolbachia Infection ◽  
Intracellular Bacteria ◽  
Biological Factors ◽  
Wolbachia Pipientis ◽  
Host Fitness ◽  
Symbiotic Associations ◽  
Infection Dynamics ◽  
Wide Range ◽  
High Prevalence ◽  
Fine Regulation

ABSTRACT Symbiosis between intracellular bacteria (endosymbionts) and animals are widespread. The alphaproteobacterium Wolbachia pipientis is known to maintain a variety of symbiotic associations, ranging from mutualism to parasitism, with a wide range of invertebrates. Wolbachia infection might deeply affect host fitness (e.g. reproductive manipulation and antiviral protection), which is thought to explain its high prevalence in nature. Bacterial loads significantly influence both the infection dynamics and the extent of bacteria-induced host phenotypes. Hence, fine regulation of bacterial titers is considered as a milestone in host-endosymbiont interplay. Here, we review both environmental and biological factors modulating Wolbachia titers in arthropods.

Age as a Factor in the Classroom Verbal Participation of Occupational Therapy Students: Part 1, Literature Review

1992 ◽  
Vol 55 (4) ◽  
pp. 134-136
Author(s):  
Catherine F Paterson
Keyword(s):  
Occupational Therapy ◽  
Literature Review ◽  
Occupational Therapy Students ◽  
Mature Students ◽  
Wide Range ◽  
Verbal Participation ◽  
Effect Of Age

This literature review forms the first of two articles on a study to determine the effect of age on the verbal participation of occupational therapy students in the classroom. The literature was reviewed to establish the relevance of studying the implications of having students of a wide range of age and experience in the same classroom; to examine what already has been studied in relation to adult and mature students; to establish the importance of discussion to learning; and, finally, to identify the factors that affect students' participation.

scholarly journals Effect of Age in Second Language Acquisition: A Critical Review from the Perspective of Critical Period Hypothesis and Ultimate Attainment

2017 ◽  
Vol 7 (5) ◽  
pp. 1 ◽  
Author(s):  
Mohammad Mosiur Rahman ◽  
Ambigapathy Pandian ◽  
Abdul Karim ◽  
Faheem Hasan Shahed
Keyword(s):  
Second Language ◽  
Second Language Acquisition ◽  
Language Acquisition ◽  
Critical Period ◽  
Secondary Data ◽  
Future Research ◽  
Critical Period Hypothesis ◽  
Wide Range ◽  
Ultimate Attainment ◽  
Effect Of Age

This article addresses the effect of age in Second Language Acquisition (SLA), posing the relative question that whether the Critical Period hypothesis (CPH) exists in Second Language (SL), and if existing, how it is associated duly with SLA. The justification of comparing the achievement of L1 and L2 learners on the basis of Ultimate Attainment (UA) in the establishment of Critical Period Hypothesis, is also discussed. In the methodology, secondary data analysis was used to answer of research questions. To achieve a reliable result from the wide range of secondary data primarily from journal articles, a systemic search has been adopted. In conclusion, compare and contrast was made with earlier studies to show the findings of the study and to scope future research. 

A new approach to the measurement of the quantitative effects of inherent and environmental factors on the composition of the milk of individual cows and of herds, with particular reference to lactose content

1968 ◽  
Vol 35 (1) ◽  
pp. 91-105 ◽  
Author(s):  
J. P. Walsh ◽  
J. A. F. Rook ◽  
F. H. Dodd
Keyword(s):  
Quantitative Estimation ◽  
Relative Importance ◽  
New Approach ◽  
Mean Values ◽  
Stage Of Lactation ◽  
Bulk Milk ◽  
Wide Range ◽  
The Mean ◽  
The Difference ◽  
Effect Of Age

Summary(1) A tentative scheme is proposed for the quantitative estimation of the effects of various factors on one major milk constituent, lactose, from analyses of the milk of individual cows within herds. The potential lactose content in the milk of individual cows is predicted from the observed potassium-to-lactose ratio in the milk, and the difference between the predicted potential and the actual lactose content is partitioned into fractions that are attributed to effects due to age, inter-quarter difference and changes with stage of lactation. The scheme was applied to 2 commercial herds, one (herd A) producing milk of low and the other (herd B) milk of normal SNF content.(2) Lactation mean values for fat, SNF and lactose contents of the milk of individual cows showed a wide range of the same order in each of the 2 herds. Of the mean difference in SNF percentage of 0·30 between the herds, 0·14, or 47%, was due to a difference in lactose content.(3) The predicted potential milk lactose content of the cows in the 2 herds ranged from 5·04 to 5·66 (g/100 g milk water). Herd mean values were 5·394 for herd A and 5·244 for herd B.(4) Herd mean values for the effect on the lactose content (g/100 g milk water) of age, of changes with stage of lactation and of inter-quarter difference were −0·127, −0·080, and 0·073 respectively in herd A, and −0·197, −0·058 and −0·078, respectively, in herd B.(5) The relative importance of the various factors in accounting for differences between the herds in the lactose content of their bulk milk were: predicted potential lactose content 61%, effect of age 28%, effect of changes with stage of lactation 9% and effect of inter-quarter difference 2%.(6) The errors attached to the estimation of potential milk lactose content and the effects of age, of changes with stage of lactation and of inter-quarter difference are discussed.

scholarly journals Age-Dependent Decline in Salinity Tolerance in a Euryhaline Fish

2021 ◽  
Vol 2 ◽  
Author(s):  
Mayu Inokuchi ◽  
Yoko Yamaguchi ◽  
Benjamin P. Moorman ◽  
Andre P. Seale
Keyword(s):  
Environmental Control ◽  
Survival Rates ◽  
Age Related ◽  
Acclimation Period ◽  
Wide Range ◽  
Osmotic Homeostasis ◽  
Age Dependent ◽  
Euryhaline Teleost ◽  
Salinity Challenge ◽  
Effect Of Age

Euryhaline teleost fish are characterized by their ability to tolerate a wide range of environmental salinities by modifying the function of osmoregulatory cells and tissues. In this study, we experimentally addressed the age-related decline in the sensitivity of osmoregulatory transcripts associated with a transfer from fresh water (FW) to seawater (SW) in the euryhaline teleost, Mozambique tilapia, Oreochromis mossambicus. The survival rates of tilapia transferred from FW to SW were inversely related with age, indicating that older fish require a longer acclimation period during a salinity challenge. The relative expression of Na+/K+/2Cl− cotransporter 1a (nkcc1a), which plays an important role in hyposmoregulation, was significantly upregulated in younger fish after SW transfer, indicating a clear effect of age in the sensitivity of branchial ionocytes. Prolactin (Prl), a hyperosmoregulatory hormone in O. mossambicus, is released in direct response to a fall in extracellular osmolality. Prl cells of 4-month-old tilapia were sensitive to hyposmotic stimuli, while those of >24-month-old fish did not respond. Moreover, the responsiveness of branchial ionocytes to Prl was more robust in younger fish. Taken together, multiple aspects of osmotic homeostasis, from osmoreception to hormonal and environmental control of osmoregulation, declined in older fish. This decline appears to undermine the ability of older fish to survive transfer to hyperosmotic environments.

Survival and dormancy of purple nutsedge (Cyperus rotundus) tubers

Weed Science ◽  
1997 ◽  
Vol 45 (6) ◽  
pp. 784-790 ◽  
Author(s):  
Christophe Neeser ◽  
Renan Aguero ◽  
Clarence J. Swanton
Keyword(s):  
Population Dynamics ◽  
Field Studies ◽  
Cyperus Rotundus ◽  
Burial Depth ◽  
Tuber Dormancy ◽  
Purple Nutsedge ◽  
Wide Range ◽  
Noxious Weed ◽  
First Time ◽  
Effect Of Age

Survival and dormancy of purple nutsedge tubers has not been studied quantitatively. Yet this is fundamental to our understanding of the population dynamics of this highly noxious weed. Field studies were conducted to determine the effect of age on tuber survival and dormancy. A modified exponential decay function accurately described the age-dependent decline in tuber survival. This model is biologically meaningful, has good statistical properties, and can describe a wide range of responses. Tuber population half-life was 16 mo, and the predicted longevity (99% mortality) was 42 mo. Burial depth at 8 and 23 cm had no significant effect on survival or dormancy. Tuber dormancy increased with age. After 18 mo, the proportion of dormant tubers in the surviving population was two-and-one-half times higher than in the 3-mo-old population. We report for the first time that tubers were able to enter a state of secondary dormancy after sprouting. The finding that tubers persist after sprouting has important implications for population dynamics of this species. This is also the first report of tuber predation by the larvae of a billbug.

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