The lactation cycle of Elephantulus myurus jamesoni (Chubb)

1954 ◽  
Vol 238 (653) ◽  
pp. 62-98 ◽  
Keyword(s):  
Breeding Season ◽  
Mammary Glands ◽  
Subsequent Pregnancy ◽  
Individual Animal ◽  
Final State ◽  
Amniotic Cavity ◽  
Regular Cycle ◽  
The Individual ◽  
Lactation Cycle ◽  
Second Period

The development of the mammary glands follows the same course during all first pregnancies, regardless of the time of the breeding season. When a second or third pregnancy occurs at the beginning of the breeding season, the development of the glands during the pregnancy resembles the development during the first pregnancy once the embryos have reached the primary amniotic cavity stage. In all other pregnancies the development is complicated by a concurrent lactation and later involution. However, the structure of the glands during lactation is essentially the same, regardless of which pregnancy it follows, and of whether the lactation overlaps with a subsequent pregnancy, or occurs during anoestrus. Therefore it seems that the presence of developing embryos does not influence the course of lactation in any way. Owing to this similarity, the structure of the glands is the same in both the second and third pregnancies until the developing embryos are approximately 5 mm long, if the pregnancy occurs during the middle or at the end of the breeding season. It appears that the young are weaned when the developing embryos reach this size, i.e. 5 mm long. However, the changes in the glands during involution are affected not only by the time of the breeding season, but also by the pregnancy of the individual animal. When involution occurs during anoestrus it proceeds until a final state, only slightly more developed than the virgin condition, is reached. When involution occurs concurrent with the next pregnancy it differs according to the pregnancy of the individual animal. After a third pregnancy, which commenced either at the beginning or during the middle of the breeding season, the animal usually dies of old age before involution is established, but after a first or second pregnancy commencing at these times, involution takes place during the subsequent pregnancy. In these animals the extent to which the involution proceeds is governed by the size attained by the developing embryos at that particular time. When the involution occurs during a second pregnancy, i.e. after the first period of lactation, the most involuted condition is found when the embryos are 32-6 mm long. When it occurs during a third pregnancy, i.e. after the second period of lactation, involution is completed earlier, when the embryos are only 13-7 mm long, and this involution is more pronounced than that occurring during the second pregnancy. It is difficult to explain why this first period of involution should be more gradual, and take so much longer than the second. Moreover, in the latter there is a definite point whereafter involution is striking and rapid; this does not occur during the first period of involution. The only feasible explanation I can offer is that possibly, during the first period of pregnancy, lactation, and then involution, the regular cycle has not yet been established in the mammary glands. After this stage they may be fully mature, and the cycle stabilized.

scholarly journals Does SUSY have friends? A new approach for LHC event analysis

2021 ◽  
Vol 2021 (2) ◽  
Author(s):  
Anna Mullin ◽  
Stuart Nicholls ◽  
Holly Pacey ◽  
Michael Parker ◽  
Martin White ◽  
...  
Keyword(s):  
Hadron Collider ◽  
Local Network ◽  
Proton Collision ◽  
Event Analysis ◽  
Final State ◽  
Proton Proton ◽  
Kinematic Space ◽  
Boosted Decision Tree ◽  
The Individual ◽  
Particle Search

Abstract We present a novel technique for the analysis of proton-proton collision events from the ATLAS and CMS experiments at the Large Hadron Collider. For a given final state and choice of kinematic variables, we build a graph network in which the individual events appear as weighted nodes, with edges between events defined by their distance in kinematic space. We then show that it is possible to calculate local metrics of the network that serve as event-by-event variables for separating signal and background processes, and we evaluate these for a number of different networks that are derived from different distance metrics. Using a supersymmetric electroweakino and stop production as examples, we construct prototype analyses that take account of the fact that the number of simulated Monte Carlo events used in an LHC analysis may differ from the number of events expected in the LHC dataset, allowing an accurate background estimate for a particle search at the LHC to be derived. For the electroweakino example, we show that the use of network variables outperforms both cut-and-count analyses that use the original variables and a boosted decision tree trained on the original variables. The stop example, deliberately chosen to be difficult to exclude due its kinematic similarity with the top background, demonstrates that network variables are not automatically sensitive to BSM physics. Nevertheless, we identify local network metrics that show promise if their robustness under certain assumptions of node-weighted networks can be confirmed.

Between Guess Work and Certainty in Psychiatry

PEDIATRICS ◽  
1958 ◽  
Vol 21 (6) ◽  
pp. 949-949
Keyword(s):  
Subject Matter ◽  
Scientific Method ◽  
Individual Animal ◽  
Fundamental Distinction ◽  
The Subject ◽  
The Common ◽  
The Individual ◽  
Rational Inquiry

"The safeguards contained in the scientific method are repugnant to some who devote themselves to psychotherapy, and their argument against it always harks back to the uniqueness of the individual." The author points out that this is an obscurantist argument and it does not follow that because an individual is a unique reality, he cannot be compared with anyone else. On this basis there would be no science of zoology as every individual animal is also a unique reality, but this has not been an obstacle to comparison and collective study in this science. The argument is reminiscent of claims prevalent during the controversies about evolution when the opponents asserted that man was an improper subject for comparitive study because of his fundamental distinction from all other creatures. Only insofar as the common denominators between individuals can be ascertained may the subject matter of psychiatry become the object of scientific and rational inquiry and without this it could not be taught. We would be in the position of having to accept the pronouncements of supposedly singularly gifted individuals on faith, and continuity in the field would presumably depend entirely upon apprenticeship.

scholarly journals Equifinality and its violations in a redundant system: multifinger accurate force production

2013 ◽  
Vol 110 (8) ◽  
pp. 1965-1973 ◽  
Author(s):  
Luke Wilhelm ◽  
Vladimir M. Zatsiorsky ◽  
Mark L. Latash
Keyword(s):  
Force Production ◽  
Uncontrolled Manifold ◽  
Total Force ◽  
Redundant System ◽  
Uncontrolled Manifold Hypothesis ◽  
Final State ◽  
Performance Variables ◽  
Force Mode ◽  
Finger Forces ◽  
The Individual

We explored a hypothesis that transient perturbations applied to a redundant system result in equifinality in the space of task-related performance variables but not in the space of elemental variables. The subjects pressed with four fingers and produced an accurate constant total force level. The “inverse piano” device was used to lift and lower one of the fingers smoothly. The subjects were instructed “not to intervene voluntarily” with possible force changes. Analysis was performed in spaces of finger forces and finger modes (hypothetical neural commands to fingers) as elemental variables. Lifting a finger led to an increase in its force and a decrease in the forces of the other three fingers; the total force increased. Lowering the finger back led to a drop in the force of the perturbed finger. At the final state, the sum of the variances of finger forces/modes computed across repetitive trials was significantly higher than the variance of the total force/mode. Most variance of the individual finger force/mode changes between the preperturbation and postperturbation states was compatible with constant total force. We conclude that a transient perturbation applied to a redundant system leads to relatively small variance in the task-related performance variable (equifinality), whereas in the space of elemental variables much more variance occurs that does not lead to total force changes. We interpret the results within a general theoretical scheme that incorporates the ideas of hierarchically organized control, control with referent configurations, synergic control, and the uncontrolled manifold hypothesis.

scholarly journals Longitudinal Study of Shiga Toxin-Producing Escherichia coli Shedding in Sheep Feces: Persistence of Specific Clones in Sheep Flocks

2009 ◽  
Vol 75 (6) ◽  
pp. 1769-1773 ◽  
Author(s):  
Sergio Sánchez ◽  
Remigio Martínez ◽  
Alfredo García ◽  
Jorge Blanco ◽  
Jesús E. Blanco ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Longitudinal Study ◽  
Shiga Toxin ◽  
Gel Electrophoresis ◽  
Pulsed Field Gel Electrophoresis ◽  
Individual Animal ◽  
Pulsed Field ◽  
The Individual ◽  
Sheep Feces

ABSTRACT To provide information on the persistence and maintenance of colonization with Shiga toxin-producing Escherichia coli (STEC) in sheep, pulsed-field gel electrophoresis analysis of STEC isolates (n = 145) belonging to serogroups O5, O91, and O146 from 39 healthy animals was performed in a 12-month longitudinal study carried out with four sheep flocks. At the flock level as well as the individual-animal level, the same clones were obtained on sampling occasions separated by as much as 11 months.

The apparent digestibility of maize grain when given in various physical forms to adult sheep and cattle

1973 ◽  
Vol 80 (2) ◽  
pp. 259-267 ◽  
Author(s):  
G. F. Wilson ◽  
N. N. Adeeb ◽  
R. C. Campling
Keyword(s):  
Particle Size ◽  
Apparent Digestibility ◽  
Individual Animal ◽  
High Moisture ◽  
Lactating Cows ◽  
Effect Of Particle Size ◽  
Maize Grain ◽  
The Individual ◽  
Maize Kernels ◽  
Male Sheep

SummaryA series of digestibility trials was conducted with non-lactating cows and adult castrated male sheep given diets of hay and dried or high-moisture maize grain in various physical forms. Sheep were able to digest all forms of maize well and to a greater extent than cows. In cows considerable variation in digestibility of maize was associated with the particle size of the maize and the individual animal. Maximum digestibility of dried maize in cows ensued when the modulus of fineness lay within the range 4·7–3·0 and with high moisture maize from 5·4 to 5·1. A study was made of the effect of particle size on the rate of digestion of maize suspended in nylon bags in the rumen. Evidence was presented showing the importance of rumination in ensuring the digestion of intact kernels. Possible causes of differences between cows in their ability to digest intact maize kernels are discussed.

Reproductive biology of the parsley frog, Pelodytes punctatus, at the northernmost part of its range

1993 ◽  
Vol 14 (2) ◽  
pp. 131-147 ◽  
Author(s):  
M. Ohm ◽  
A.G. Toxopeus ◽  
J.W. Arntzen
Keyword(s):  
Reproductive Biology ◽  
Breeding Season ◽  
Adult Population ◽  
First Year ◽  
Adult Size ◽  
Dune System ◽  
Population Size Estimates ◽  
Coastal Dune System ◽  
Source Sink ◽  
Second Period

AbstractThe reproductive biology and population dynamics of Pelodytes punctatus were studied at the breeding season over a three year period in a coastal dune system located at the extreme northwestern border of the species' range. Adult population size estimates ranged from about 100 in the first year to 60 in the third year. Males were remarkably sedentary near the pond under artificially provided shelters. Many were observed during the most of the breeding season which lasted from mid-March or the end of March to the end of April or mid-May. Most spawning took place in the second half of March or early April. In two years out of three a second period of spawning involving fewer animals was observed in the first half of May. Both periods of spawning coincided with, or shortly followed, periods of rising median air temperature. Egg-clutches were deposited in the deepest parts of pond, mainly on submerged vegetation not reaching the surface. An average sized clutch contained approximately 360 eggs. Development of the embryos until hatching took from 4 to 14 days, depending on the ambient temperature. Larval development and growth were fast. Recently metamorphosed froglets at a size of around 18 mm were found from the end of May onwards. Juveniles may reach adult size in the autumn of the year that they were born. Adult frogs did not show a strong fidelity to the breeding pond between years. In the study area the population structure of Pelodytes punctatus seems to be best described by a source - sink model in which flourishing populations in the dunes give rise to short lived satellite populations outside the dunes.

DYNAMICS WITH CO-EVOLUTION OF INDIVIDUAL INCLINATION AND OPINION

2011 ◽  
Vol 22 (01) ◽  
pp. 51-62 ◽  
Author(s):  
FEI XIONG ◽  
YUN LIU ◽  
ZHENJIANG ZHANG
Keyword(s):  
Opinion Dynamics ◽  
Spin Systems ◽  
Voter Model ◽  
Formation Model ◽  
Opinion Formation ◽  
Final State ◽  
Memory Length ◽  
Slowing Down ◽  
The Past ◽  
The Individual

Based on the voter model, we present a new opinion formation model which takes into account the evolution of both opinions and individual inclinations. A memory-based inclination is developed gradually during the process of social interaction; however, if the individual inclination gets strong enough, it will react to opinion dynamics. We assume that an individual inclination increases with the number of times the individual has held its most frequent opinion in the past interactions. As a result of inclination choices the transition rate following neighbors decreases, thus slowing down the microscopic dynamics. Analytical and simulation results indicate the system under the action of opinion inclinations evolves to a more polarized state for average opinion. The appearance of extremists holding the minority opinion is observed in the final state, where one opinion predominates. It is also found that the stable opinion and relaxation time depend on network topology and memory length. Moreover, this model is not only valid to the voter model, but can also be applied to other spin systems.

The effect of melatonin implants on breeding activity and litter size in commercial sheep flocks in the UK

1990 ◽  
Vol 50 (1) ◽  
pp. 111-121 ◽  
Author(s):  
W. Haresign ◽  
A. R. Peters ◽  
L. D. Staples
Keyword(s):  
Breeding Season ◽  
Litter Size ◽  
Statistical Significance ◽  
Mating Period ◽  
The United Kingdom ◽  
Commercial Farming ◽  
Natural Breeding ◽  
The Individual ◽  
The Uk ◽  
Subcutaneous Implant

ABSTRACTTwo trials were undertaken to investigate the effects of treating seasonally anoestrous ewes with melatonin implants on date of first oestrus and other aspects of reproductive performance.Trial 1 involved a total of 368 Mule ewes and 79 Scottish Blackface ewes on five farms, approximately half of which were treated with a single subcutaneous implant of melatonin (Regulin®), containing 18 mg melatonin, between 23 July and 6 August 1986 and the remainder acted as untreated controls. Treatment had no significant effect on the date of first oestrus or conception rate in Mule ewes, although it increased the number of Scottish Blackface ewes mating (92% v. 73%) and the number of mated ewes conceiving (69% v. 54%) in a 5-week mating period, resulting in significantly more treated ewes lambing (63% v. 37%; P < 0·01). Litter size was higher in 4/5 flocks, although this only reached statistical significance in one Mule flock and the Scottish Blackface flock.A total of 2116 ewes from 17 commercial flocks were used in trial 2, approximately half of which were Suffolk/Suffolk-cross ewes and the remainder Mule/Mule-cross ewes. Implantation with melatonin occurred between 22 June and 24 July 1987. Flocks with over 100 ewes were divided into three equal-sized groups and treated with either 18 mg melatonin (one implant of Regulin, 36 mg melatonin (two implants of Regulin given at the same time) or acted as untreated controls. Flocks with less than 100 ewes contained only the 18 mg melatonin and untreated control groups. Treatment with melatonin significantly advanced the date of first oestrus in most flocks of both breeds (P < 0·05) but the magnitude of this effect was variable. Significant (P < 0·05 at least) increases in ‘potential’ (from scanning) mean litter size (+0·13 to +0·18) and actual mean litter size (+0·11 to +0·14) resulting from treatment with melatonin were apparent in ewes of both breeds when the data were pooled across all flocks, but only in 4/17 of the individual flocks.These results indicate that treatment with melatonin implants may be a simple and effective way of advancing the breeding season and enhancing litter size of early lambing flocks under commercial farming conditions in the United Kingdom, but treatment must be given >60 days before the start of the natural breeding season for benefits in date of first oestrus to be manifest.

CHANGES IN AGGRESSIVE AND SEXUAL RESPONSIVENESS OF MALE GOLDEN HAMSTERS AFTER NEONATAL ANDROGEN ADMINISTRATION

1977 ◽  
Vol 73 (2) ◽  
pp. 331-337 ◽  
Author(s):  
A. P. PAYNE
Keyword(s):  
Sexual Behaviour ◽  
Testosterone Propionate ◽  
Individual Animal ◽  
Ovarian Steroids ◽  
Golden Hamsters ◽  
Oestradiol Benzoate ◽  
The Individual ◽  
Male Golden Hamsters ◽  
Sexual Responsiveness

SUMMARY On day 1 after birth, male golden hamsters received either 300 μg of an androgen (testosterone propionate, testosterone, dihydrotestosterone or androstenedione) in 0·03 ml arachis oil, or oil alone. As intact adults, their aggressiveness towards unreceptive females was measured. After this, all animals were castrated. At least 3 weeks after the operation all animals received oestradiol benzoate (10 μg + progesterone (500 μg), after which their capacity to show patterns of female sexual behaviour towards a stud male was tested. Control hamsters which had received oil as neonates showed less aggression than the females with which they interacted; these controls also readily assumed lordosis after castration and priming with ovarian steroids. Conversely, animals which had received testosterone propionate or androstenedione neonatally were as aggressive as the female hamsters, and showed a markedly decreased ability to display lordotic behaviour after castration. The behaviour of male hamsters which received testosterone or dihydrotestosterone was unaffected. Thus, at the level of treatment used, increased aggressiveness appeared to co-vary with a decreased capacity to show female sexual behaviour patterns. However, within each treatment there was little evidence of such a relationship at the level of the individual animal.

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