Self-oscillation in a retroacting thermal conductor

1936 ◽  
Vol 32 (4) ◽  
pp. 663-675 ◽  
Author(s):  
L. B. Turner
Keyword(s):  
Sensitive Element ◽  
The Body ◽  
Critical Values ◽  
Heating Element ◽  
Temperature Sensitive ◽  
Automatic Temperature ◽  
Common Experience ◽  
Heating Current

In automatic temperature-controlling apparatus a temperature-sensitive element, commonly called a thermostat, serves to increase or decrease a supply of heat to the body or oven whose temperature is to be prevented from changing. The thermostat and heating elements are commonly both electrical, the thermostat comprising a “master coil” whose resistance changes with temperature, the heating element consisting of a “slave coil” carrying the heating current. The temperature of the master coil is made to control the current in the slave coil, usually by the interposition of some form of relay with the appropriate translating and amplifying apparatus. Since every form of relay exhibits “backlash”—the critical values of the operative signal at make and at break are not exactly equal—such a system necessarily oscillates or “hunts” through a range at least as great as the backlash of the relay; and since further there is thermal separation between the master coil and the slave coil, the hunting has a range exceeding the backlash of the relay. It is a common experience with such thermostatic apparatus that, owing to this action, continued improvement towards constancy of temperature is not attainable by increasing the delicacy with which the temperature of the master coil controls the current in the slave coil.

scholarly journals A genetic screen for temperature-sensitive morphogenesis-defectiveCaenorhabditis elegansmutants

2021 ◽  
Vol 11 (4) ◽  
Author(s):  
Molly C Jud ◽  
Josh Lowry ◽  
Thalia Padilla ◽  
Erin Clifford ◽  
Yuqi Yang ◽  
...  
Keyword(s):  
Cell Shape ◽  
The Body ◽  
Temperature Sensitive ◽  
Restrictive Temperature ◽  
Fundamental Biological Process ◽  
Embryonic Morphogenesis ◽  
Cell Shape Changes ◽  
Development Temperature ◽  
Multicellular Organisms ◽  
Shape Changes

AbstractMorphogenesis involves coordinated cell migrations and cell shape changes that generate tissues and organs, and organize the body plan. Cell adhesion and the cytoskeleton are important for executing morphogenesis, but their regulation remains poorly understood. As genes required for embryonic morphogenesis may have earlier roles in development, temperature-sensitive embryonic-lethal mutations are useful tools for investigating this process. From a collection of ∼200 such Caenorhabditis elegans mutants, we have identified 17 that have highly penetrant embryonic morphogenesis defects after upshifts from the permissive to the restrictive temperature, just prior to the cell shape changes that mediate elongation of the ovoid embryo into a vermiform larva. Using whole genome sequencing, we identified the causal mutations in seven affected genes. These include three genes that have roles in producing the extracellular matrix, which is known to affect the morphogenesis of epithelial tissues in multicellular organisms: the rib-1 and rib-2 genes encode glycosyltransferases, and the emb-9 gene encodes a collagen subunit. We also used live imaging to characterize epidermal cell shape dynamics in one mutant, or1219ts, and observed cell elongation defects during dorsal intercalation and ventral enclosure that may be responsible for the body elongation defects. These results indicate that our screen has identified factors that influence morphogenesis and provides a platform for advancing our understanding of this fundamental biological process.

What's hot and what's not: defining torpor in free-ranging birds and mammals

2001 ◽  
Vol 79 (10) ◽  
pp. 1885-1890 ◽  
Author(s):  
Robert MR Barclay ◽  
Cori L Lausen ◽  
Lydia Hollis
Keyword(s):  
Body Temperature ◽  
The Body ◽  
Temperature Sensitive ◽  
The Past ◽  
Data Loggers ◽  
Temperature Thresholds ◽  
Radio Transmitters ◽  
Species Specific ◽  
Free Ranging ◽  
Lowered Body

With the development of small implantable data loggers and externally attached temperature-sensitive radio transmitters, increasing attention is being paid to determining the thermoregulatory strategies of free-ranging birds and mammals. One of the constraints of such studies is that without a direct measure of metabolic rate, it is difficult to determine the significance of lowered body temperatures. We surveyed the literature and found that many different definitions have been used to discriminate torpor from normothermy. Many studies use arbitrary temperature thresholds without regard for the normothermic body temperature of the individuals or species involved. This variation makes comparison among studies difficult and means that ecologically and energetically significant small reductions in body temperature may be overlooked. We suggest that normothermic body temperature for each individual animal should be determined and that torpor be defined as occurring when the body temperature drops below that level. When individuals' active temperatures are not available, a species-specific value should be used. Of greater value, however, are the depth and duration of torpor bouts. We suggest several advantages of this definition over those used in the past.

SONOGRAPHIC MEASUREMENTS OF SCROTAL WALL THICKNESS

2021 ◽  
pp. 31-32
Author(s):  
Sahil Gandhi ◽  
Asit Natekar
Keyword(s):  
Wall Thickness ◽  
Tertiary Care ◽  
The Body ◽  
Wall Thickening ◽  
Temperature Sensitive ◽  
Main Function ◽  
Care Hospital ◽  
Sperm Production ◽  
Time Duration ◽  
Anterior Posterior

Main function of scrotum is to hold testes at optimal temperature for spermatogenesis. Sperm production in the testes is a temperature sensitive process. It requires an environment that is 2 to 6°C cooler than the body core. The temperature of the testes is regulated by the scrotal wall. Tunica dartos muscle changes the surface area of the scrotal skin by contracting or relaxing depending on the ambient temperature. This study postulates that if the thickness or the tone of this muscle is more thereby contributing to scrotal wall thickening, it will hamper the thermoregulation and spermatogenesis leading to poor sperm production. This could be an besides varicocoele another cause of male infertility which has been an established cause. This study will help to suspect the patients of infertility caused by thick scrotal wall. This study is aimed to study scrotal wall thickness and with the help of Ultrasonography. to establish norms The study was conducted at department of Radio-diagnosis at the tertiary care hospital, Sangli. The study started after approval of institutional ethical committee. This is a cross sectional observational study for the duration of 4 months. Total number of 50 cases was achieved in this time duration which satised the inclusion criteria. Statistical method used was Student's T test. Scrotal ultrasonography was performed using linear and curvilinear probe with sta (5-12 MHz) (2-5 MHz) on Philips Afniti50, after ndoff pad allowing some time for the dartos muscle to relax and scrotal wall thickness is measured on either side on three surfaces (anterior, posterior and lateral) and means were obtained. This study found that there was no difference between anterior, posterior, lateral wall thicknesses on ipsilateral side or contralateral side. There is no need to take three different wall thicknesses and convenience and suitability of any scrotal wall thickness would be equally effective.

Restoration of thermoregulation after exercise

2017 ◽  
Vol 122 (4) ◽  
pp. 933-944 ◽  
Author(s):  
Glen P. Kenny ◽  
Ryan McGinn
Keyword(s):  
Heat Loss ◽  
Core Temperature ◽  
Current Knowledge ◽  
Thermal Control ◽  
The Body ◽  
Body Core Temperature ◽  
Whole Body ◽  
Temperature Sensitive ◽  
Internal Core ◽  
Body Core

Performing exercise, especially in hot conditions, can heat the body, causing significant increases in internal body temperature. To offset this increase, powerful and highly developed autonomic thermoregulatory responses (i.e., skin blood flow and sweating) are activated to enhance whole body heat loss; a response mediated by temperature-sensitive receptors in both the skin and the internal core regions of the body. Independent of thermal control of heat loss, nonthermal factors can have profound consequences on the body’s ability to dissipate heat during exercise. These include the activation of the body’s sensory receptors (i.e., baroreceptors, metaboreceptors, mechanoreceptors, etc.) as well as phenotypic factors such as age, sex, acclimation, fitness, and chronic diseases (e.g., diabetes). The influence of these factors extends into recovery such that marked impairments in thermoregulatory function occur, leading to prolonged and sustained elevations in body core temperature. Irrespective of the level of hyperthermia, there is a time-dependent suppression of the body’s physiological ability to dissipate heat. This delay in the restoration of postexercise thermoregulation has been associated with disturbances in cardiovascular function which manifest most commonly as postexercise hypotension. This review examines the current knowledge regarding the restoration of thermoregulation postexercise. In addition, the factors that are thought to accelerate or delay the return of body core temperature to resting levels are highlighted with a particular emphasis on strategies to manage heat stress in athletic and/or occupational settings.

THERMOSENSITIVE NANOPARTICLES CONJUGATING WITH CD34 ANTIBODY AND ITS SOLUTION PEROPERTIES

2006 ◽  
Vol 18 (05) ◽  
pp. 222-228 ◽  
Author(s):  
CHUN-TE TAO ◽  
TAI-HORNG YOUNG
Keyword(s):  
Controlled Release ◽  
Cloud Point ◽  
Lower Critical Solution Temperature ◽  
Homogeneous Solution ◽  
The Body ◽  
Solution Temperature ◽  
Temperature Sensitive ◽  
Critical Solution Temperature ◽  
Human Cd34 ◽  
Collapse Temperature

Poly N-isopropylacrylamide (PNIPAAm) is a well-known temperature-sensitive polymer. When the temperature is higher than the lower critical solution temperature (LCST), PNIPAAm aquous solution is cloudy (phase separation occurred). In contrast, when the temperature is lower than the LCST, PNIPAAm is soluble in water (a homogeneous solution). The lower critical solution temperature (LCST) in aqueous solution of PNIPAAm was about 32~33°C. We prepared nano-scaled PNIPAAm particles containing carboxylic group on their surfaces by introducing acrylic acid monomer. The carboxylic groups were applied to conjugate with the amino group of the CD34 antibody. This immuno-conjugate can be applied on targeting the human CD34 positive cells, peripheral blood progenitor cells included, for cell purification and drug controlled release. In order to the active responding of controlled release of the conjugate in the body influenced by temperature, we hope to estimate the shifting of the gel-collapse temperature or cloud point of the immuno-conjugates by dynamic light scattering (DLS) and UV absorption. The results show that the gel-collapse temperature of the nano-particle was not significantly affected by the content of AA between 1.5~5 mol%. However, cloud point of the solution was elevated by the conjugation of CD34 antibody to 37°C. When CD34-conjugated particle was subsequently incorporated with recombinant FLT3-ligand, which is a smaller molecule compare to CD34 antibody, cloud point of the solution was not affected.

Temperature Regulated Sleeve for Leg Prosthesis

2019 ◽  
Author(s):  
Rachel Grubbs ◽  
Matthew Yough ◽  
Olivia Rose ◽  
Anthony Lee ◽  
Teresa Sicree ◽  
...  
Keyword(s):  
Heat Transfer ◽  
The Body ◽  
Heating Element ◽  
Heat Transfer Analysis ◽  
Research And Design ◽  
Leg Prosthesis

Abstract This paper presents the findings of the research and design of a heat generating thermal prosthetic sleeve. The goal of the project was to get the sleeve to be designed in a way that keeps a comfortable temperature of the amputation site. Heat transfer analysis as well as comfort tests were used to select the optimal materials for the body of the sleeve. A series of electrical tests using multimeters were used to determine which heating element should be used, as well as in which orientation they should be connected. A microcontroller system had also to be selected to give the sleeve some adjustability.

Fracture Analysis of an Oblique Crack Propagation in a Pre-Stressed Glass-Epoxy Composite

2008 ◽  
Vol 385-387 ◽  
pp. 733-736
Author(s):  
Eduard Marius Craciun ◽  
Adrian Carabineanu ◽  
Niculae Peride
Keyword(s):  
Crack Propagation ◽  
Applied Stress ◽  
Fracture Criterion ◽  
Epoxy Composite ◽  
Fracture Analysis ◽  
The Body ◽  
Critical Values ◽  
Elastic Composite ◽  
Oblique Crack ◽  
Crack Faces

We consider a pre-stressed material containing an oblique crack of a length 2a situated in x1x3 plane. We supposed that the material is unbounded and the crack faces are acted by constant normal incremental stresses p. The initial applied stress ◦ is in direction of the crack. Our first aim is to determine the elastic state produced in the body using Guz’s representation theorem. Our second aim is to determine the critical values of the incremental stresses and the direction of crack propagation. To do this, we use Sih’s generalised fracture criterion for an orthotropic elastic composite. In the last part we find the critical values of the initial applied stress ◦ for which the phenomenon of resonance can appear in a pre-stressed Glass-Epoxy composite.

scholarly journals Temperature-Sensitive Salmonella enterica Serovar Enteritidis PT13a Expressing Essential Proteins of Psychrophilic Bacteria

2015 ◽  
Vol 81 (19) ◽  
pp. 6757-6766 ◽  
Author(s):  
Barry N. Duplantis ◽  
Stephanie M. Puckett ◽  
Everett L. Rosey ◽  
Keith A. Ameiss ◽  
Angela D. Hartman ◽  
...  
Keyword(s):  
Salmonella Enterica ◽  
Type Strain ◽  
Wild Type Strain ◽  
Phage Type ◽  
The Body ◽  
Temperature Sensitive ◽  
Restrictive Temperature ◽  
Wild Type ◽  
Psychrophilic Bacteria ◽  
Content Type

ABSTRACTSynthetic genes based on deduced amino acid sequences of the NAD-dependent DNA ligase (ligA) and CTP synthetase (pyrG) of psychrophilic bacteria were substituted for their native homologues in the genome ofSalmonella entericaserovar Enteritidis phage type 13a (PT13a). The resulting strains were rendered temperature sensitive (TS) and did not revert to temperature resistance at a detectable level. At permissive temperatures, TS strains grew like the parental strain in broth medium and in macrophage-like cells, but their growth was slowed or stopped when they were shifted to a restrictive temperature. When injected into BALB/c mice at the base of the tail, representing a cool site of the body, the strains with restrictive temperatures of 37, 38.5, and 39°C persisted for less than 1 day, 4 to 7 days, and 20 to 28 days, respectively. The wild-type strain persisted at the site of inoculation for at least 28 days. The wild-type strain, but not the TS strains, was also found in spleen-plus-liver homogenates within 1 day of inoculation of the tail and was detectable in these organs for at least 28 days. Intramuscular vaccination of White Leghorn chickens with the PT13a strain carrying the psychrophilicpyrGgene provided some protection against colonization of the reproductive tract and induced an anti-S. entericaantibody response.

scholarly journals Transient skin and fur color change after trichotomy of the sacrococcygeal region for epidural anesthesia in a domestic cat (Felis catus)

2021 ◽  
Vol 58 ◽  
pp. e180388
Author(s):  
Amândio José Soares Dourado ◽  
Ignacio Sández Cordero ◽  
Anabela Filipa Rodrigues Gomes ◽  
Luís Pedro Rodrigues de Lima Lobo ◽  
Maria Isabel Ribeiro Dias
Keyword(s):  
Epidural Anesthesia ◽  
Skin Color ◽  
Hair Growth ◽  
Color Change ◽  
The Body ◽  
Pigment Production ◽  
Domestic Cat ◽  
Hair Color ◽  
Temperature Sensitive ◽  
Sacrococcygeal Region

A clinical case in which skin and hair color change occurred after sacrococcygeal epidural anesthesia in a nine-month-old Siamese cross queen undergoing ovariohysterectomy (OHE) is described. Six weeks after surgery, during a re-check, it was noted that in the sacrococcygeal region the color of the skin and new hair growth was dark with a color comparable to the color present on the body extremities (muzzle, pinnae, legs, and tail). The skin and new hair growth of the shaved abdomen presented a standard color. The key enzyme of the melanogenic pathway in mammals is tyrosinase (TYR), and the Siamese temperature-sensitive phenotype is the result of genetic mutations that makes TYR function thermolabile. The activity of TYR in these cats is limited to the extremities where the temperature is lower while pigment production is impaired in the other body areas. The trichotomy of the sacrococcygeal region performed during wintertime in an outdoor cat was probably the trigger for increased activity of TYR in this area promoting pigment production. The absence of the same alterations in the abdominal area may be justified by less exposure of that region to the external environment, as well as to the feline habits of sedentarism, that avoid significant cooling in these regions. This report highlights the importance of taking this type of occurrence into account when performing an epidural in the Siamese cat breed. Also, to avoid skin color change in this breed, the authors recommend a midline abdominal instead of a flank approach to perform OHE.

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