The Sensory Physiology of the Harvest Mite Trombicula Autumnalis Shaw

1950 ◽  
Vol 27 (3) ◽  
pp. 461-494
Author(s):  
B. M. JONES
Keyword(s):  
Light Intensity ◽  
Natural Environment ◽  
Free Water ◽  
The Body ◽  
Quiescent State ◽  
Sensory Physiology ◽  
Linear Gradient ◽  
Dry Air ◽  
Sudden Decrease ◽  
Heated Object

Responses to stimuli Light. In a strong beam of light the harvest mite will move directly towards the source, whereas in a weak light the tracks are at first inclined to be wavy, but as they approach the source the tracks straighten. The mite moves along the bisector of two intersecting lights of equal intensity, and when blinded on one side makes circus movements. When offered a linear gradient of light intensity the mite avoids the darkened portion and moves towards the lightest part of the field. Its movement towards sunlight is a true response to light and not to heat. A sudden decrease of light intensity produces a questing response. Temperature. The sensory perception of heat is poorly developed. The mite is incapable of locating a warm tube or the body of a young live mouse. On touching a heated object it displays a well-defined response to a temperature difference of about 15° C. In a linear or concentric temperature gradient it displays avoiding reactions to low and high temperatures and appears to prefer a range extending from 15 to 26° C. Chemical stimulation. The mite is repelled at a distance of 0.5 cm. from phenol, methyl phthalate, dilute ammonia, xylene and a 3 % solution of glacial acetic acid. Toluene was repugnant at 1.5 cm., whilst a mixture of amyl acetate and water repelled the mite at 5 cm. Complete indifference was shown to the odour of skin, liver, sebum and cerumen, but perspiration induced an avoiding reaction. Humidity. Depletion of the water content influences the response of the mite to humidity. A desiccated mite is active in dry air and inactive in moist air, but a normal individual will settle in either moist or dry air, while avoiding saturated air. The mite requires high humidities for prolonged survival, but avoids free water. Touch. Unfed mites are very sensitive to touch. The extent of stimulation by contact with each other's bodies, which is regarded as high, immobilizes them, and it is primarily responsible for the quiescent state of a cluster of mites. When the stimulation is low, for example, when only the tarsi are in contact with a surface, the mite responds by displaying a high state of activity. A mite lightly touched will immediately quest, a response induced equally by vibrations of the substratum. Clustering The gregarious habit of the mites is primarily a response to the touch of each other's bodies. When the humidity is within the range 95-100% R.H. light will induce the mites to climb up a rod and form a cluster at the tip. Whether or not negative geotaxis also plays a part, it is difficult to say, because the evidence suggested that the mite is independent of gravity. Sense organs There are three types of sensilla: (1) tactile sensilla, both plumose and plain; (2) peg organs; (3) minute sensory rods, principally confined to the first leg. An elliptical lens, a discoid mass of red-pigmented oily substance, and a pronounced dark pigmented cup are conspicuous features of the better developed anterior eye of each ocular area. Identification of the responses Where possible the responses of the mite to various kinds of stimuli have been identified according to a recognized scheme of classification. Behaviour in the natural environment The responses to stimuli which the mite will encounter in the natural environment, and their value with respect to acquiring a host, are discussed.

The sensory physiology of the human louse Pediculus humanus corporis de Geer (Anoplura)

Parasitology ◽  
1941 ◽  
Vol 33 (1) ◽  
pp. 67-109 ◽  
Author(s):  
V. B. Wigglesworth
Keyword(s):  
Light Intensity ◽  
Air Temperature ◽  
Bright Light ◽  
Radiant Heat ◽  
The Body ◽  
Moist Air ◽  
Sensory Physiology ◽  
Linear Gradient ◽  
Pediculus Humanus ◽  
Sensory Responses

(i) Sensory responsesThe reactions of the body louse to temperature, humidity, smell, contact and light have been tested in an arena divided into two halves.Temperature. A temperature of 29–30° C. is preferred before 32° C. or 27° C. As the alternative temperature rises above 32° C. or falls below 27° C. the avoidance becomes increasingly strong. Different individuals vary in sensitivity.These results are in accordance with those observed in a linear gradient of temperature, in which the lice collect chiefly in the region from 28 to 31° C.The response is always to air temperature; there is no response to radiant heat from objects at 20–45° C.Humidity. The louse is generally indifferent to humidity over the range from 10 to 60 or 75% r.h. Higher humidities are avoided. But when offered two humidities the choice is greatly influenced by the conditions experienced by the louse in the immediate past; it avoids any change; hence different individuals may show quite different responses. Moreover, when offered the choice of very moist air (95 % r.h. or over) and very dry (47 % r.h. or under) the louse becomes more readily adapted to the moist air and begins to avoid the dry.Smell. The louse prefers cloth that has been in contact with human skin to clean cloth or cloth smelling of dog or rabbit. The smell of other lice and of their excreta is also attractive. Many substances serve as repellents; a refined petroleum with a very faint odour has been chiefly used for the experiments.Contact. When offered smooth and rough materials the louse chooses the latter. It moves more rapidly on smooth materials and does not come to rest so readily. It shows little response to air currents unless very strong, when they are avoided.Light. The movements of the louse are arrested or retarded by sudden exposure to a bright light, and sometimes it may show avoiding movements. But the movement of the louse towards dark places is mainly a response to directed light received by the horizontally placed eyes. Slight differences in the light received from different directions exert a much greater effect if the louse is exposed to a low level of general light intensity.The movement of the louse towards relatively small dark objects is probably a manifestation of the same response.

scholarly journals On The Verge of the Hybrid Mind

2021 ◽  
Vol 1 (1) ◽  
pp. 30-43
Author(s):  
Surjo Soekadar ◽  
Jennifer Chandler ◽  
Marcello Ienca ◽  
Christoph Bublitz
Keyword(s):  
Human Brain ◽  
Natural Environment ◽  
The Body ◽  
The Self ◽  
Cognitive Systems ◽  
Privacy And Security ◽  
Technological Artifacts ◽  
Mind And Body ◽  
The Mind ◽  
The Brain

Recent advances in neurotechnology allow for an increasingly tight integration of the human brain and mind with artificial cognitive systems, blending persons with technologies and creating an assemblage that we call a hybrid mind. In some ways the mind has always been a hybrid, emerging from the interaction of biology, culture (including technological artifacts) and the natural environment. However, with the emergence of neurotechnologies enabling bidirectional flows of information between the brain and AI-enabled devices, integrated into mutually adaptive assemblages, we have arrived at a point where the specific examination of this new instantiation of the hybrid mind is essential. Among the critical questions raised by this development are the effects of these devices on the user’s perception of the self, and on the user’s experience of their own mental contents. Questions arise related to the boundaries of the mind and body and whether the hardware and software that are functionally integrated with the body and mind are to be viewed as parts of the person or separate artifacts subject to different legal treatment. Other questions relate to how to attribute responsibility for actions taken as a result of the operations of a hybrid mind, as well as how to settle questions of the privacy and security of information generated and retained within a hybrid mind.

Uptake of Zinc by the Aquatic Larvae of Simulium ornatipes (Diptera : Nematocera)

1978 ◽  
Vol 29 (3) ◽  
pp. 299 ◽  
Author(s):  
JGT Carter ◽  
WL Nicholas
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Free Water ◽  
Weight Fraction ◽  
The Body ◽  
Ion Concentration ◽  
High Molecular Weight Fraction ◽  
Phosphonic Acids ◽  
Calcium Ion Concentration ◽  
Molecular Weight Fractions

The uptake and loss of zinc by the aquatic larvae of the blackfly S. ornatipes was investigated using radioactive 65Zn. Larvae may absorb significant quantities of zinc from solution, and a substantial proportion remains in the body when larvae are transferred to zinc-free water. Uptake is assisted by metabolism, but an increase of the calcium ion concentration, although reducing toxicity, has no effect on uptake, exchange or the loss of zinc. Larvae may be fractionated into 'cuticle', 'high-' and 'low-molecular-weight' fractions, based on solubility in water and 80% (v/v) ethanol. In the cuticle and high-molecular-weight fractions two 'pools' may be identified by dialysis against Na3EDTA -a pool in which zinc is weakly held and exchanges rapidly with the zinc in solution, and one where zinc is held and exchanges slowly. Exposure time, temperature, and external concentration influence the quantity of zinc entering these pools. Washing the cuticle and high-molecular-weight fractions with a series of buffers suggests that zinc is bound by phenolic groups in the cuticle fraction, and by phosphonic acids in the high-molecular-weight fraction. Sulfhydryl groups did not bind a major portion of the zinc.

scholarly journals The Role of Breast Cancer Stem Cells as a Prognostic Marker and a Target to Improve the Efficacy of Breast Cancer Therapy

Cancers ◽  
2019 ◽  
Vol 11 (7) ◽  
pp. 1021 ◽  
Author(s):  
Maria Giovanna Scioli ◽  
Gabriele Storti ◽  
Federico D’Amico ◽  
Pietro Gentile ◽  
Giulia Fabbri ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Stem Cells ◽  
Cancer Stem Cells ◽  
Tumor Cells ◽  
The Body ◽  
Cell Subpopulation ◽  
Phenotypic Characterization ◽  
Quiescent State ◽  
Breast Cancer Stem Cells ◽  
Mesenchymal Transition

Breast cancer is the most common form of tumor in women and the leading cause of cancer-related mortality. Even though the major cellular burden in breast cancer is constituted by the so-called bulk tumor cells, another cell subpopulation named cancer stem cells (CSCs) has been identified. The latter have stem features, a self-renewal capacity, and the ability to regenerate the bulk tumor cells. CSCs have been described in several cancer types but breast cancer stem cells (BCSCs) were among the first to be identified and characterized. Therefore, many efforts have been put into the phenotypic characterization of BCSCs and the study of their potential as prognostic indicators and therapeutic targets. Many dysregulated pathways in BCSCs are involved in the epithelial–mesenchymal transition (EMT) and are found up-regulated in circulating tumor cells (CTCs), another important cancer cell subpopulation, that shed into the vasculature and disseminate along the body to give metastases. Conventional therapies fail at eliminating BCSCs because of their quiescent state that gives them therapy resistance. Based on this evidence, preclinical studies and clinical trials have tried to establish novel therapeutic regimens aiming to eradicate BCSCs. Markers useful for BCSC identification could also be possible therapeutic methods against BCSCs. New approaches in drug delivery combined with gene targeting, immunomodulatory, and cell-based therapies could be promising tools for developing effective CSC-targeted drugs against breast cancer.

Shift in body fluid compartments after dehydration in humans

1988 ◽  
Vol 65 (1) ◽  
pp. 318-324 ◽  
Author(s):  
H. Nose ◽  
G. W. Mack ◽  
X. R. Shi ◽  
E. R. Nadel
Keyword(s):  
Body Fluid ◽  
Extracellular Fluid ◽  
Plasma Osmolality ◽  
Free Water ◽  
Inverse Correlation ◽  
The Body ◽  
Free Water Clearance ◽  
Before And After ◽  
Body Fluid Compartments ◽  
Fluid Compartments

To investigate the influence of [Na+] in sweat on the distribution of body water during dehydration, we studied 10 volunteer subjects who exercised (40% of maximal aerobic power) in the heat [36 degrees C, less than 30% relative humidity (rh)] for 90-110 min to produce a dehydration of 2.3% body wt (delta TW). After dehydration, the subjects rested for 1 h in a thermoneutral environment (28 degrees C, less than 30% rh), after which time the changes in the body fluid compartments were assessed. We measured plasma volume, plasma osmolality, and [Na+], [K+], and [Cl-] in plasma, together with sweat and urine volumes and their ionic concentrations before and after dehydration. The change in the extracellular fluid space (delta ECF) was estimated from chloride distribution and the change in the intracellular fluid space (delta ICF) was calculated by subtracting delta ECF from delta TW. The decrease in the ICF space was correlated with the increase in plasma osmolality (r = -0.74, P less than 0.02). The increase in plasma osmolality was a function of the loss of free water (delta FW), estimated from the equation delta FW = delta TW - (loss of osmotically active substance in sweat and urine)/(control plasma osmolality) (r = -0.79, P less than 0.01). Free water loss, which is analogous to "free water clearance" in renal function, showed a strongly inverse correlation with [Na+] in sweat (r = -0.97, P less than 0.001). Fluid movement out of the ICF space attenuated the decrease in the ECF space.(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals Hematopoietic Stem Cell Development, Niches, and Signaling Pathways

2012 ◽  
Vol 2012 ◽  
pp. 1-16 ◽  
Author(s):  
Kamonnaree Chotinantakul ◽  
Wilairat Leeanansaksiri
Keyword(s):  
Stem Cell ◽  
Signaling Pathways ◽  
Cell Biology ◽  
The Body ◽  
Basic Knowledge ◽  
Stem Cell Biology ◽  
Quiescent State ◽  
Hematopoietic Stem ◽  
Medicine Development ◽  
Biology Research

Hematopoietic stem cells (HSCs) play a key role in hematopoietic system that functions mainly in homeostasis and immune response. HSCs transplantation has been applied for the treatment of several diseases. However, HSCs persist in the small quantity within the body, mostly in the quiescent state. Understanding the basic knowledge of HSCs is useful for stem cell biology research and therapeutic medicine development. Thus, this paper emphasizes on HSC origin, source, development, the niche, and signaling pathways which support HSC maintenance and balance between self-renewal and proliferation which will be useful for the advancement of HSC expansion and transplantation in the future.

Studies on the growth and longevity of the yellow-bellied toad, Bombina variegata, in natural environments

1993 ◽  
Vol 14 (1) ◽  
pp. 35-44 ◽  
Author(s):  
Barbara Plytycz ◽  
Janusz Bigaj
Keyword(s):  
Body Size ◽  
Body Length ◽  
Cross Sections ◽  
Natural Environment ◽  
Early Life ◽  
Dorsal Surface ◽  
The Body ◽  
Natural Environments ◽  
Bombina Variegata ◽  
Different Parts

AbstractYellow-bellied toads were studied in their natural environment in a mountain locality in southeastern Poland. 608 specimens were captured, marked by yellow skin autografts placed in different parts of their dorsal surface according to body length, and released. Some of them were recaptured and measured from one to nine years later to estimate their growth and longevity. Yellow-bellied toads grew rapidly in early life; thereafter their growth was very limited. Body size was not an accurate age indicator of an individual of this species. The body length 51-55 mm was maximal in this locality. Yellow-bellied toads were long-lived in nature, some individuals surviving for much more than ten years, and perhaps even more than 20 years. The skeletochronological technique (counting the growth lines in phalangeal cross-sections of the clipped toes of some marked individuals) underestimated the actual age of these animals.

Convective instability by active stress

1969 ◽  
Vol 310 (1501) ◽  
pp. 183-219 ◽  
Keyword(s):  
Convective Instability ◽  
Pure Shear ◽  
Fluid Motion ◽  
Transformation Process ◽  
The Body ◽  
Equivalent Transformation ◽  
Quiescent State ◽  
Concentration Gradients ◽  
Active Stress ◽  
The Galerkin Method

Composition-dependent stress fields in continuous and mechanically isolated material can, it is shown, initiate and maintain conversion of chemical to kinetic energy. Though the process is analogous to natural convection, neither the body force of the well-known buoyancy mechanism nor the singular inhomogeneity and anisotropy of the interfacial tension mechanism is required. In the cases examined, the material is represented by the constitutive relation for incompressible Newtonian fluid augmented by an active stress which must be anisotropic or nonlinear in concentration gradients (or other, equivalent gradients) in accordance with the oft-misquoted Curie principle. The concentration gradients are supposed to be sustained by steady chemical reaction (or an equivalent transformation process) throughout the material and by exchange with surroundings. Conventional linear analysis of asymptotic stability is used to identify types of stress/concentration-gradient coupling that can render a quiescent state of reaction and diffusion unstable when concentration gradients exceed critical values. It is found that both deviatoric (pure shear) and antisymmetric active stress can support two-dimensional convective instability in a cylinder of material in which the quiescent state is circularly symmetric. Certain cases of stationary instability are solved exactly. Others involving both stationary and oscillatory instability are treated by a new version of the Galerkin method. The results establish the possibility of generating fluid motion by mechanochemical means in continuous material having appropriate subcontinuum structure. Whatever their relevance to protoplasmic movement in biological systems they do contain challenges for experimental and theoretical fluid mechanics and related areas of rheology and chemistry.

Application of a Boundary Element Method for Wave-Body Interaction Problems Considering the Non-Linear Water Surface

2017 ◽  
Author(s):  
Daniel Ferreira González ◽  
Jonas Bechthold ◽  
Moustafa Abdel-Maksoud
Keyword(s):  
Water Surface ◽  
Three Dimensional ◽  
Free Water ◽  
Numerical Approach ◽  
Panel Method ◽  
The Body ◽  
Time Step ◽  
Non Linear ◽  
Wigley Hull ◽  
Tank Test

In this paper an existing time domain panel method, which was originally developed for propeller flow simulations, is extended by implementing the mixed Eulerian-Lagrangian approach for the computation of the non-linear free water surface. The three-dimensional panel method uses a constant source and doublet density distribution on each panel and a Dirichlet boundary condition to solve the velocity potential in every time step. Additionally, a formulation for the acceleration potential is included in order to determine the hydrodynamic forces accurately. The paper gives an overview on the governing equations and introduces the numerical approach. Validation results of the developed method are presented for the wave resistance of a submerged spheroid and a wigley hull. Additionally, the wave diffraction due to a surface piercing cylinder in regular waves is validated regarding the forces and the water surface elevation around the body. Here, the computations are compared with other numerical methods as well as tank test results. Apart from this, the paper deals with an application example showing simulations of an artificial service vessel catamaran in waves. The forces on the hull with and without forward speed are presented. The paper concludes with a discussion of the presented results and a brief outlook on further work.

scholarly journals The Influence of Cold Atmospheric Air on the Environmental Health of Sportsman

2018 ◽  
Keyword(s):  
Respiratory Tract ◽  
Natural Environment ◽  
Negative Impact ◽  
Negative Influence ◽  
Modern Human ◽  
The Body ◽  
Sporting Events ◽  
Cold Environment ◽  
Ecological Health ◽  
Atmospheric Air

On the basis of a systematic analysis of the scientific literature, it was found that the increased sensitivity of a modern human being to the negative effects of the cold natural environment is due to its passage from the shrouds of East Africa with characteristic high ambient temperatures, primarily atmospheric air. At the same time, in comparative terms, the extinct Neanderthal, with his Eurasian apprehension in the conditions of glacial periods, was on the contrary sufficiently well adapted to the cold environment. The subsequent adaptation of a modern human type at the genetic level with the formation of the main races (Caucasoid, Negroid, Mongoloid) could not sufficiently compensate for its insufficient resistance to the cold environment. According to the results of the research, the main ways of solving the problem of the negative influence of the cold natural environment on the ecological health of athletes were determined: the rationing of the order of sporting activities of athletes depending on the degree of low-temperature environment, diagnosing the athletes' hypersensitivity of the respiratory tract to cold atmospheric air, degree of tension of the processes of thermoregulation of the body. The conclusions are drawn according to which the prevention of the negative impact of extreme conditions of the cold environment (primarily cold atmospheric air) on the ecological health of athletes should be systemic, integrated. The system of preventive measures should include an early diagnosis of the development of airway hyperresponsiveness of athletes to the effects of cold atmospheric air, as well as an assessment of the degree of tension of the body's thermoregulatory system to the effect of cold. In the system of preventing the negative impact of the cold environment on the body of athletes engaged in winter sports in the open space, it is necessary to include regulation (normalization) of the temperature regime of cold atmospheric air when determining the possibility of holding sporting events. If necessary (the presence of hypersensitivity of the airways to the action of cold atmospheric air), it is advisable to use special means of protecting the respiratory tract of athletes from the negative influence of cold atmospheric air.

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