scholarly journals Croonian Lecture: The insect as a medium for the study of physiology

1948 ◽  
Vol 135 (881) ◽  
pp. 430-446 ◽  
Author(s):  
Vincent Brian Wigglesworth
Keyword(s):  
Mechanical Ventilation ◽  
Single Cell ◽  
The Other ◽  
Physiological Study ◽  
Functional Specialization ◽  
Air Sacs ◽  
Other Hand ◽  
Diffusion Of Gases

Insects live and feed, move, grow and multiply like other animals; but they are so varied in form, so rich in species, and adapted to such diverse conditions of life that they afford unrivalled opportunities for physiological study. The general problems of physiology are much the same in all groups of animals; and this lecture, which represents, in effect, an apology for the study of insect physi­ology, is an attempt to show that among the insects may be found material well suited for the solution of many of these problems. By human standards most insects are small in size, and this brings with it certain features which dominate their physiology. There is the same degree of functional specialization in their organs as there is in mammals; but they are made up of cells of the same dimensions as those in other animals—often, indeed, of cells which are larger than most. Each organ therefore contains far fewer cells, and the organization of their bodies must of necessity appear more simple. It is, however, a deceptive simplicity; for the range of physiological activities of which the single cell is capable is no less and may indeed be greater than it is in larger animals. On the other hand, their small size enables the insects to dispense with many of the physiological elaborations that are needed by mammals. Air-containing tracheae run direct to the tissues; and the high rates of metabolism which active insects develop can be met by the diffusion of gases along these tubes, supplemented in the most active forms by mechanical ventilation of the larger trunks or of the air sacs into which they are dilated.

scholarly journals Relevance of single cell and single molecule studies at different biological and physical length scales

2017 ◽  
Author(s):  
Wenfa Ng
Keyword(s):  
Quantum Mechanics ◽  
Single Cell ◽  
Single Molecule ◽  
Active Site ◽  
Covalent Bond ◽  
The Other ◽  
Quantum Mechanical ◽  
Microfluidic Channels ◽  
Other Hand ◽  
Single Molecule Studies

Scale transcends multiple levels of biological and physical organization, and is the critical factor that determines success of any scientific investigation. Specifically, the scale at which a question is posed plays a crucial role in influencing the type of experiments and apparatuses needed. Single cell and single molecule experiments came to the fore of experiment science due to its capability at addressing a fundamental problem in biology and physical science: does the same behavior in cells and molecules transcend different length and population scales? Thus far, single cell experiments could be achieved with trapping of single cell using optical tweezer traps and microfluidic channels. The same, however, is not true for single molecule studies, which remains in the realm of theoretical and simulation studies. Specifically, single molecule experiment remains at the hundreds to thousands of molecules level, where possible skew in the population of molecules sampled could provide a false depiction of molecular reality of a larger population. But, what do scientists learn from single cell and single molecule studies? Is it the uncovering of mysteries of the probabilistic behavior at the single entity level, guided by perhaps quantum mechanics? The answer is no for single cell studies, given that cellular decision making require the input of tens to hundreds of molecular sensors and effectors within a cell. Hence, single cell behavior is not random, but directed at a nutrient or concentration gradient or signaling source. On the other hand, enzymatic catalysis of a single molecule substrate with the active site involves a quantum mechanical crosstalk. Thus, reaction between the substrate molecule and the active site proceeds if suitable energy levels (i.e., quantum mechanical states) are found for both parties. Given that distribution of quantum mechanical states is probabilistic, stochasticity rules single molecule interaction such as a covalent bond formation reaction between reactant A and B. Thus, single cell and single molecule studies do hold relevance in biological and physical sciences research if the correct experiment tool is used for a pertinent question at an appropriate length and population scale. For example, while tremendous amount of basic understanding could be derived from single cell experiments, single cell perspective is not relevant to questions examining the interactions between two large subpopulations of cells. Single molecule experiments, on the other hand, remains in the theoretical and simulation realm for highlighting the effect of quantum mechanics in guiding the behavior of molecules at the nanoscale.

scholarly journals Relevance of single cell and single molecule studies at different biological and physical length scales

2017 ◽  
Author(s):  
Wenfa Ng
Keyword(s):  
Quantum Mechanics ◽  
Single Cell ◽  
Single Molecule ◽  
Active Site ◽  
Covalent Bond ◽  
The Other ◽  
Quantum Mechanical ◽  
Microfluidic Channels ◽  
Other Hand ◽  
Single Molecule Studies

Scale transcends multiple levels of biological and physical organization, and is the critical factor that determines success of any scientific investigation. Specifically, the scale at which a question is posed plays a crucial role in influencing the type of experiments and apparatuses needed. Single cell and single molecule experiments came to the fore of experiment science due to its capability at addressing a fundamental problem in biology and physical science: does the same behavior in cells and molecules transcend different length and population scales? Thus far, single cell experiments could be achieved with trapping of single cell using optical tweezer traps and microfluidic channels. The same, however, is not true for single molecule studies, which remains in the realm of theoretical and simulation studies. Specifically, single molecule experiment remains at the hundreds to thousands of molecules level, where possible skew in the population of molecules sampled could provide a false depiction of molecular reality of a larger population. But, what do scientists learn from single cell and single molecule studies? Is it the uncovering of mysteries of the probabilistic behavior at the single entity level, guided by perhaps quantum mechanics? The answer is no for single cell studies, given that cellular decision making require the input of tens to hundreds of molecular sensors and effectors within a cell. Hence, single cell behavior is not random, but directed at a nutrient or concentration gradient or signaling source. On the other hand, enzymatic catalysis of a single molecule substrate with the active site involves a quantum mechanical crosstalk. Thus, reaction between the substrate molecule and the active site proceeds if suitable energy levels (i.e., quantum mechanical states) are found for both parties. Given that distribution of quantum mechanical states is probabilistic, stochasticity rules single molecule interaction such as a covalent bond formation reaction between reactant A and B. Thus, single cell and single molecule studies do hold relevance in biological and physical sciences research if the correct experiment tool is used for a pertinent question at an appropriate length and population scale. For example, while tremendous amount of basic understanding could be derived from single cell experiments, single cell perspective is not relevant to questions examining the interactions between two large subpopulations of cells. Single molecule experiments, on the other hand, remains in the theoretical and simulation realm for highlighting the effect of quantum mechanics in guiding the behavior of molecules at the nanoscale.

scholarly journals Microcolony Formation by Single-Cell Synechococcus Strains as a Fast Response to UV Radiation

2011 ◽  
Vol 77 (21) ◽  
pp. 7533-7540 ◽  
Author(s):  
Cristiana Callieri ◽  
Andrea Lami ◽  
Roberto Bertoni
Keyword(s):  
Single Cell ◽  
Uv Radiation ◽  
Fast Response ◽  
The Other ◽  
Low Light ◽  
Content Type ◽  
Other Hand ◽  
Light Intensities ◽  
Group I ◽  
Group B

ABSTRACTUV radiation (UVR) has different effects on prokaryotic cells, such as, for instance, filamentation and aggregation in bacteria. Here we studied the effect of UVR on microcolony formation in two freshwaterSynechococcusstrains of different ribotypes (group B and group I) and phycobiliprotein compositions (phycoerythrin [PE] and phycocyanin [PC]). Each strain was photoacclimated at two light intensities, low light (LL) (10 μmol m−2s−1) and moderate light (ML) (100 μmol m−2s−1). The cultures were exposed for 6 days to treatments with UVR or without UVR. PE-richSynechococcusacclimated to LL had a low carotenoid/chlorophylla(car/chl) ratio but responded faster to UVR treatment, producing the highest percentages of microcolonies and of cells in microcolonies. Conversely, the same strain acclimated to ML, with a higher car/chl ratio, did not aggregate significantly. These results suggest that microcolony formation by PE-richSynechococcusis induced by UVR if carotenoid levels are low. PC-richSynechococcusformed a very low percentage of microcolonies in both acclimations even with low car/chl ratio. The different responses of the twoSynechococcusstrains to UVR depend on their pigment compositions. On the other hand, this study does not exclude that UVR-induced microcolony formation could also be related to specific ribotypes.

scholarly journals On the occurrence of lateral openings and fossae (pleurocoels) in the thoracic vertebrae of neornithine birds and their functional significance

2021 ◽  
Vol 71 ◽  
pp. 453-463
Author(s):  
Gerald Mayr
Keyword(s):  
Vertebral Body ◽  
Functional Significance ◽  
Inverse Correlation ◽  
The Other ◽  
Thoracic Vertebrae ◽  
Pulmonary System ◽  
Air Sacs ◽  
Other Hand ◽  
Functional Aspects ◽  
Structural Resistance

Abstract The occurrence of lateral openings and pleurocoels (lateral fossae) in the corpus of the thoracic vertebrae of extant and fossil neornithine birds is reviewed, with both features having been identified as osteological correlates of the avian pulmonary system. Openings mainly occur in larger species with a high overall bone pneumatization but do not seem to serve for the passage of lung or air sac diverticula. Pleurocoels, on the other hand, are not directly related to pneumatic features and constitute a plesiomorphic trait that was widespread in Mesozoic non-neornithine birds. It is noted that an inverse correlation exists between the occurrence of pleurocoels and the pneumatization of the humerus, with pleurocoels being mainly found in extant and fossil taxa, in which the humerus is not pneumatized by diverticula of the clavicular air sac. Here it is hypothesized that pleurocoels primarily serve to increase the structural resistance of the vertebral body and were reduced multiple times in neornithine birds. In some taxa, their reduction may be related to the development of the furcula, which assists ventilation of the clavicular and cervical air sacs and may thereby contribute to the pneumatization of both, the humerus and the thoracic vertebrae. If so, Mesozoic non-neornithine birds, which had a rigid furcula with massive shafts as well as non-pneumatic humeri and pronounced pleurocoels, are likely to have differed in functional aspects of their air sac system from extant birds.

scholarly journals Review \ COVID- 19 Pandemic: The Implications for Diabetes Care  and Specifics Management: مراجعة/ جائحة كوفيد- 19: الآثار المترتبة على رعاية مرضى السكري والمعالجة الخاصة

2020 ◽  
Vol 4 (3) ◽  
Author(s):  
Mohammed Sadeg A. Al- Awar, Talal Ali H. Al- Qalah, Ammar S.
Keyword(s):  
Mechanical Ventilation ◽  
Risk Factor ◽  
Invasive Mechanical Ventilation ◽  
Current Data ◽  
The Other ◽  
Blood Glucose Monitoring ◽  
Diabetic Patients ◽  
Prognostic Impact ◽  
Other Hand ◽  
Increased Risk

Background. The coronavirus disease 2019 (COVID- 19) pandemic has emerged as one of the greatest challenges faced by humankind in the recent past. People with diabetes and related comorbidities are at increased risk of its complications and of COVID- 19- related death. Older age, multimorbidity, hyperglycemia, cardiac injury and severe inflammatory response are predictors of poor outcome. Aims. This article summarizes current data on the clinical presentation and risks of COVID- 19 in diabetic patients. We also provide some recommendations for the management of diabetic patients with COVID- 19. Results: According. to current data, diabetic patients do not appear to be at increased risk of contracting SARS- CoV- 2 compared to the general population. On the other hand, diabetes is a risk factor for developing severe and critical forms of COVID- 19, the latter requiring admission to an intensive care unit and/or use of invasive mechanical ventilation, with high mortality rates. The characteristics of diabetic patients at risk for developing severe and critical forms of COVID- 19, as well as the prognostic impact of diabetes on the course of COVID- 19, are under current investigation. Obesity, the main risk factor for incident type 2diabetes, is more common in patients with critical forms of COVID- 19 requiring invasive mechanical ventilation. On the other hand, COVID- 19 is usually associated with poor glycemic control and a higher risk of ketoacidosis in diabetic patients. There are currently no recommendations in favour of discontinuing antihypertensive medications that interact with the renin-angiotensin-aldosterone system. Metformin and Sodium-glucose transport protein- 2)SGLT2( inhibitors should be discontinued in patients with severe forms of COVID- 19 owing to the risks of lactic acidosis and ketoacidosis. Conclusion: There are currently no data showing an increased risk of contracting COVID- 19 in diabetic patients. On the other hand, diabetic patients require special attention, since diabetes is associated with a higher risk of severe, critical, and fatal forms of COVID- 19. Our knowledge about this new Coronavirus progresses day by day. Ongoing studies will make it possible to better define the profile(s) of diabetic patients at increased risk of poor prognosis. In any case, the importance of blood glucose monitoring and control over the course of the infection should be emphasized, as well as that of screening for (pre) diabetes in all patients with a confirmed infection by COVID- 19.

A study of cometary eruptions through OH radio-lines

1999 ◽  
Vol 173 ◽  
pp. 249-254
Author(s):  
A.M. Silva ◽  
R.D. Miró
Keyword(s):  
Short Duration ◽  
Growth Curves ◽  
The Other ◽  
Initial Mass ◽  
Radio Lines ◽  
Other Hand ◽  
Sudden Rise

AbstractWe have developed a model for theH2OandOHevolution in a comet outburst, assuming that together with the gas, a distribution of icy grains is ejected. With an initial mass of icy grains of 108kg released, theH2OandOHproductions are increased up to a factor two, and the growth curves change drastically in the first two days. The model is applied to eruptions detected in theOHradio monitorings and fits well with the slow variations in the flux. On the other hand, several events of short duration appear, consisting of a sudden rise ofOHflux, followed by a sudden decay on the second day. These apparent short bursts are frequently found as precursors of a more durable eruption. We suggest that both of them are part of a unique eruption, and that the sudden decay is due to collisions that de-excite theOHmaser, when it reaches the Cometopause region located at 1.35 × 105kmfrom the nucleus.

Closing the GAP—A 5Å Scanning Microscope

1969 ◽  
Vol 27 ◽  
pp. 6-7
Author(s):  
A. V. Crewe
Keyword(s):  
Normal Form ◽  
The Other ◽  
Resolving Power ◽  
Scanning Microscope ◽  
Conventional Microscope ◽  
Other Hand ◽  
Closing The Gap ◽  
Thermal Sources ◽  
Better Than ◽  
Transmission Microscope

We have become accustomed to differentiating between the scanning microscope and the conventional transmission microscope according to the resolving power which the two instruments offer. The conventional microscope is capable of a point resolution of a few angstroms and line resolutions of periodic objects of about 1Å. On the other hand, the scanning microscope, in its normal form, is not ordinarily capable of a point resolution better than 100Å. Upon examining reasons for the 100Å limitation, it becomes clear that this is based more on tradition than reason, and in particular, it is a condition imposed upon the microscope by adherence to thermal sources of electrons.

Life Beyond 1MeV

1980 ◽  
Vol 38 ◽  
pp. 30-33
Author(s):  
K.H. Westmacott
Keyword(s):  
Electron Microscopy ◽  
Past Experience ◽  
The Other ◽  
Good Case ◽  
Other Hand ◽  
The U.S

Life beyond 1MeV – like life after 40 – is not too different unless one takes advantage of past experience and is receptive to new opportunities. At first glance, the returns on performing electron microscopy at voltages greater than 1MeV diminish rather rapidly as the curves which describe the well-known advantages of HVEM often tend towards saturation. However, in a country with a significant HVEM capability, a good case can be made for investing in instruments with a range of maximum accelerating voltages. In this regard, the 1.5MeV KRATOS HVEM being installed in Berkeley will complement the other 650KeV, 1MeV, and 1.2MeV instruments currently operating in the U.S. One other consideration suggests that 1.5MeV is an optimum voltage machine – Its additional advantages may be purchased for not much more than a 1MeV instrument. On the other hand, the 3MeV HVEM's which seem to be operated at 2MeV maximum, are much more expensive.

Can the Academic Self-Concept be Positive and Realistic?

2005 ◽  
Vol 19 (3) ◽  
pp. 129-132 ◽  
Author(s):  
Reimer Kornmann
Keyword(s):  
Academic Performance ◽  
Opposite Effect ◽  
Self Esteem ◽  
Point Of View ◽  
The Other ◽  
Self Concept ◽  
High Ability ◽  
Self Image ◽  
Other Hand

Summary: My comment is basically restricted to the situation in which less-able students find themselves and refers only to literature in German. From this point of view I am basically able to confirm Marsh's results. It must, however, be said that with less-able pupils the opposite effect can be found: Levels of self-esteem in these pupils are raised, at least temporarily, by separate instruction, academic performance however drops; combined instruction, on the other hand, leads to improved academic performance, while levels of self-esteem drop. Apparently, the positive self-image of less-able pupils who receive separate instruction does not bring about the potential enhancement of academic performance one might expect from high-ability pupils receiving separate instruction. To resolve the dilemma, it is proposed that individual progress in learning be accentuated, and that comparisons with others be dispensed with. This fosters a self-image that can in equal measure be realistic and optimistic.

Stories and the Self

2020 ◽  
Vol 32 (2) ◽  
pp. 47-58 ◽  
Author(s):  
Stefan Krause ◽  
Markus Appel
Keyword(s):  
Meta Analysis ◽  
The Self ◽  
The Other ◽  
Lower Degree ◽  
Contrast Effects ◽  
Self Perception ◽  
Self Perceptions ◽  
Other Hand ◽  
The One ◽  
Implicit And Explicit

Abstract. Two experiments examined the influence of stories on recipients’ self-perceptions. Extending prior theory and research, our focus was on assimilation effects (i.e., changes in self-perception in line with a protagonist’s traits) as well as on contrast effects (i.e., changes in self-perception in contrast to a protagonist’s traits). In Experiment 1 ( N = 113), implicit and explicit conscientiousness were assessed after participants read a story about either a diligent or a negligent student. Moderation analyses showed that highly transported participants and participants with lower counterarguing scores assimilate the depicted traits of a story protagonist, as indicated by explicit, self-reported conscientiousness ratings. Participants, who were more critical toward a story (i.e., higher counterarguing) and with a lower degree of transportation, showed contrast effects. In Experiment 2 ( N = 103), we manipulated transportation and counterarguing, but we could not identify an effect on participants’ self-ascribed level of conscientiousness. A mini meta-analysis across both experiments revealed significant positive overall associations between transportation and counterarguing on the one hand and story-consistent self-reported conscientiousness on the other hand.

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