The function of olfactory input in pigeon orientation: does it provide navigational information or play another role?

1996 ◽  
Vol 199 (1) ◽  
pp. 113-119 ◽  
Author(s):  
R Wiltschko
Keyword(s):  
Meteorological Data ◽  
Olfactory Orientation ◽  
Navigational Cues ◽  
Homing Performance ◽  
Olfactory Input ◽  
Series Of Experiments

In 1972, Papi and his colleagues reported that anosmic pigeons were severely impaired in orientation and homing performance. This observation was followed up in a series of experiments involving numerous elaborate experimental manipulations. On the basis of their results, the hypothesis of olfactory navigation was proposed. Attempts to replicate these findings at other lofts produced widely differing effects, which suggested a highly variable role of olfaction. However, meteorological data, as well as certain other aspects of the findings, throw doubt on the role of odours as navigational cues. (1) Odours of the required characteristics and distribution do not seem to exist. (2) Some effects of 'olfactory' manipulations do not seem to depend on the availability of odours. (3) Olfactory treatments proved mostly effective, but often the effect was not as predicted. In view of these findings, explanations other than olfactory orientation cannot be excluded; accepting olfactory input as navigational information seems premature. Some of the findings are in agreement with the assumption that olfactory manipulations impair the birds' general processing and integration of information in some unknown way.

Nitric oxide decreases lung liquid production via guanosine 3′,5′-cyclic monophosphate

2001 ◽  
Vol 280 (5) ◽  
pp. L923-L929 ◽  
Author(s):  
James J. Cummings ◽  
Huamei Wang
Keyword(s):  
Nitric Oxide ◽  
Pulmonary Epithelium ◽  
Fetal Sheep ◽  
Cgmp Analog ◽  
Pulmonary Arterial ◽  
Series Of Experiments ◽  
Lung Liquid ◽  
Tracer Dilution ◽  
Induced Changes

We studied the role of cGMP in nitric oxide (NO)-induced changes in lung liquid production ( J v ) in chronically instrumented fetal sheep. Forty-five studies were done in which J v was measured by a tracer dilution technique. Left pulmonary arterial flow (Qlpa) was measured by a Doppler flow probe. There were two series of experiments. In the first, we gave 8-bromo-cGMP, a cGMP analog, by either the pulmonary vascular or intraluminal route; in the second, we used agents to inhibit or enhance endogenous cGMP activity. When infused directly into the pulmonary circulation, 8-bromo-cGMP significantly increased Qlpa but had no effect on J v. Conversely, when instilled into the lung liquid, 8-bromo-cGMP had no effect on Qlpa but significantly reduced J v. Inhibition of guanylate cyclase activity with methylene blue totally blocked, whereas phosphodiesterase inhibition with Zaprinast significantly enhanced, the effect of instilled NO on J v. Thus the reduction in lung liquid caused by NO appears to be mediated by cGMP, perhaps through a direct effect on the pulmonary epithelium.

The Role of Cutter Eccentricity on Surface Finish and Milling Forces

2004 ◽  
Author(s):  
Tony L. Schmitz ◽  
Jeremiah Couey ◽  
Eric Marsh ◽  
Michael F. Tummond
Keyword(s):  
Surface Finish ◽  
Milling Machine ◽  
Time Domain Simulation ◽  
Machined Surface ◽  
Premature Failure ◽  
Series Of Experiments ◽  
Error Motion ◽  
Milling Forces ◽  
Chip Load

In this paper, the role of milling cutter eccentricity, commonly referred to as runout, is explored to determine its effects on surface topography and milling forces. This work is motivated by the observation that commercially-available cutter bodies often exhibit variation in the teeth/insert radial locations as a result of manufacturing issues. Consequently, the chip load on individual cutting teeth varies periodically, which can lead to premature failure of the cutting edges. Additionally, this chip load variation increases the roughness of machined surfaces. This research isolates the effect of runout on cutting forces and the machined surface finish in a series of experiments completed on a precision milling machine with 0.1 μm positioning repeatability and 0.02 μm spindle error motion. The runout is varied in a controlled fashion and results compared between experiment and a comprehensive time-domain simulation.

Beaumont's Contribution to Gastric Psychophysiology: A Reappraisal

1988 ◽  
Vol 33 (7) ◽  
pp. 650-653 ◽  
Author(s):  
François M. Mai
Keyword(s):  
Gastric Emptying ◽  
Delayed Gastric Emptying ◽  
Bile Reflux ◽  
Emotional Arousal ◽  
Gastric Fistula ◽  
Physiological Changes ◽  
Digestive Process ◽  
Psychophysiological Research ◽  
Series Of Experiments

William Beaumont's monograph on the physiology of digestion which was first published in 1833, has become a classic in its field. In a series of experiments over a 10 year period on Alexis St. Martin, a 19 year old Canadian voyageur with a traumatic gastric fistula, Beaumont was the first to describe many important aspects of the digestive process. In two of the 238 experiments Beaumont noted gastric physiological changes induced by emotional arousal, these being bile reflux and delayed gastric emptying. Elsewhere in the book, but not in experimental context, Beaumont referred to non-specific changes in coloration and secretion of the mucous membrane induced by emotion. Modern gastric psychophysiological research has shown that emotional arousal increases, and withdrawal decreases, gastric acid secretion. It has also been shown conclusively that emotion can cause a reflux of bile into the stomach and it may delay gastric emptying. Although the main thrust of Beaumont's work was physiological, he must be credited with being the first investigator to draw attention to the role of emotional arousal in the digestive process.

κ- but not δ-opioid receptors mediate effects of ischemic preconditioning on both infarct and arrhythmia in rats

2001 ◽  
Vol 280 (1) ◽  
pp. H384-H391 ◽  
Author(s):  
Guan-Ying Wang ◽  
Song Wu ◽  
Jian-Ming Pei ◽  
Xiao-Chun Yu ◽  
Tak-Ming Wong
Keyword(s):  
Infarct Size ◽  
Opioid Receptors ◽  
Ischemic Preconditioning ◽  
Antiarrhythmic Action ◽  
Perfused Rat Heart ◽  
Calphostin C ◽  
Kinase C ◽  
Series Of Experiments ◽  
Pkc Inhibitors

Two series of experiments were performed in the isolated perfused rat heart to determine the role of κ- and δ-opioid receptors (OR) in cardioprotection of ischemic preconditioning (IP). In the first series of experiments, it was found that IP with two cycles of 5-min regional ischemia followed by 5-min reperfusion each reduced infarct size induced by 30-min ischemia, and the ameliorating effect of IP on infarct was attenuated with blockade of either 5 × 10−6 mol/l nor-binaltorphimine (nor-BNI), a selective κ-OR antagonist, or 5 × 10−6 mol/l naltrindole (NTD), a selective δ-OR antagonist. The second series showed that U50,488H, a selective κ-OR agonist, ord-Ala2-d-leu5-enkephalin (DADLE), a selective δ-OR agonist, dose dependently reduced the infarct size induced by ischemia, which mimicked the effects of IP. The effect of 10−5 mol/l U50,488H on infarct was significantly attenuated by blockade of protein kinase C (PKC) with specific PKC inhibitors, 5 × 10−6 mol/l chelerythrine or 8 × 10−7 mol/l calphostin C, as well as by blockade of ATP-sensitive K+ (KATP) channels with blockers of the channel, 10−5 mol/l glibenclamide or 10−4 mol/l 5-hydroxydecanoate. IP also reduced arrhythmia induced by ischemia. Nor-BNI, but not NTD, attenuated, while U50,488H, but not DADLE, mimicked the antiarrhythmic action of IP. In conclusion, the present study has provided first evidence that κ-OR mediates the ameliorating effects of IP on infarct and arrhythmia induced by ischemia, whereas δ-OR mediates the effects only on infarct. Both PKC and KATP channels mediate the effect of activation of κ-OR on infarct.

Role of adenosine in postprandial and reactive hyperemia in canine jejunum

1992 ◽  
Vol 263 (4) ◽  
pp. G487-G493 ◽  
Author(s):  
D. R. Sawmiller ◽  
C. C. Chou
Keyword(s):  
Blood Flow ◽  
Oxygen Consumption ◽  
Adenosine Deaminase ◽  
Reactive Hyperemia ◽  
Concentration Difference ◽  
Adenosine Concentration ◽  
Anesthetized Dogs ◽  
Series Of Experiments ◽  
Increased Blood Flow

The role of adenosine in postprandial jejunal hyperemia was investigated by determining the effect of placement of predigested food into the jejunal lumen on blood flow and oxygen consumption before and during intra-arterial infusion of dipyridamole (1.5 microM arterial concn) or adenosine deaminase (9 U/ml arterial concn) in anesthetized dogs. Neither drug significantly altered resting jejunal blood flow and oxygen consumption. Before dipyridamole or deaminase, food placement increased blood flow by 30-36%, 26-42%, and 21-46%, and oxygen consumption by 13-22%, 21-22%, and 26-29%, during 0- to 3-, 4- to 7-, and 8- to 11-min placement periods, respectively. Adenosine deaminase abolished the entire 11-min hyperemia, whereas dipyridamole significantly enhanced the initial 7-min hyperemia (45-49%). Both drugs abolished the initial 7-min food-induced increase in oxygen consumption. Dipyridamole attenuated (14%), whereas deaminase did not alter (28%), the increased oxygen consumption that occurred at 8-11 min. Adenosine deaminase also prevented the food-induced increase in venoarterial adenosine concentration difference. In separate series of experiments, luminal placement of food significantly increased jejunal lymphatic adenosine concentration and release. Also, reactive hyperemia was accompanied by an increase in venous adenosine concentration and release. This study provides further evidence to support the thesis that adenosine plays a role in postprandial and reactive hyperemia in the canine jejunum.

scholarly journals Roles of gene transcription and PKA subtype activation in maturation of murine oocytes

Reproduction ◽  
2002 ◽  
pp. 799-806 ◽  
Author(s):  
KF Rodriguez ◽  
RM Petters ◽  
AE Crosier ◽  
CE Farin
Keyword(s):  
Gene Transcription ◽  
Cumulus Cell ◽  
Cumulus Cells ◽  
Type I ◽  
Type Ii ◽  
Germinal Vesicle Breakdown ◽  
Series Of Experiments ◽  
And Control ◽  
Alpha Amanitin

The aims of this study were to examine the role of transcription and the coincident involvement of type I and type II protein kinase A (PKA) in the resumption of meiosis in murine cumulus-oocyte complexes (COCs) using the transcriptional inhibitors 5,6-dichloro-1-beta-D-ribofuranosylbenzimidazole (DRB) and alpha-amanitin. The first series of experiments was designed to: (i) characterize the role of transcription in gonadotrophin-mediated and spontaneous maturation of murine oocytes; (ii) examine the roles of specific gonadotrophins (FSH versus hCG) and cumulus cells in transcriptionally mediated oocyte maturation; and (iii) determine the reversibility of the transcriptional arrest of meiosis. In the presence of FSH, transcriptional inhibitors arrested germinal vesicle breakdown (GVBD) (DRB: 2 +/- 2% and control: 76 +/- 2%; alpha-amanitin: 4 +/- 4% and control: 70 +/- 4%). Furthermore, cumulus cells were required for transcriptional inhibitors to arrest GVBD (DRB with cumulus cells: 0 +/- 15%; DRB without cumulus cells: 94 +/- 13%; alpha-amanitin with cumulus cells: 15 +/- 2%; alpha-amanitin without cumulus cells: 99 +/- 2%). Thus, in mice, FSH-mediated GVBD uses a transcriptional mechanism, which probably occurs within the cumulus cell compartment. In a second series of experiments, the role of transcription in mediating the resumption of meiosis after activation of either type I or type II PKA was examined. Activation of type I PKA in murine COCs resulted in an arrest of GVBD that was independent of a transcriptional event (with DRB: 7 +/- 9% GVBD; without DRB: 11 +/- 9% GVBD). In contrast, activation of type II PKA resulted in a resumption of meiosis, which required the occurrence of gene transcription (with DRB: 12 +/- 9% GVBD; without DRB: 80 +/- 9% GVBD). As FSH binding to cumulus cells activates the PKA second messenger system, our results indicate that, in cultured murine COCs, FSH binding to cumulus cells results in the activation of type II PKA, which, in turn, mediates a downstream transcriptional event required for the initiation of GVBD.

scholarly journals Adverse Weather Evokes Nostalgia

2018 ◽  
Vol 44 (7) ◽  
pp. 984-995 ◽  
Author(s):  
Wijnand A. P. van Tilburg ◽  
Constantine Sedikides ◽  
Tim Wildschut
Keyword(s):  
Cognitive Load ◽  
Meteorological Data ◽  
Weather Conditions ◽  
Psychological Benefits ◽  
Adverse Weather

Four studies examined the link between adverse weather and the palliative role of nostalgia. We proposed and tested that (a) adverse weather evokes nostalgia (Hypothesis 1); (b) adverse weather causes distress, which predicts elevated nostalgia (Hypothesis 2); (c) preventing nostalgia exacerbates weather-induced distress (Hypothesis 3); and (d) weather-evoked nostalgia confers psychological benefits (Hypothesis 4). In Study 1, participants listened to recordings of wind, thunder, rain, and neutral sounds. Adverse weather evoked nostalgia. In Study 2, participants kept a 10-day diary recording weather conditions, distress, and nostalgia. We also obtained meteorological data. Adverse weather perceptions were positively correlated with distress, which predicted higher nostalgia. Also, adverse natural weather was associated with corresponding weather perceptions, which predicted elevated nostalgia. (Results were mixed for rain.) In Study 3, preventing nostalgia (via cognitive load) increased weather-evoked distress. In Study 4, weather-evoked nostalgia was positively associated with psychological benefits. The findings pioneer the relevance of nostalgia as source of comfort in adverse weather.

The role of freezing-thaw cycling in rock samples topography evolution and rock cliff retreat

2021 ◽  
Author(s):  
Li Fei ◽  
Marc-Henri Derron ◽  
Tiggi Choanji ◽  
Michel Jaboyedoff ◽  
Chunwei Sun ◽  
...  
Keyword(s):  
Freezing Point ◽  
Meteorological Data ◽  
Test Chamber ◽  
Monitoring Program ◽  
Dynamic Environment ◽  
Rock Properties ◽  
Rock Surface ◽  
Physical Weathering ◽  
Rock Samples

<p>Freezing-thaw weathering is recognized as one of the most significant factors in the fatigue of rock mass in areas where the temperature periodically fluctuates around the freezing point. <br>A one-year monthly SfM monitoring program from December 19, 2019, to January 7, 2021, was done to detect rockfall activity on a rockslide cliff composed of marl-sandstone at La Cornalle, Switzerland. More than one hundred rockfall events were detected during this period with the volumes varied from 0.005m<sup>3</sup> to 4.85m<sup>3</sup>. <br>We texture all the rockfalls on the 3D SfM model. It is shown that most of them are mainly located in three areas:  the top of the cliff, the foot of the cliff, and the medium-left part of the cliff. The common feature of these three parts is that the layers are more or less overhanging with dense fractures around them. At the same time, the meteorological data collected by a weather station on site is correlated with the rockfall events to figure out the relationship between each other. Actually, about 30% of total rockfall volume fell during winter on this site. The triggering factor of rockfall during winter is related to freezing-thaw cycling. This kind of weathering can be understood as an interplay between rock properties and its dynamic environment.<br>In order to make clear the role of freezing-thaw played on the rockfall generation, an on-site 24h monitoring measurement program that consists of two crack meters, one rock thermal sensor, and thermal camera monitoring is installed in January 2021. Those datasets will help to understand how the crack grows with the changing temperature. In addition, freezing-thaw cycling laboratory experiments for the rock samples taken from different areas of the cliff will be done with an environmental test chamber. The topography of the rock samples before and after the experiments will be acquired by a 3D handheld scanner. This work will benefit to reveal the rock surface evolution during the freezing-thaw cycling in a dynamic environment with varied humidity and number of cycles. <br>In conclusion, the combination of on-site measurements and laboratory freezing-thaw experiments will provide a good basis for a better understanding of the rockfall triggering mechanism led by physical weathering.</p>

The role of ultimobranchial bodies in the modulation of the response of chick embryos to 1,25-dihydroxycholecalciferol

Development ◽  
1986 ◽  
Vol 97 (1) ◽  
pp. 87-94
Author(s):  
Roberto Narbaitz ◽  
Jaffar Soleimani Rad
Keyword(s):  
Bone Resorption ◽  
Ethyl Alcohol ◽  
Inorganic Phosphate ◽  
Histological Study ◽  
Chorioallantoic Membrane ◽  
Chick Embryos ◽  
Series Of Experiments ◽  
Ultrastructural Characteristics ◽  
Bone Trabeculae

Ultimobranchial bodies (UBBs) were dissected from 17-day-old chick embryos and grafted onto the chorioallantoic membrane of 8-day-old embryos. The embryos with UBB grafts as well as sham-grafted controls were injected on the 10th day of incubation with 100 ng 1,25(OH)2D3 dissolved in ethyl alcohol or with an equal volume of ethyl alcohol alone; embryos were sacrificed on the 13th day. Grafted UBBs showed ultrastructural characteristics typical of actively secreting glands. A histological study of the tibiae from all embryos showed that while the grafted embryos responded to the injection of 1,25(OH)2D3 with a peripheral rim of undermineralized bone trabeculae, sham-grafted embryos never did so. These results confirm the original hypothesis that the presence of differentiated UBBs is a precondition for the production of undermineralized bone (osteoid) by 1,25(OH)2D3. In a second series of experiments, similarly treated embryos were sacrificed on the 10th, 11th, 12th and 13th day; the levels of calcium and inorganic phosphate were determined in their blood. The injection of 1,25(OH)2D3 produced in all embryos hypercalcaemia and hypophosphataemia. However, the hypophosphataemic response was more prolonged in the embryos with UBB grafts than in sham-grafted ones. These results suggest that the grafted UBBs prolonged the hypophosphataemic response, probably by secreting calcitonin and thus reducing the rate of bone resorption. It is also probable that the prolonged hypophosphataemia produced or contributed to the undermineralization of the peripheral (subperiosteal) trabeculae.

The Caribbean, Carlos Finlay, Walter Reed, and Serendipity

2021 ◽  
pp. 182-197
Author(s):  
Robert N. Wiedenmann ◽  
J. Ray Fisher
Keyword(s):  
Puerto Rico ◽  
Aedes Aegypti ◽  
Yellow Fever ◽  
Spanish American ◽  
Spanish American War ◽  
Spanish Colonies ◽  
Series Of Experiments ◽  
The Caribbean ◽  
Post War

This chapter reviews the role of expanding sugarcane plantations throughout the Caribbean in the movement of slaves, mosquitoes and disease, as world empires jockeyed for dominance in world sugar markets. It relates how increased sugarcane production and exports to Europe led to increased importation of slaves to work the fields. As the African embarkation point of slaves moved north to the Slave Coast, yellow fever and the mosquito Aedes aegypti came into play, though when England banned slaveholding, sugar production shifted to the Spanish colonies of Puerto Rico and Cuba. The brief Spanish-American War of 1898, over control of Cuba, cemented the fame of Colonel Theodore Roosevelt but resulted in more deaths from yellow fever than combat, with the outbreak continuing during the post-war occupation of Cuba. Serendipity played a significant role in the subsequent discovery of the cause of the disease, connecting the Yellow Fever Commission, led by Major Walter Reed, with Cuban physician, Dr. Carlos Finlay, whose early experiments pointed to mosquitos and others while a series of experiments by Reed's team showed Aedes aegypti was the vector.

Sign in / Sign up

Export Citation Format

Share Document