bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Wake Dynamics and Flight Forces of the Fruit Fly Drosophila Melanogaster
Authors: Dickinson Michael H. , Götz Karl G. 
Published: April 2021

ABSTRACT
We have used flow visualizations and instantaneous force measurements of tethered fruit flies (Drosophila melanogaster) to study the dynamics of force generation during flight. During each complete stroke cycle, the flies generate one single vortex loop consisting of vorticity shed during the downstroke and ventral flip. This gross pattern of wake structure in Drosophila is similar to those described for hovering birds and some other insects. The wake structure differed from those previously described, however, in that the vortex filaments shed during ventral stroke reversal did not fuse to complete a circular ring, but rather attached temporarily to the body to complete an inverted heart-shaped vortex loop. The attached ventral filaments of the loop subsequently slide along the length of the body and eventually fuse at the tip of the abdomen. We found no evidence for the shedding of wing-tip vorticity during the upstroke, and argue that this is due to an extreme form of the Wagner effect acting at that time.
The flow visualizations predicted that maximum flight forces would be generated during the downstroke and ventral reversal, with little or no force generated during the upstroke. The instantaneous force measurements using laser-interferometry verified the periodic nature of force generation. Within each stroke cycle, there was one plateau of high force generation followed by a period of low force, which roughly correlated with the upstroke and downstroke periods. However, the fluctuations in force lagged behind their expected occurrence within the wing-stroke cycle by approximately 1 ms or one-fifth of the complete stroke cycle. This temporal discrepancy exceeds the range of expected inaccuracies and artifacts in the measurements, and we tentatively discuss the potential retarding effects within the underlying fluid mechanics.
3-Hydroxybutyrate Co-Infused With Noradrenaline Decreases Resulting Plasma Levels Of Noradrenaline In Wistar Rats
Authors: Cañas X. , Sanchis D. , Gómez G. , Casanovas J. M. , Artigas F. , Fernández-lópez J. A. , Remesar X. , Alemany M. 
Published: April 2021

ABSTRACT
Pentobarbital-anaesthetized male Wistar rats were infused with 6 μg kg−1 min−1 of noradrenaline. The infusion was supplemented with 8.5 mg kg−1 min−1 of D-3-hydroxybutyrate (3-OHB) for 15 min in order to determine its effect on the adrenergic response of the rat. Plasma levels of noradrenaline rose to a plateau of approximately 50 nmol l−1 with infusion. In the group infused with noradrenaline alone, noradrenaline levels were maintained for 1 h. Supplementation with 3-OHB induced a decrease in plasma noradrenaline level that was inversely correlated with 3-OHB level. Aortic and interscapular brown adipose tissue temperatures increased with noradrenaline infusion, but the rise was arrested by 3-OHB; replacing 3-OHB with glucose had no effect. Infusion of saline, glucose or 3-OHB in the absence of noradrenaline did not induce a rise in temperature in either tissue. Blood 3-OHB concentration increased to 1.2 mmol l−1 during 3-OHB infusion, decreasing rapidly at the end of infusion. Blood glucose levels increased with noradrenaline infusion; the presence of high 3-OHB levels decreased glucose concentration. The effects observed were transient and dependent on 3-OHB concentration; these effects may help explain most of the other effects of noradrenaline described here. The role of 3-OHB as a regulator of adrenergic responses seems to be part of a complex fail-safe mechanism which prevents wasting.
Hyperosmoregulation in the red freshwater crab Dilocarcinus pagei (Brachyura, Trichodactylidae): structural and functional asymmetries of the posterior gills
Authors: Onken Horst , McNamara John Campbell 
Published: April 2021

SUMMARY
The osmotic and ionic status of the haemolymph and the structural and ion-transport characteristics of the posterior gills of Dilocarcinus pagei, a hololimnetic crab, were investigated. Haemolymph osmolality was 386±18 mosmol kg–1, while [Na+] and [Cl–] were 190±13 and 206±12 mmol l–1, respectively; [K+], [Ca2+] and [Mg2+] were 9.7±0.7, 10.2±0.5 and 2.8±0.4 mmol l–1, respectively (means ± s.e.m., N=12–17). The gill lamellae possess a central, osmiophilic area, which exhibits a marked structural asymmetry. The thick (18–20 μm) proximal epithelium is characterised by basal invaginations and a few apical vesicles, while the thin (3–10 μm) distal epithelium consists of apical pillar cell flanges populated by vesicles and membrane invaginations. Isolated gills, bathed and perfused with NaCl saline, spontaneously generate a negative transbranchial potential difference (Vte), which stabilises at positive or negative values. Ouabain shifts Vte to more positive values. When mounted in an Ussing chamber, distal split lamellae generate a negative, Cl–-dependent short-circuit current (Isc). Na+ substitution leads to more negative values of Isc. Internal ouabain is without effect, while diphenylamine-2-carboxylate and acetazolamide abolish Isc. Proximal split lamellae show a positive, Na+-dependent Isc, which decreases after internal application of ouabain. These data suggest that the thin epithelium actively absorbs Cl–, while the thick epithelium actively absorbs Na+.
The under-appreciated fats of life: the two types of polyunsaturated fats
Authors: Hulbert A. J. 
Published: April 2021

ABSTRACTThere are two types of polyunsaturated fatty acids (i.e. fats that contain multiple carbon-carbon double bonds) – omega-6 and omega-3. They are not interconvertible, and they contribute ‘double-bonded carbons’ to different depths in bilayer membranes, with different effects on membrane processes. This Commentary emphasises the importance of these fats for biological membrane function and examines their evolution and biochemistry. Omega-6 and omega-3 fatty acids are separately essential in the diet of animals, and they pass up the food chain largely from plants, with ‘seeds’ being a prevalent source of omega-6, and ‘leaves’ a prevalent source of omega-3. The dietary balance between these fatty acids has a strong influence on membrane composition. Although this aspect of diet has been little investigated outside of the biomedical field, emerging evidence shows it can alter important physiological capacities of animals (e.g. exercise endurance and adiposity), which has implications for activities such as avian migration and hibernation and torpor, as well as significant implications for human health. This Commentary will focus on the separate effects of omega-3 and omega-6 on membrane properties and will emphasise the importance of the balance between these two fatty acids in determining the function of biological membranes; I hope to convince the reader that fats should be considered first and foremost as the basic unit of biological membranes, and secondarily as a means of energy storage.
The Spectral Sensitivity of the Echinoid Diadema Antillarum Philippi
Authors: Millott N. , Yoshida M. 
Published: April 2021

ABSTRACT
Several species of sea urchin show sensitivity to light, by the reactions of the whole animal or those of effectors such as the spines, podia, pedicellariae and chromatophores. The reactions have recently been reviewed by Millott (1954, 1956, 1957a).
Co-Ordinating Systems and Behaviour in Hydra
Authors: Passano L. M. , McCullough C. B. 
Published: April 2021

ABSTRACT
In the first paper of this series (Passano & McCullough, 1964) we described the system concerned with the periodic bursts of impulses arising from the subhypostome and conducted throughout the column of several species of the genus Hydra, the familiar freshwater polyp (hydrozoan coelenterate). Each of these bursts of impulses is followed by a co-ordinated contraction of the epidermal, longitudinally arranged muscles, so that the total burst of this contraction-burst system results, in reducing the animal to a stubby ball. Periodic contraction bursts (CB) are the most important overt behaviour of Hydra.
The Relation Between Age and Flight Activity in the Milkweed Bug, Oncopeltus
Authors: Dingle Hugh 
Published: April 2021

ABSTRACT
The mean flight-duration, in tethered flight, of the ‘large milkweed bug’, Oncopeltus fasciatus (Dallas), was measured as a function of age in days after the final moult. In both sexes a peak of flight occurs at 8-10 days. In males there is a second flight peak at 30-35 days, whereas there is no second peak in females. Virgin males tested at 20 days, a time when mated males were short-flying, flew longer than bugs at any other age. Thirty-day-old virgin females were not significantly different from mated females of the same age. When long flights occurred in males they were in general preceded by one or more flights of less than 1 min. This was not true for females, and the difference between the sexes was statistically significant. The results in 2, 3 and 4, above indicate two, and possibly three, differences between the sexes. Males and females should thus be studied separately with respect to flight activity. Some individuals never flew. These were as long-lived and as "productively active as those which did, indicating the possibility of a behavioural polymorphism. The initial peak of mean flight-duration for both sexes occurs when the daily deposition of paired cuticular growth rings ceases. Maximum flight thus seems to occur at the end of the teneral period. The threshold for flight declines with age. There are thus three types of flight : long-duration, high-threshold; short-duration, low-threshold; and (in males only) long-duration, low-threshold. The initial flight peak is pre-reproductive and occurs at a time when reproductive value, a measure of the expected contribution of an individual to future population growth and hence of sensitivity to selection, is high. Long-flying bugs are evidently colonizers, and a migration is an evolved adaptation, not a response to current adversity. It is concluded that the long-duration, high-threshold flights represent migration and the short-duration, low-threshold flights represent non-migratory ‘flits’.
Proprioception by the Coxo-Basal Chordotonal Organ, Cb, in Legs of the Crab, Carcinus Maenas
Authors: Bush B. M. H. 
Published: April 2021

ABSTRACT
The chordotonal organ, CB, spanning the coxo-basal joint in walking legs of the crab, not being attached to a muscle tendon like the receptors of the more distal joints, is stretched during extension of the joint (i.e. limb depression) and relaxes during flexion (elevation). Afferent impulses have been recorded extracellularly from whole sensory nerves of CB, and from fibres isolated from it: (a) during passive movement of the coxo-basal joint, with CB in situ in a preparation containing no other joints, and (b) during stretching and releasing of the excised receptor strand. Unidirectional movement fibres and unidirectional position fibres for both directions were recorded. Thus, of the afferents responding primarily during movement, with a constant frequency for steady movement over the whole joint arc, some responded only during extension (or stretch of receptor), others only during flexion (release). Similarly, distinct fibres responded tonically in the extended positions of the joint (stretched), and others in the flexed (relaxed) positions. Fibres intermediate between true movement and true position fibres, and phasic movement—or ‘acceleration’— fibres, were also observed. Since the scolopidia of CB are isodynal, with only ciliary-type distal processes (Whitear, 1962), the simple hypothesis that the ciliary cell responds solely to relaxation of the receptor strand—and the paraciliary cell to stretch—is now untenable. Alternative hypotheses on the mechanism of activation of crab chordotonal organs, and on the function of CB in the intact animal, are discussed.
Structural Limitations on the Power Output of the Pigeon’s Flight Muscles
Authors: Pennycuick C. J. , Parker G. A. 
Published: April 2021

ABSTRACT
The tensile strength of the flight-muscle tendons, the distances through which they move and the wingbeat frequency set a maximum of 48 W on the power which could conceivably be transmitted to the pigeon’s wings. A minimum of 0·1 W is required to account for observed climbing performance. The safety factor on tension of the muscle insertions cannot exceed 5·2 and is probably substantially less than this. The maximum possible average specific power over one complete cycle is 0·58 W/g.wt. for the pectoralis and 0·28 W/g.wt. for the supracoracoideus. The maximum possible peak specific power during shortening is 0·86 W/g.wt. for both muscles. The minimum average specific power for the flight muscles as a whole is 0·10 W/g.wt. (from rate of climb measurements). These figures do not imply any unusual mechanical properties in the muscles, as compared to other vertebrate muscles. The coracoid can bear a compressive load of over 40 kg. wt., which appears to be about 3·7 times as much as could ever be applied to it in life. The greatest bending moment (about the centre of rotation of the head of the humerus) which the pectoralis could apply to the humerus is 10·2 kg. wt. cm. The supracoracoideus could apply a maximum of 0·88 kg. wt. cm. The tensile strength of supracoracoideus tendon is about 250 kg. wt./cm.2. The compressive strength of coracoid bone is about 1140 kg. wt./cm.2.
Reflexes Mediated by Non-Impulsive Afferent Neurones of Thoracic-Coxal Muscle Receptor Organs in the Crab, Carcinus Maenas
Authors: Cannone A. J. , Bush B. M. H. 
Published: April 2021

ABSTRACT
Injection of depolarizing and hyperpolarizing currents into the non-impulsive S and T sensory fibres has allowed a quantitative analysis of the input-output relationships of this sensory-reflex system. Graded depolarization of the T fibre typically results in sigmoid voltagefrequency relationships for motoneurones Pm 1–3, the maximum ‘slopes’ in the most sensitive preparation being 31, 47·5 and 33 Hz/mV respectively, without taking into account further afferent attenuation within the thoracic ganglion. Graded depolarizations of the S fibre recruit four motoneurones (Pm 1–4) common to the T fibre reflex pathway, although activation thresholds are much higher and the maximum slope or ‘gain’ of the voltagefrequency relationships is much reduced compared to that of the T fibre reflex pathways. Thus, although the S fibre synapses either directly or indirectly with promotor motoneurones, typical 5–10 mV stretch-induced receptor potentials remain sub-threshold for a contribution to the reflex output, albeit under experimental conditions and at all but the most extended receptor muscle lengths. Differentiating between motor impulse amplitudes, and using simultaneously recorded promotor muscle junction potentials as a further aid, establishes at least nine motoneurones as being reflexly recruited by the S and T fibres: Pm 1–8 by the T fibre and Pm 1–4 and Pmq by the S fibre. Hyperpolarization of the T and S fibres confirms that ongoing tonic motor activity is peripherally determined by receptor length proscribed T fibre ‘resting’ potentials, rather than by the more linearly related S fibre ‘resting’ potentials at different receptor muscle lengths. Moreover, suppression of the reflex response by sensory fibre hyperpolarizations coincident with stretch stimuli leaves little doubt that it is the T rather than the S fibre that provides the sensory drive for the stretch reflex in vitro. By using long duration, constant value T fibre depolarizing potentials, the postsynaptic component of adaptation for Pm 1–3 has been found to be slight, in contrast to the more rapid adaptation of the higher threshold P1T15–8 motoneurones. Moreover, adaptation rates for Pm 1–3 discharges are lower the smaller the afferent drive. It is suggested therefore that reflexly activated promotor MNs can be differentiated into ‘tonic’ and ‘phasic’ categories. Motoneurone Pm2 sometimes discharges in the form of ‘rigid’ (7–8 ms intervals) impulse couplets. At low mean reflex frequencies all Pm2 impulses are locked into couplets (‘complete’ patterning). While both ‘rigid’ and ‘complete’ patterning break down abruptly as mean frequencies increase, re-establishment is more gradual (hysteretic) with decreasing mean frequencies. Patterning, albeit a particularly labile phenomenon, is almost certainly an intrinsic, if unknown, property of the motoneurone itself.
Movement Parallax and Distance Perception in the Grasshopper (Phaulacridium Vittatum (Sjöstedt))
Authors: Eriksson E. S. 
Published: April 2021

ABSTRACT
It has sometimes been argued that insects use binocular vision to obtain correct perception of sizes and distances in their visual world (cf. Wigglesworth, 1972). In the praying mantids it has also been claimed that monocular animals essentially lack depth perception (Maldonado, Benko & Isern, 1970).
Energetic Cost of Generating Muscular Force During Running
Authors: Taylor C. Richard , Heglund Norman C. , McMahon Thomas A. , Looney Todd R. 
Published: April 2021

ABSTRACT
The energetic cost of generating muscular force was studied by measuring the energetic cost of carrying loads in rats, dogs, humans, and horses for loads ranging between 7 and 27 % of body mass.
Oxygen consumption increased in direct proportion to mass supported by the muscles, i.e. where is the oxygen consumption of the animal running with a load, is the oxygen consumption at the same speed without a load, mL is the mass of the animal plus the load, and m is the mass of the animal.
Stride frequency, average number of feet on the ground over an integral number of strides, the time of contact of each foot relative to the other feet, and the average vertical acceleration during the contact phase were not measurably changed by the loads used in our experiments. From these observations we conclude that the average accelerations of the centre of mass of the animal are not changed by carrying the loads, and that muscular force developed by the animal increases in direct proportion to the load.
It follows that the rate of energy utilization by muscles of an animal as it runs along the ground at any particular speed is nearly directly proportional to the force exerted by its muscles.
The energetic cost of generating force over an interval of time (∫Fdt) increases markedly with running speed.
An important consequence of the direct proportionality between increased oxygen consumption and mass of the load is that small animals expend much more energy to generate a given force at a given speed than large animals.
High-resolution fast mid-wave infrared compressive imaging
Authors: Zhang Linxia , Ke Jun , Chi Sheng , Hao Xiaowen , Yang Tong , Cheng Dewen 
Published: April 2021

In the mid-wave infrared (MIR) band, large detector arrays are extremely costly and technically difficult to be manufactured. Thus, it is difficult to obtain high-resolution images for a conventional MIR camera. Spatial compressive imaging can improve resolution. However, system errors due to misalignment or optical aberrations degrade reconstruction quality significantly. Another common issue for compressive imaging is the slow imaging speed, which is caused by slow measurement collection and reconstruction processes. To deal with the two issues, we use an imaging calibration method to improve reconstruction quality and a sliding window measurement collection strategy plus a reconstruction algorithm accelerated by parallel computing to fasten the speed. We build a prototype of a compressive imaging camera with an angular resolution 1.17 lp/mrad. A four-bar target is used as an object. We reconstruct a moving scene of size

1280
×
1024

with a frame rate 20 frames per second.
Metagenomic sequencing reveals viral abundance and diversity in mosquitoes from the Shaanxi-Gansu-Ningxia region, China
Authors: He Xiaozhou , Yin Qikai , Zhou Liwei , Meng Lei , Hu Weijun , Li Fan , Li Yang , Han Kun , Zhang Shaobai , Fu Shihong , Zhang Xiaoshu , Wang Ji , Xu Songtao , Zhang Yi , He Ying , Dong Maoxing , Shen Xinxin , Zhang Zheng , Nie Kai , Liang Guodong , Ma Xuejun , Wang Huanyu 
Published: April 2021

Background
Mosquitoes host and transmit numerous arthropod-borne viruses (arboviruses) that cause disease in both humans and animals. Effective surveillance of virome profiles in mosquitoes is vital to the prevention and control of mosquito-borne diseases in northwestern China, where epidemics occur frequently.

Methods
Mosquitoes were collected in the Shaanxi-Gansu-Ningxia region (Shaanxi Province, Gansu Province, and Ningxia Hui Autonomous Region) of China from June to August 2019. Morphological methods were used for taxonomic identification of mosquito species. High-throughput sequencing and metagenomic analysis were used to characterize mosquito viromes.

Results
A total of 22,959 mosquitoes were collected, including Culex pipiens (45.7%), Culex tritaeniorhynchus (40.6%), Anopheles sinensis (8.4%), Aedes (5.2%), and Armigeres subalbatus (0.1%). In total, 3,014,183 (0.95% of clean reads) viral sequences were identified and assigned to 116 viral species (including pathogens such as Japanese encephalitis virus and Getah virus) in 31 viral families, including Flaviviridae, Togaviridae, Phasmaviridae, Phenuiviridae, and some unclassified viruses. Mosquitoes collected in July (86 species in 26 families) showed greater viral diversity than those from June and August. Culex pipiens (69 species in 25 families) and Culex tritaeniorhynchus (73 species in 24 families) carried more viral species than Anopheles sinensis (50 species in 19 families) or Aedes (38 species in 20 families) mosquitoes.

Conclusion
Viral diversity and abundance were affected by mosquito species and collection time. The present study elucidates the virome compositions of various mosquito species in northwestern China, improving the understanding of virus transmission dynamics for comparison with those of disease outbreaks.