bluuebunny/crossref_metadata_2025_split huggingface dataset:
Reactions of Salmonid Larvae to Light
Authors: Woodhead P. M. J. 
Published: April 2021

ABSTRACT
The larvae of the brown trout, rainbow trout, and salmon were periodically active and negatively phototactic when illuminated. All three species exhibited a positive photo-orthokinesis, the duration of their activity being directly proportional to the log of the light intensity, over a limited range. The light threshold for the kinesis was about 0.005 m.c. but tended to be higher in many young larvae and lower in larvae of a later stage. An upper limit, although more variable, was demonstrated in some individuals, and lay between about 10 and 100 mc. in the older larvae. It is suggested that a photo-orthokinesis, coupled with a negative phototaxis, berves well to maintain the larvae within the limits of their normal habitat at this stage of development. No adaptation of the kinesis occurred after periods of up to 90 min. illumination. But larvae did exhibit a rhythm of activity, reaching peaks at intervals of about 15 min. An increase in the general level of activity, at all light intensities, occurred as the larvae grew, until they were M y active throughout an observation period. At this point the behaviour of the young fish changed, in particular the negative phototaxis was lost and the fish soon began to feed. The increase in the level of activity may be regarded as an index of development in trout and was shown to be related to the general growth of the embryo. Rainbow trout ova hatch about a week earlier than brown trout at l0° C. This does not necessarily indicate a more rapid development in the rainbow trout, Since the latter takes a week longer to achieve full activity, both species reaching this stage at about sixty days after fertilization. The behaviour of the salmon larva does not seem to be strictly comparable with that of the trout during the later sbges of developement
The Effect of A Biological Clock on the Developmental Rate of Drosophila Pupae
Authors: Harker Janet E. 
Published: April 2021

ABSTRACT
A study of the course of pupal development in two strains of Drosophila melanogaster has been made in an attempt to establish the factors affecting the time of adult eclosion. The time taken to complete three stages of pupal development has been measured for pupae entering each stage at each particular hour of the day when insects were kept in 12 hr. light: 12 hr. darkness, 12 hr. bright light: 12 hr. dim light, or in continuous darkness. The duration of each stage, in both strains, is affected by the time of day, relative to the light cycle, at which the stage is entered. The duration of each stage for pupae kept in continuous darkness is affected by the time of day at which the stage is entered, relative to the light cycle to which they had been exposed as larvae. The time-interval curves for all three stages of any one strain take the same form. Because of the very wide range of developmental rates, dependent upon the time within the light cycle at which each stage begins, a population in which the larvae all pupate within a 24 hr. period will continue to produce adult flies over several days. The eclosion rhythm is a population effect and does not reflect the phasing of individuals to a dawn eclosion; the majority of adults emerge at dawn because of the summation effect of circadian rhythms of development at earlier stages.
A Multilayer Interference Reflector in the Eye of the Scallop, Pecten Maximus
Authors: Land M. F. 
Published: April 2021

ABSTRACT
Animals frequently make use of highly reflecting surfaces, as for example in the tapeta of the eyes of many vertebrates, the iridophores and photophores of many marine animals, and the scales of fish. Such surfaces raise the question: how are high reflectivities, often comparable with that of polished metal, achieved using biological materials?
The Site of Release of the Diuretic Hormone in Rhodnius—A New Neurohaemal System in Insects
Authors: Maddrell S. H. P. 
Published: April 2021

ABSTRACT
This investigation has sought the site of release of the diuretic hormone which appears in the haemolymph of larvae of Rhodnius shortly after they begin feeding. Material possessing diuretic activity can be extracted in high concentration from those lengths of the peripheral abdominal nerves which lie just behind the mesothoracic ganglionic mass. An electron microscope study of the mesothoracic ganglionic mass and the abdominal nerves which leave it has shown that the axons from the neurosecretory cell bodies in the ganglionic mass some of which at least have previously been shown to contain the diuretic hormone run out into the proximal lengths of the abdominal nerves where they branch. Some of the branches have been followed to neurosecretory axon endings which typically are packed with neurosecretory granules and lie immediately beneath the fibrous nerve sheath. By constricting fed insects at various positions it has been possible to show that most of the diuretic hormone is released into the region close to but behind the mesothoracic ganglionic mass. It is concluded that the release of diuretic hormone in Rhodnius is from a series of swollen neurosecretory axon endings dotted over the surface of those lengths of the peripheral abdominal nerves which lie close to the mesothoracic ganglionic mass.
Excretory role of the midgut in larvae of the tobacco horn worm, Manduca sexta (L.)*
Authors: Nijhout H.F. 
Published: April 2021

ABSTRACT
Caterpillars of Manduca sexta use two distinct transport mechanisms for the excretion of dyes. One pump (Type A) has a high affinity for acid (anionic) dyes and occurs in the midgut and medial Malpighian tubules. Acid dyes accumulate rapidly in the lumen of the midgut while the Malpighian tubules appear to play only a minor role in the excretion of these dyes. The other pump (Type B) excretes basic (cationic) dyes and is located primarily in the proximal Malpighian tubules. Evidence is presented that hippuric acid competes with acid dyes for excretion by both midgut and Malpighian tubules. After the final-instar larva purges its gut the ability of the midgut and Malpighian tubules to excrete dyes gradually decreases. Sixty hours after the purge only the Malpighian tubules retain some dye excreting activity.
Applicability of hydrodynamic analyses of spermatozoan motion
Authors: Yundt A.P. , Shack W.J. , Lardner T.J. 
Published: April 2021

ABSTRACT
This paper investigates the applicability of a simple hydrodynamics theory due to Gray & Hancock (1955), and extended by Brokaw (1970), to the analysis of the motions of sea urchin, rabbit, and bull spermatozoa. Experimental procedures for filming and analysing the swimming motions are presented. A detailed discussion of the agreement between the experimental and theoretical results is given, and the limitations of the theory in analysing the motion of mammalian spermatozoa are discussed.
The mechanism of plasticization of the abdominal cuticle in Rhodnius
Authors: Reynolds S.E. 
Published: April 2021

ABSTRACT
The mechanism of plasticization of the abdominal cuticle in Rhodnius larvae has been investigated, using the properties of loops of cuticle under varying test conditions as a model for the behaviour of the cuticle in vivo. It is supposed that plasticization is effected by a change in the intracuticular environment. A number of model mechanisms for plasticization may be proposed, which suppose that the epidermis is capable of regulating (a) pH, (b) ionic strength, (c) Ca and/or Mg, (d) urea, within the cuticle. Analyses of cuticle ash show that models (b) and (c) are not responsible for plasticization in vivo. The levels of inorganic ions within the unplasticized cuticle are not sufficiently high to allow plasticization upon their removal. No evidence for model (d) has been found; urea does not occur in the cuticle in detectable quantities. Exact measurements of the intracuticular pH have not been achieved but staining experiments strongly suggest that a change in pH occurs within the cuticle on plasticization. This pH change is probably large enough to account for the increased extensibility shown by plasticized cuticle.
Proprioceptive motor control in fish respiration
Authors: Ballintijn C.M. , Bamford O.S. 
Published: April 2021

ABSTRACT
The response of single respiratory neurones in the medulla oblongata of carp to short twitches of individual respiratory muscles were analysed. The muscle contractions were obtained through automatic electrical stimulation and could be consistently elicited in a predetermined phase relation to the ventilatory cycle. The results show that, apart from nerve cells which take part in long-term processing of proprioceptive information from several sources, neurones also exist which possess the properties of elements of a peripheral proprioceptive control loop such as tension receptor neurones, length or stretch receptor neurones and motor neurones.
Directional Hearing in the Japanese Quail (Coturnix Coturnix Japonica)
Authors: Coles R. B. , Lewis D. B. , Hill K. G. , Hutchings M. E. , Gower D. M. 
Published: April 2021

ABSTRACT
The directional sensitivity of cochlear microphonics (CM) was studied in the quail by rotating a free-field sound source (pure tones, 160–10 kHz) through 360° in the horizontal plane, under anechoic conditions. Sound diffraction by the head was monitored simultaneously by a microphone at the entrance to the ipsilateral (recorded) ear canal. Pressure-field fluctuations measured by the microphone were non-directional (⩽ 4 dB) up to 4 kHz ; the maximum head shadow was 8 dB at 6·3 kHz. In comparison, the CM sensitivity underwent directional fluctuations ranging up to 25 dB for certain low, mid and high frequency bandwidths. There was noticeable variation between quail for frequencies producing maximum directional effects, although consistently poor directionality was seen near 820 Hz and to a lesser extent near 3·5 kHz. Well-defined CM directivity patterns reflected the presence of nulls (insensitive regions) at critical positions around the head and the number of nulls increased with frequency. Five major types of directivity patterns were defined using polar co-ordinates: cardioid, supercardioid, figure-of-eight, tripartite and multilobed. Such patterns were largely unrelated to head shadow effects. Blocking the ear canal contralateral to the recorded ear was shown to effectively abolish CM directionality, largely by eliminating regions of insensitivity to sound.
It is inferred that the quail ear functions as an asymmetrical pressure gradient receiver, the pressure gradient function being mediated by the interaural cavity. It is proposed that the central auditory system codes directional information by a null detecting method and computes an unambiguous (i.e. intensity independent) directional cue. This spatial cue is achieved by the difference between the directional sensitivities of the two ears, defined as the Directional Index (DI). The spatial distribution of DI values (difference pattern) demonstrated ranges and peaks which closely reflected the extent and position of nulls determined from monaural directivity functions. Large directional cues (up to 25 dB) extended throughout most of the audible spectrum of the quail and the sharpness of difference patterns increased with frequency. Primary ‘best’ directions, estimated from peaks in difference patterns, tended to move towards the front of the head at higher frequencies; rearward secondary peaks also occurred. From the properties of directional cues it is suggested that the ability of birds to localize sound need not necessarily depend on frequency; however, spatial acuity may be both frequency and direction dependent, and include the possibility of front-to-rear errors. The directional properties of bird vocalizations may need to be reassessed on the basis of the proposed mechanism for directional hearing.
Studies on Locust Rectum
Authors: Spring J. H. , Phillips J. E. 
Published: April 2021

ABSTRACT
Homogenates of whole corpora cardiaca (CC) cause increases in the short-circuit current (Isc) and transepithelial electropotential difference (PD) across locust recta of 3-fold and 1·7-fold respectively, in comparison with the values for unstimulated steady-state recta. Maximum stimulation restores rectal Isc and PD to levels observed immediately after removing this organ from animals. Cyclic-AMP causes a similar maximum increase in Isc and PD; however, the response exhibits a much shorter lag time and a faster rate of rise than is observed for stimulation with CC. The addition of CC to the haemocoel side of everted rectal sacs caused whole tissue levels of cAMP in this organ to increase 3-fold. The relationship between the logarithm of CC or cAMP concentration and the increase in Iscis linear, and the decline in ΔIsc with time is also dose dependent. Small maximum increases in Isc are caused by homogenates of ventral ganglia, whole brain and rectal tissue, but the concentration of the stimulatory activity in these locust tissues is clearly three orders of magnitude lower than in CC. Inhibitors of HCO3−/H+ and Cl− transport in vertebrate systems, acetazolamide and thiocyanate, do not inhibit the stimulation of recta by CC or cAMP.
Short Communications Piezoelectric Drive for Step-By-Step Microelectrode Advancement
Authors: Peters Malte , Tetzel Hans D. 
Published: April 2021

ABSTRACT
It is a common experience in working with glass-microelectrodes that penetration of a cell is performed with greatest ease if a single thrust of high velocity is applied to either the electrode or the preparation. In most cases this is accomplished by tapping on the base of the experimental set-up, or on the micromanipulator carrying the electrode. However, it is often difficult to impale small cells with this method. Various attempts have been made to overcome this difficulty by the use of electromechanical drives of high speed and spatial resolution. These include electromagnetic (Fish et al. 1971; Tomita, 1969), stepping motor (Brown & Flaming, 1977) and piezoelectric devices. Potentially, piezoelectric transducers are most suitable for these applications because of their high speed. Single elements, however, are hampered by the fact that only small excursions can be obtained at high voltages. To obtain a larger working range it is necessary to use either devices composed of many elements stacked in series or piezoelectric bender elements. There are several reports on microelectrode drives incorporating bender-elements (Lassen & Sten-Knudsen, 1968; Prazma, 1978; Tupper & Rikmenspoel, 1969) but the mechanical response to an applied electrical signal has not been documented.
Alloxazinium-Resins as Readily Available and Reusable Oxidation Catalysts
Authors: Arakawa Yukihiro , Kawahara Takayuki , Minagawa Keiji , Imada Yasushi 
Published: April 2021

Abstract
N5-Modified alloxazinium salts including 5-ethyl-1,3-dimethylalloxazinium and 5-ethyl-1,3-dimethyl-8-(trifluoromethyl)alloxazinium salts were readily prepared as alloxazinium-resins from the corresponding N5-unmodified ingredients via the aerobic oxidation—ion exchange protocol, previously introduced by us for the preparation of isoalloxazine analogues, and their catalysis and reusability in H2O2 oxidations were evaluated.
The association between monocyte HDL ratio and albuminuria in diabetic nephropathy
Authors: Efe Fatma Kaplan 
Published: April 2021

Objectives: We aimed to investigate whether Monocyte-to-HDL ratio (MHR) had an association with albuminuria in patients with diabetic nephropathy (DN).
Methods: Diabetic patients, who had admitted to the outpatient clinic of general internal disease department between September 2017 - February 2018 and had their spot urinary albumin/creatinine ratio measured, were examined retrospectively. Patients were separated based on the presence of DN. Patients with DN were grouped as Stage-I, Stage-II and Stage-III chronic kidney disease (CKD). Groups were compared in terms of MHR. The presence of a correlation between MHR and albuminuria was investigated.
Results: MHR was found to be higher in the DN (n=85) group compared to Non- DN group. (16.2±5.5 vs. 14.3±4, p=0.037) And there was no significant difference in Stage-I, Stage-II and Stage-III CKD groups in terms of MHR. (15.2± 3.4, 16.1±6.0, 17.1±6.0, p=0.485). No significant correlation was found between MHR and albuminuria in DN and non-DN groups (p=0.634, r=0.052; p=0.553, r=-0.059).
Conclusions: DN group had higher MHR than non-nephropathy group, whereas, there was no correlation between albuminuria and MHR.
doi: https://doi.org/10.12669/pjms.37.4.3882
How to cite this:Efe FK. The association between monocyte HDL ratio and albuminuria in diabetic nephropathy. Pak J Med Sci. 2021;37(4):1128-1132. doi: https://doi.org/10.12669/pjms.37.4.3882
This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Online assessment in undergraduate medical education: Challenges and solutions from a LMIC university
Authors: Fatima Syeda Sadia , Idress Romana , Jabeed Kausar , Sabzwari Saniya , Khan Sadaf 
Published: April 2021

Background and Objectives: The Covid-19 pandemic has caused large-scale disruption in almost all educational programs across the world. Planning and rapid implementation of assessment through an online format presents the next set of novel challenges that must be addressed by academic administrations across the globe.
Methods: This cross-sectional study was conducted between March to August 2020 at the Aga Khan University Medical College. Two hundred medical students of year 1 and 2 participated in the study. We describe the planning, processes, and outcomes of online assessments using video communication platforms conducted at a private university in Pakistan. Standardized protocols were written and piloted, extensive training of student, proctors and staff for preparation and conduct of online assessments were developed. Feedback was recorded after each session and suggestions were incorporated in subsequent high-stakes assessments.
Results: A total of three pilot assessments were conducted to identify issues and process refinement. Commercially available lockdown browser and ZOOM were used in the first pilot; 80% of the class was unable to launch lockdown browser and laptops required repeated reload/reboot. For the second pilot assessment, University’s VLE page & MS Teams was trailed. Issues with internet connectivity, VLE page slowdown, and suboptimal recording feature in MS Teams were identified. For the final pilot assessment, phased launching of VLE page with single test item per page was implemented with success. The students reported that attempting the online exam on VLE with ZOOM support was user friendly. Ninety percent of the class was supportive of the continuing with the online assessments.
Conclusion: In order to device an effective protocol for e-assessments conducting multiple trial runs, and incorporating feedback from all stakeholders is a necessity.
doi: https://doi.org/10.12669/pjms.37.4.3948
How to cite this:Fatima SS, Idrees R, Jabeen K, Sabzwari S, Khan S. Online assessment in undergraduate medical education: Challenges and solutions from a LMIC university. Pak J Med Sci. 2021;37(4):945-951. doi: https://doi.org/10.12669/pjms.37.4.3948
This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Antithrombotic therapy in COVID-19
Authors: Saeed Sahrai , Bleie Øyvind 
Published: April 2021

doi: https://doi.org/10.12669/pjms.37.4.4607
How to cite this:Saeed S, Bleie Ø. Antithrombotic therapy in COVID-19. Pak J Med Sci. 2021;37(4):931-932. doi: https://doi.org/10.12669/pjms.37.4.4607
This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
The Informational Content of High-Frequency Option Prices
Authors: Amaya Diego , Bégin Jean-François , Gauthier Geneviève 
Published: April 2021

We propose the option realized variance as an observable variable to summarize the information from high-frequency option data. This variable aggregates intraday option returns from midquote prices to compute an option’s total variability for a given day, providing additional information about the jump activity in the data generating process. Using the S&P 500 index time series and options data, this paper documents the performance of this realized measure in predicting the index realized variance as well as the equity and variance risk premiums. We estimate an option pricing model and analyze its parameter estimates. Our results show that excluding high-frequency option information produces significant differences in variance jump parameters, estimated risk premiums, and option pricing errors.This paper was accepted by Tyler Shumway, finance.
A systematic literature review of incidence and predictors of headache and migraine in survivors of haemorrhagic stroke
Authors: Jones Rachael Suzanne 
Published: April 2021

Background: Headache is a frequent symptom of stroke, but little is known about the true incidence of headache following a haemorrhagic stroke, or if there are any risk factors for experiencing stroke-related headache. A systematic literature review was undertaken to examine the burden of headache in haemorrhagic stroke. Methods: A systematic search of electronic databases, including MEDLINE, CINAHL, Embase, SAGE Premier, Wiley Online Library and Elsevier's ScienceDirect, with a date range of January 1990 to October 2016, for human subjects and written in English was performed. Study selection using clear criteria was undertaken, and data extraction and assessment of quality was performed. Results: Some five from a total of 27 studies met the selection criteria. A total of 483 participants were included. The pooled random effects model showed 0.5528 (95% CI 0.3756-0.7235) had headache at onset, and 0.3917 (95% CI 0.1156-0.7108) had long-term headaches. A pooled estimate for gender as a risk factor showed women had an odds ratio (OR) of 1.93 (95% CI 1.16-3.22). Conclusions: Approximately 55% of patients with intracranial haemorrhage will experience headaches at stroke onset, with a further 39% experiencing long-term headaches. Women are nearly twice as likely as men to experience headache post-intracranial haemorrhage.