Excessive Crowding Research Articles

Investment Behavior under Uncertainty in Number of Competitors

One explanation for why investors crowd into a given strategy, as in the Quant Crisis of 2007, even when they understand its negative implication is that they are often simply not aware of the extent of crowding. In this paper, we build a simple model that formalizes this intuition. To derive excessive crowding, our model relies on two ingredients: (i) an investor’s investment decision imposes a negative externality on other investors, and (ii) investors are uncertain about the amount of competing capital at play. The model then allows us to analyze regulations regarding disclosure of capital committed to a strategy. Interestingly, we nd that it is suboptimal to disclose the amount of capital perfectly to the investors to mitigate the crowding, and that there is a case for strategic blocking of the information. We show that the implementation of the optimal disclosure policy requires a commitment device without which there occurs a policy trap.

Catastrophic payments for health care among households in urban Tamil Nadu, India

AbstractUrban residents in India face important health problems due to unhygienic conditions, excessive crowding and lack of proper sanitation. The private sector has started occupying the centre stage of the health system and households are burdened with increasing levels of health expenditure. This paper aims to study out‐of‐pocket expenditure (OOPE) and the extent of catastrophic payments for health care among households in a highly urbanised state, Tamil Nadu. The study used data on morbidity and health care for the year 2004 collected by the National Sample Survey Organization, India. Care was sought for 84 per cent of illness episodes in urban areas, and the majority used private sector providers (67 per cent for inpatients and 78 per cent for outpatients). Mean OOPE for inpatients and outpatients was higher for households with higher income. The average cost burden per visit was higher among those who sought care from private providers for inpatient services (29 per cent of household consumption expenditure) and outpatient services (20% of household consumption expenditure) compared with the burden associated with public health service use (3–4 per cent of consumption expenditure). About 60 per cent of households which used private health services faced catastrophic payments at the 10 per cent threshold level. To avoid catastrophic expenditure, greater use of the public sector which is providing services at an affordable cost is needed. Improving access to public health services, better gate‐keeping systems, stronger controls on drug prices and increasing the quality of services are required to reduce the incidence of catastrophic expenditure both on inpatients and outpatients. Greater use of risk pooling mechanisms would encourage the poor to seek health care and also to protect households from all socio‐economic groups from catastrophic expenditure. Copyright © 2009 John Wiley & Sons, Ltd.

Seasonality in rural tourism – the case of North Portugal

PurposeIn this paper, the aim is to discuss and analyze seasonality of demand within the rural tourist market of North Portugal and corresponding destination marketing implications.Design/methodology/approachThe data (n=2280) were collected through a large‐scale survey in the context of a study of the rural tourist market in North Portugal, from 1998 to 1999.FindingsResults reveal statistically significant differences between those coming in the high versus low season, concerning tourist profile, travel behavior, motivations and perceptions of the destination.Research limitations/ implicationsThe study results may only be valid for the specific rural region studied, which would make replication studies in other rural destinations desirable to take more generalizable conclusions.Practical implicationsUnderstanding seasonal market differences and confronting them with the destination's resources may contribute to the development of more attractive products and correspondingly to the destination's ability to attract and satisfy different types of tourists in different seasons of the year. The capacity to thereby improve the destination experience in the eyes of its tourists and to also manage demand, avoiding excessive crowding in the high season and eventually sub‐optimal use of resources in the low, may be an important step for maintaining a sustainable tourism business in rural areas.Originality/valueThe paper aims at contributing to the discussion of how to cope with seasonality of tourist demand, considering particularly the specificity of rural destinations and the global aim of sustainable destination development.

Image segregation in strabismic amblyopia

Humans with naturally occurring amblyopia show deficits thought to involve mechanisms downstream of V1. These include excessive crowding, abnormal global image processing, spatial sampling and symmetry detection and undercounting. Several recent studies suggest that humans with naturally occurring amblyopia show deficits in global image segregation. The current experiments were designed to study figure–ground segregation in amblyopic observers with documented deficits in crowding, symmetry detection, spatial sampling and counting, using similar stimuli. Observers had to discriminate the orientation of a figure (an “E”-like pattern made up of 17 horizontal Gabor patches), embedded in a 7 × 7 array of Gabor patches. When the 32 “background” patches are vertical, the “E” pops-out, due to segregation by orientation and performance is perfect; however, if the background patches are all, or mostly horizontal, the “E” is camouflaged, and performance is random. Using a method of constant stimuli, we varied the number of “background” patches that were vertical and measured the probability of correct discrimination of the global orientation of the E (up/down/left/right). Surprisingly, amblyopes who showed strong crowding and deficits in symmetry detection and counting, perform normally or very nearly so in this segregation task. I therefore conclude that these deficits are not a consequence of abnormal segregation of figure from background.

An Algorithm for Localised Contour Removal over Steep Terrain

Isolines have proved to be a highly effective way of conveying the shape of a surface (most commonly in the form of height contours to convey geographical landscape). Selecting the right contour interval is a compromise between showing sufficient detail in flat regions, whilst avoiding excessive crowding of lines in steep and morphologically complex areas. The traditional way of avoiding coalescence and confusion across steep regions has been to manually remove short sections of intermediate contours, while retaining index contours. Incorporating humans in automated environments is not viable. This research reports on the design, implementation and evaluation of an automated solution to this problem involving the automatic identification of coalescing lines, and removal of line segments to ensure clarity in the interpretation of contour information. Evaluation was made by subjective comparison with Ordnance Survey products. The results were found to be very close to the quality associated with manual techniques.

Depicting combinatorial complexity with the molecular interaction map notation

To help us understand how bioregulatory networks operate, we need a standard notation for diagrams analogous to electronic circuit diagrams. Such diagrams must surmount the difficulties posed by complex patterns of protein modifications and multiprotein complexes. To meet that challenge, we have designed the molecular interaction map (MIM) notation (http://discover.nci.nih.gov/mim/). Here we show the advantages of the MIM notation for three important types of diagrams: (1) explicit diagrams that define specific pathway models for computer simulation; (2) heuristic maps that organize the available information about molecular interactions and encompass the possible processes or pathways; and (3) diagrams of combinatorially complex models. We focus on signaling from the epidermal growth factor receptor family (EGFR, ErbB), a network that reflects the major challenges of representing in a compact manner the combinatorial complexity of multimolecular complexes. By comparing MIMs with other diagrams of this network that have recently been published, we show the utility of the MIM notation. These comparisons may help cell and systems biologists adopt a graphical language that is unambiguous and generally understood.

Bis-bidentate vs. bis-tridentate imino-heterocycle ligands in the formation of dinuclear helical complexes of Fe(ii)Electronic supplementary information (ESI) available: atomic positions, bond lengths and angles, anisotropic thermal parameters, hydrogen atom coordinates, data collection, and crystal parameters for all crystallographically characterized complexes; NMR spectra, including COSY, and CD spectra for ligand 3 and [FeII2(3)2]4+. See http://www.rsc.org/suppdata/dt/b2/b210137h/

By reaction of the bis-bidentate imino-quinoline ligand 1 with the octahedral cation Fe2+ in a 3 ∶ 2 metal/ligand molar ratio, a partial hydrolysis of the ligands is observed instead of the formation of the expected triple helicate, due to the excessive crowding of the trans-1,2-cyclohexyl spacers. The monomeric [FeII(2)2]2+ complex is obtained, whose crystal and molecular structure have been determined, in which the amino-imino-quinoline tridentate ligands 2, originating from 1 by loss of one quinoline aldehyde, coordinate Fe2+ with a mer disposition. Double helical complexes can instead be obtained by using the bis-tridentate ligand 3, featuring the same spacer of ligand 1, i.e.trans-1,2-cyclohexyl, and two imino-phenanthroline donor sets. The spectral and electrochemical properties of the low-spin double helical [FeII2(3)2]4+ complex have been studied and compared with those of the low spin [FeII(4)]2+ complex, which can be considered the monomeric half of the helicate. Significantly enhanced kinetic inertness and resistance to oxidation were found for the double helical complex.

Intracellular pattern reversal in Tetrahymena thermophila: I. Evidence for reverse intercalation in unbalanced doublets

Homopolar doublets of Tetrahymena thermophila possess two sets of similar cell surface structures, the most prominent of which are the complex and asymmetrical oral apparatuses. These initially are located on opposite surfaces of the duplex cell, but tend to shift so that they are no longer directly opposite each other. The two sets of oral structures are then separated by one wider and one narrower arc of cell surface. When one arc becomes sufficiently narrow, a new third oral apparatus with partially reversed internal asymmetry frequently becomes interposed between the two preexisting oral apparatuses, always within the narrower arc. After this happens, the reliability of development of new oral structures, particularly of the interposed ones, is reduced. Contractile vacuole pores, typically present within both arcs of homopolar doublets, tend to disappear from the narrower arcs. This anomalous partial triplet condition appears to be a transient intermediate stage in the reversion of homopolar doublets to normal singlets. We interpret the interposition of a transient third oral system in doublets that are regulating toward the singlet state as being a consequence of reverse intercalation of new positional values subsequent to excessive crowding of the preexisting positional values. This interpretation is an adaptation of the shortest-distance intercalation rule of the polar coordinate model applied in an intracellular and morphallactic context.

Bacterial interference with coliform colony sheen production on membrane filters.

The membrane filter (MF) method for detection and enumeration of coliform bacteria in drinking water requires that the coliforms both grow and produce a green metallic sheen when the filter is incubated on modified Endo medium at 35 degrees C for 22 h. Large numbers of noncoliform bacteria, which are enumerated by the standard plate count (SPC) technique, can interfere with the detection of coliforms on MF. This paper presents quantitative evidence from laboratory experiments on the interference of specific SPC bacteria on coliform colony sheen production on MF. Pseudomonas aeruginosa and Aeromonas hydrophila caused significant reductions in Escherichia coli sheen colony counts when present at 3,000 and 220 per filter, respectively. The Flavobacterium sp. and Bacillus sp. selected for this study from SPC did not interfere with coliform colony sheen production. Excessive crowding of E. coli and Enterobacter cloacae colonies on MF also caused a reduction in the number of colonies that produced sheen. Even when there was no crowding (14 colonies per filter), only a fraction of the E. cloacae colonies produced sheen colonies on modified Endo medium.

The morphology of synaptic profiles in explants of foetal and neonatal mouse cerebral cortex maintained in a magnesium-enriched environment.

The present study examines the ultrastructure of synaptic profiles developed in explant cultures of immature mouse cerebral cortex, maintained for prolonged periods in a magnesium-rich environment. The ethanolic phosphotungstic acid method was employed in addition to conventional preparation procedures so that paramembranous densities could be clearly observed. Although presynaptic terminals were frequently packed to capacity with vesicles in cultures maintained in magnesium-rich media, there was always a proportion which contained loosely collected vesicles. Few other changes in synaptic morphology were apparent and the paramembranous densities were unaffected. The reasons for the effectiveness of the transmission block, the absence of any change in the morphology of paramembranous densities, and the excessive crowding of presynaptic vesicles are considered and discussed.

Effects of low-level x-irradiation on cat cerebella at different postnatal intervals. II. Changes in Purkinje cell morphology.

The whole-head of infant kittens was irradiated with fractionated doses of 150 R and 200 R at different postnatal intervals. Experimental age conditions consisted of an irradiated newborn, 1-week, 2-week, 3-week, and a 4-week age condition while the age of sacrifice remained constant at 70 days. The molecular layer thickness was reduced by 47% in the newborn, 40% in the 1-week group, 17% in the 2-week group, 19% in the 3-week group and by 9% in the 4-week group. An evaluation of Golgi impregnated material revealed that the dendritic arborizations of purkinje cells were consistently reduced the earlier the age at which radiation was begun. A reduction in spiny branchlets was seen in all of the experimental conditions. All experimental age conditions displayed the phenomenon of dendritic "damming" at the pial surface, which consisted of an excessive crowding of spiny branches at this level. An increased growth of the primary dendrite before branching tood place was seen in the newborn and 1-week group. This became less but was still significant in the 2-week group. A correlation of this phenomenon with the presence or lack of stellate cells is disclssed. Purkinje cells with two or more dendrites emerging from their soma were classified and analyzed separately. It was found that the primary dendritic branching in these cells often followed separate morphological patterns and appeared to be independent of each other. Climbing fibers were found to conform to the abnormal dendritic arborizations of the Purkinje cells, and were reduced in complexity in the early radiation treatment groups. This suggested that climbing fibers had no influence upon the dendritic growth pattern, but instead were under the influence of the Purkinje cell dendritic growth.

A comparative study of growth and development in Florida mosquitoes. 3. Effects of temporary crowding on larval aggregation formation, pupal ecdysis and adult characteristics at emergence.

Temporary excessive crowding of larvae resulted in the formation of different types of species-specific aggregations under different nutritional states in 9 of the 10 species of mosquitoes investigated at a constant temperature of 27°C under LD 12:12 regime. Aggregation formation in different species was associated with modified patterns of pupal ecdysis in only 2 of the 10 species, e.g., C. p. quinquefasciatus and P. ferox. Temporary crowding in 9 of the 10 species enhanced synchronization of brood development as well as the number of pupae in individual peaks. The only exception was C. bahamensis , in which temporary crowding asynchronized development. temporary excessive crowding in 8 of the 10 species investigated, exceptions being C. bahamensis and A. aegypti , also affected the adult characteristics at emergence, with the result that the wing loading in these species was substantially lower than under standard rearing conditions. Comparison of these results with the recent studies on A. taeniorhynchus suggests that temporary excessive crowding during larval stages in 8 of the 10 species, exceptions being C. bahamensis and A. aegypti , could produce adults with the potential for exhibiting migratory behavior at emergence.

Acute ultrastructural changes in the rat olfactory glomeruli after peripheral deafferentation

Acute terminal degeneration has been studied in rat olfactory glomeruli after disconnection of the first nerve. At the 48-hour period, densification of some terminals was apparent at the electron microscopical level. This densification is due to an excessive crowding of vesicles, and to a densification of axoplasm and mitochondria. Other alterations recorded were a hyperplasia of neurofilaments isolated or associated to terminal densification, and the occurrence of diverse membranous arrays. At the 3-day period many degenerating terminals have been already engulfed by astrocytic processes. In general, the “en masse” degeneration of groups of neighboring terminals was the rule. Some images suggestive of post-synaptic dendrite involvement were also recorded.

Search for Faint OB Stars in the Southern Milky Way.

view Abstract Citations References Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Search for Faint OB Stars in the Southern Milky Way. Bok, Bart J. ; Basinski, Jane M. Abstract The new 40-in. reflector for Siding Spring Observatory arrived in Sydney late in January and has been in full operation at the Observatory since early in March. One of its first projects has been the photography of six southern Milky Way fields as a part of a search program for faint early-type stars in the range of apparent magnitude 10 to 15. The search technique is basically that employed earlier at Tonantzintla Observatory. Each photograph on a 103aD emulsion contains three (or more) successive exposures, through a UG2, a GG 13 and a GG 14 filter. Thus are reproduced stellar images on a color system approximating U, B, and V. The 0, B, and A stars are readily located from these plates and their U, B, and V magnitudes and colors are then measured with the aid of single-image 103aO and 103aD plates obtained with the appropriate filters. All of the six are fields for which B. J. Bok and P. F. Bok have now available standard UB V photoelectric sequences to V= 14 or 15, and these sequences permit us to determine precise magnitudes and colors photographically. One of the problems encountered in the rich southern Milky Way fields is that of excessive crowding of the multiple image plates. To supplement the 103aD plates, we have therefore taken on each field a 103aO search plate with two images only, one a 20-min exposure through a UG2 filter, the other a 5-min exposure through a GG 13 filter. Stars with U-B = 0.00 show two images of roughly equal size, stars with U-B <0.00 have a larger U image than a B image. It should be possible to extend the search without much difficulty to V =17, provided good standard photoelectric sequences are available. Publication: The Astronomical Journal Pub Date: 1964 DOI: 10.1086/109385 Bibcode: 1964AJ.....69Q.533B full text sources ADS |

A Container for the Transport of Insect Cocoons or Pupae

The methods of despatching insects from one country to another for biological control purposes have often left much to be desired. When insects are sent as pupae or cocoons, they are generally packed in damp wood-wool or sphagnum moss to absorb vibration, from which it is often difficult to remove either the insects or any undesirable fellow travellers.The ideal insect container should be strong, light in weight, small enough for ease of handling, yet able to hold large numbers of individuals without excessive crowding.

STUDIES ON THE HOUSEFLY (MUSCA DOMESTICA L.): I. THE BIOLOGY AND LARGE SCALE PRODUCTION OF LABORATORY POPULATIONS

Using the Peet-Grady method for propagating houseflies required as biological test animals, variations were observed that had considerable bearing on production and subsequent adult life. Differences in length of life, fecundity, time of emergence of the adults from puparia, and the onset of egg laying occurred between different populations of flies. Investigations were carried out to determine the extent and causes of the variations and to develop more suitable techniques for producing large numbers on a more accurately predictable basis. Variability in production of puparia was found to be due largely to the age of female stock and rate of fermentation in the rearing medium through their effects on egg hatchability and larval survival and excessive crowding caused by high temperatures. By using eggs from genetically-selected stock of known age and rearing in a temperature-controlled medium, production of flies was increased and maintained at a constantly uniform rate. A description is given of the equipment and methods used.

PREVENTIVE MEDICINE PROBLEMS PECULIAR TO THE PACIFIC COAST

Health problems all over the United States are similar, but in different areas the magnitude of the problems vary to a considerable degree. Malaria, for instance, a real problem in the South, is not one in the Northwest. Botulism, there almost an unknown disease, is the subject of continuous investigation in the West. It is well known that the virulence of the ordinary communicable diseases varies in different sections, and it is possible that individuals living in a certain environment may have an increased resistance to these diseases that they would not possess if they lived elsewhere. I have been asked many times why the mortality rate in communicable diseases is so low in the Northwest. It is not because of acquired immunity, as the slums and excessive crowding of the East are not in evidence. It is true that the Western people, having come largely from the older sections

An Attempt to deduce the Vertebrate Eyes from the Skin

ABSTRACT In the February issue of the ‘Annals and Magazine of Natural History ‘I published an outline sketch of a new theory of vision. It was suggested that eyes arose as local modifications of tissue induced by the excessive crowding of pigmented granules at spots most frequently and brilliantly illuminated, and that this crowding of the pigmented granules might be made to explain both the origin of the eye as a structure and its functions as an organ. I now propose, as time and opportunity allow, to compare a few eyes with the tissues out of which they have, or according to the theory they should have, arisen, in order to ascertain how far such comparisons support the theory.