High Crowd Research Articles

Effect of Crowding on Protein–Protein Association Rates: Fundamental Differences between Low and High Mass Crowding Agents

Physiological media constitutes a crowded environment that serves as the field of action for protein–protein interaction in vivo. Measuring protein–protein interaction in crowded solutions can mimic this environment. In this work we follow the process of protein–protein association and its rate constants ( k on) of the β-lactamase (TEM)–β-lactamase inhibitor protein (BLIP) complex in crowded solution using both low and high molecular mass crowding agents. In all crowded solutions (0–40% (w/w) of ethylene glycol (EG), poly(ethylene glycol) (PEG) 200, 1000, 3350, 8000 Da Ficoll-70 and Haemaccel the measured absolute k on, but not k off values, were found to be slower as compared to buffer. However, there is a fundamental difference between low and high mass crowding agents. In the presence of low mass crowding agents and Haemaccel k on depends inversely on the solution viscosity. In high mass polymer solutions k on changes only slightly, even at viscosities 12-fold higher than water. The border between low and high molecular mass polymers is sharp and is dictated by the ratio between the polymer length ( L) and its persistence length ( L p). Polymers that are long enough to form a flexible coil ( L/ L p>2) behave as high molecular mass polymers and those who are unable to do so ( L/ L p<2) behave as low molecular mass polymers. We concluded that although polymers solution are crowded, this property is not uniform; i.e. there are areas in the solution that contain bulk water, and in these areas proteins can diffuse and associate almost as if they were in diluted environment. This porous medium may be taken as mimicking some aspects of the cellular environment, where many of the macromolecules are organized along membranes and the cytoskeleton. To determine the contribution of electrostatic attraction between proteins in crowded milieu, we followed k on of wt-TEM and three BLIP analogs with up to 100-fold increased values of k on due to electrostatic steering. Faster associating BLIP variants keep their relative advantage in all crowded solutions, including Haemaccel. This result suggests that faster associating protein complexes keep their advantage also in complex environment.

Comprehensive coupled reversed-phase reversed-phase separations of a complex isomeric mixture

Using predictions based on results obtained from Information Theory and Factor Analysis for the two-dimensional separation of a complex isomeric mixture, a practical experimental comprehensive coupled reversed phase-reversed phase chromatographic system was developed. In total four reversed phase-reversed phase systems were studied, each of which theory predicted would be able to resolve essentially equal numbers of components. However, in practice only one of these coupled systems realised the theoretical potential. This system employed as the first dimension, a C18 stationary phase with methanol as the mobile phase and as the second dimension, carbon clad zirconia as the stationary phase and acetonitrile as the mobile phase. In this system, 27 of the 32 isomers of a mixture of oligostyrenes were resolved. Failure of the remaining coupled systems to achieve the theoretical potential was attributed to high solute crowding, low efficiency of separation space utilisation and long analysis times in the second dimension.

Evaluation of short duration ICRISAT pigeon pea cultivars in mixtures with FARZ-7 maize under the derived savannah conditions of Nigeria

Three ICRISAT short duration pigeon pea cultivars namely: ICPL84023, ICPL151, and ICPL87, were evaluated in intercropping system with FARZ-7 maize for growth, grain yield, and intercropping benefits at the University of Nigeria Teaching and Research Farm in the early cropping season of 1993. Intercropping any of the short duration pigeon pea cultivars with FARZ-7 maize was more beneficial than planting maize or pigeon pea sole. Although intercropping depressed grain yield of short duration pigeon pea by 20 to 58% of its sole, in terms of land equivalent ratio (LER), intercropping benefits ranged from 1.33 to 1.77, the highest being with ICPL87 + maize intercrop. ICPL151 and ICPL87 were bigger plants in intercrop with higher relative crowding coefficients (RCC) than ICPL84023. But ICPL151 and ICPL84023 were able to compete better with maize than ICPL87. The yield advantage observed with ICPL87 + maize was due to the extra yield of maize in that mixture. Maize was in all cases the dominant component of the mixture having higher relative crowding coefficient, and competition coefficient values than the pigeon pea cultivars. ICPL151 and ICPL84023 would be recommended for intercropping with maize because of their higher yield contribution to the overall yield, as the legume grain is of premium value compared with maize grain. [IJARD Vol.3 2002: 138-143]

The Red Stellar Population in NGC 1569

We present HST NICMOS photometry of the resolved stellar population in the dwarf irregular galaxy NGC 1569. The color-magnitude diagram (CMD) in the F110W and F160W photometric bands contains ~2400 stars with a formal photometric error 0.1 mag down to mF110W ≈ 23.5 and mF160W ≈ 22.5. The fiducial photometry has a completeness factor higher than 50% down to mF110W ≈ 21.5 and mF160W ≈ 20.0. We describe the data processing required to calibrate the instrumental peculiarities of NICMOS. Two different packages (DAOPHOT and StarFinder) for PSF-fitting photometry are used to strengthen the photometric results in the crowded stellar field of NGC 1569. The resulting CMD is discussed in terms of the major evolutionary properties of the resolved stellar populations. For a distance modulus of (m - M)0 = 26.71 and a reddening of E(B-V) = 0.56, our CMD samples stars down to ~0.8 M⊙, corresponding to look-back times of more than 15 Gyr (i.e., an entire Hubble time). This is a clear indication of star formation activity in NGC 1569 spanning an entire Hubble time. The metallicity of the reddest red giant branch (RGB) stars is in better agreement with Z = 0.004 as measured in H II regions than with Z = 0.0004, as expected from the stellar ages. However, the presence of—yet undetected—very metal-poor stars embedded in the stellar distribution around mF110W = 22.75 and mF110W - mF160W = 1.15 is not ruled out. The youngest stars (50 Myr) are preferentially found around the two central super star clusters, whereas the oldest population has a more uniform spatial distribution. A star formation rate per unit area of 1 M⊙ yr-1 kpc-2 and a mass formed in stars of ~ 1.4 × 106 M⊙ in the last 50 Myr are derived from the CMD. The near-infrared (NIR) CMD places strong constraints on the lower limit of the onset of star formation in NGC 1569. The exceptionally high crowding in the NICMOS images of NGC 1569 is a challenge for photometric analysis. As a result, optical and NIR images of NGC 1569 sample different populations and cannot be cross-correlated. Nevertheless, we demonstrate the consistency of the star formation histories derived from the optical and NIR CMDs.

Modelling human behaviour within the fire risk assessment tool CRISP

CRISP is a Monte-Carlo model of entire fire scenarios. The sub-models representing physical 'objects' include rooms, doors, windows, detectors and alarms, items of furniture etc, hot smoke layers, and people. The stochastic aspects include starting conditions such as windows and doors open or closed, the number, type and location of people within the building, the location of the fire and type of burning item. The fire and smoke spread are simulated by a 2-layer zone model. The simulation uses a variable timestep in order to achieve maximum efficiency while still maintaining a numerically stable solution. People are assumed to adopt distinct behavioural roles, either naturally or due to training. Their behaviour can be described in terms of actions, which may be abandoned, and substituted by new ones, depending on the state of the environment, Rational decisions are made based on current knowledge (which may be limited and/or incorrect). Movement of people through the building firstly requires a route to be planned through the network of rooms. The choice of route is influenced by the doors' transit difficulty (modified for the presence of smoke) and the distance. Within each room, movement to the next door on the route is directed by means of a contour map of distance to go. This enables any obstacles to be avoided. Movement speed is affected by local crowd density. Deviations from the minimum distance path through a room may be made to avoid areas of high crowd density. Some of the outputs from the CRISP model are described. These include histograms of Fractional Effective Dose (FED) acquired by the occupants (from which the life risk is calculated), and profiles of the number of people remaining in the building as a function of time.

Modelling human behaviour within the fire risk assessment tool CRISP

CRISP is a Monte-Carlo model of entire fire scenarios. The sub-models representing physical ‘objects’ include rooms, doors, windows, detectors and alarms, items of furniture etc, hot smoke layers, and people. The stochastic aspects include starting conditions such as windows and doors open or closed, the number, type and location of people within the building, the location of the fire and type of burning item. The fire and smoke spread are simulated by a 2-layer zone model. The simulation uses a variable timestep in order to achieve maximum efficiency while still maintaining a numerically stable solution. People are assumed to adopt distinct behavioural roles, either naturally or due to training. Their behaviour can be described in terms of actions, which may be abandoned, and substituted by new ones, depending on the state of the environment. Rational decisions are made based on current knowledge (which may be limited and/or incorrect). Movement of people through the building firstly requires a route to be planned through the network of rooms. The choice of route is influenced by the doors' transit difficulty (modified for the presence of smoke) and the distance. Within each room, movement to the next door on the route is directed by means of a contour map of distance to go. This enables any obstacles to be avoided. Movement speed is affected by local crowd density. Deviations from the minimum distance path through a room may be made to avoid areas of high crowd density. Some of the outputs from the CRISP model are described. These include histograms of Fractional Effective Dose (FED) acquired by the occupants (from which the life risk is calculated), and profiles of the number of people remaining in the building as a function of time. Copyright © 1999 John Wiley & Sons, Ltd.

Epidemiology and control of scabies in an Egyptian village

Some studies have addressed the epidemiology of scabies among rural populations in developing countries; however, the epidemiology of scabies among the rural population in Egypt is unknown. We sought to determine the magnitude of scabies infestation in an Egyptian village and to evaluate the control measures after 1 year. This study was carried out on 3147 residents of Mit-Moaned village in Dakahlia govemorate, Egypt. It was a cross-sectional follow-up study where the same individuals examined in round I were re-examined in round III. The two rounds were separated by a period of 1 year, during which infested patients were followed up and new cases were discovered (round II). Patients and their household contacts received treatment with topical permethrin. Patients showing resistance to permethrin received a single oral dose of ivermectin. In round III, the overall prevalence rate of scabies was reduced from 5.4% in round I to 1.1%. The incidence of new cases among susceptible persons during round II was 1.1%. Scabies was significantly (P < 0.05) more prevalent among families of large size, high crowding index at night, low socioeconomic standards, and those receiving their water supply from a hand pump. Children younger than 10 years showed the highest prevalence. Our data provide the first complete picture of the epidemiology of scabies in rural Egypt. The epidemiologic characteristics of the disease should be considered in the design of disease control programs for other villages with scabies epidemics. Our findings revealed that good control was achieved with the following: increased awareness and better case finding, education of the staff at the rural health unit, improved hygiene measures, and massive treatment campaigns using effective drugs such as topical permethrin and oral ivermectin.

Children experiencing violence I: parental use of corporal punishment

Objective: This study was undertaken to reveal the prevalence of corporal punishment in Alexandria and its’ correlates with family background and child’s behavior and characteristics. Methods: A cross sectional survey targeting preparatory and secondary school children was conducted. The multistage random sample technique was adopted to select a representative sample of this population. Subjects were requested to complete a self-administered questionnaire to collect relevant information. Data were analyzed using the univariate and multivariate analyses. Results: This study revealed that more than one-third (37.47%) of children were disciplined physically in the form of beating and a few were also burned or tied. In 25.83% of them, this harsh discipline led to physical injuries of variable degrees of severity amounting to fractures, loss of consciousness, and permanent disability. Predictive family background for the use of corporal punishment were: living in an apartment shared with strangers; high crowding index; constant fights and quarrels between family members; lack of regular relation with relatives and acquaintance as well as an income insufficient to meet the family basic needs. Predictive child’s characteristics and behavior included young age; disobedience; telling lies; destroying others’ belongings; acting disrespectfully to parents; communicating poorly with their parents; running away from home; and poor school achievement, in addition to other determinants. Conclusion: A proportion of children are subjected to extreme physical brutality amounting to abuse in a disciplinary context. Parents’ education and the establishment of effective parent-child communication are deemed essential to combat this phenomenon.

A Method for Optimal Image Subtraction

We present a new method designed for optimal subtraction of two images with different seeing. Using image subtraction appears to be essential for the full analysis of the microlensing survey images, however a perfect subtraction of two images is not easy as it requires the derivation of an extremely accurate convolution kernel. Some empirical attempts to find the kernel have used the Fourier transform of bright stars, but solving the statistical problem of finding the best kernel solution has never really been tackled. We demonstrate that it is possible to derive an optimal kernel solution from a simple least square analysis using all the pixels of both images, and also show that it is possible to fit the differential background variation at the same time. We also show that PSF variations can also be easily handled by the method. To demonstrate the practical efficiency of the method, we analyzed some images from a Galactic Bulge field monitored by the OGLE II project. We find that the residuals in the subtracted images are very close to the photon noise expectations. We also present some light curves of variable stars, and show that, despite high crowding levels, we get an error distribution close to that expected from photon noise alone. We thus demonstrate that nearly optimal differential photometry can be achieved even in very crowded fields. We suggest that this algorithm might be particularly important for microlensing surveys, where the photometric accuracy and completeness levels could be very significantly improved by using this method.

Interactions among environmental enrichment, viewing crowds, and zoo chimpanzees (Pantroglodytes)

The primary purpose of this study was to investigate whether or not a group of zoo chimpanzees responded to environmental enrichment differently given higher weekend crowds in contrast to lower weekday crowds. Findings showed that foraging, feeding, and object-using were more likely with new enrichment; conversely, grooming, playing, watch-idle, and aberrant behaviors were more likely with 1 day-old enrichment. Across both new and 1 day-old enrichment, however, high crowds corresponded with diminished frequencies of foraging, object-using, grooming, and play. The study's second purpose was to examine how zoo visitors responded to chimpanzees under varying conditions of environmental enrichment. Analysis of zoo visitors' verbatim responses suggested that the public's behavior was influenced by desires to interact with the chimpanzees, the state of the chimpanzees' habitat, the relative complexity of the chimpanzees' activities, and human sociocultural norms. Thus a variety of contextual factors were found to influence the behavior of chimpanzees and humans alike. Future research is encouraged that investigates the ways in which multiple elements within the full captive socioecology of chimpanzees fluidly interact to influence the effectiveness of environmental enrichment as well as zoo visitors' responses to, and lasting impressions of, zoo chimpanzees. Zoo Biol 17:211–230, 1998. © 1998 Wiley-Liss, Inc.

Treatment of a patient with a Class II malocclusion and an extremely high mandibular plane angle and severe crowding

This case report was presented to the American Board of Orthodontics as partial fulfillment of the requirements for the certification process conducted by the Board. (Am J Orthod Dentofac Orthop 1997;111:93-9.)

Environmental Factors Affecting Wing Length Variation of a Stink Bug, Pyrrhocoris sibiricus (Heteroptera: Pyrrhocoridae)

Adults of a stink bug, Pyrrhocoris sibiricus, were collected from natural populations and investigated for wing length variation. The environmental factors (nymphal density, temperature and photoperiod conditions) affecting wing length variation were also investigated in the laboratory. Adults were collected in Okayama, western Japan, from July to September of 1991. To clarify the effect of nymphal density, first-instar nymphs were reared at densities of 1, 2, 4, 8 and 16 individuals per Petri dish (9 cm in diameter, 2cm in depth) under 16L-8D at 30°C. The effect of temperature was investigated by rearing first-instar nymphs at 20, 25 and 30°C under 16L-8D at a nymphal density of 8 individuals. To clarify the effect of photoperiod, first-instar nymphs were reared under 8L-16D, 12L-12D and 16L-8D at 30°C at a nymphal density of 8 individuals. The relative forewing length (RFL) and relative hindwing length (RHL) of adults collected from the field were continuously distributed in both sexes. Environmental factors such as high temperature, short day-length and moderate crowding tended to promote the production of longer hindwinged adults, although no decisive factors were determined.

Dialect differences in vowel production and perception

Earlier work [Faber etal., J. Acoust. Soc. Am. 94, 1865 (1994)] reported differences among American-English-speaking listeners from Utah and Connecticut/NY in perception of the HEEL–HILL and POOL–PULL contrasts (pairs that are nearly merged in Utah but distinct in the northeast US), measured by three tasks, labeling, AXB discrimination, and keyword identification. On these tasks, a few CT/NY listeners (those with parents from the southern US) performed differently from the other subjects. Their vowel spaces also were qualitatively different from those of the other listeners, based on acoustic analysis of three readings of the keywords. The CT/southern listeners had more high back crowding and did better on Utah POOL/PULL than the other listeners, while the Utah listeners had more high front crowding and did better on Utah HEEL/HILL. These results accord with the literature reviewed by Bradlow [Cross-LinguisticStudyofVowelInventories, Cornell (1993)] relating listeners’ ability to discern small vowel differences to the number of vowels in their language, but were tentative because of the small number of CT/southern subjects. The current study presents perception and production data from additional Connecticut/NY subjects confirming the original finding. [Work supported by NIH.]

Habitat stability and the larval mosquito community in treeholes and other containers on a temperate Island

AbstractThe temporal fluctuation of water levels and the presence of mosquito larvae were investigated for four types of small container habitats (treeholes, bamboo stumps, cemetery stone vases, and cemetery stone vessels) on Kabeshima Island in Kyushu, southwestern Japan. The probability that containers held water was positively correlated with the quantity of the preceding rainfall and with the depth and volume of the containers. It was estimated that dehydration occurred more regularly in autumn and winter than in summer. The probability that mosquito larvae were present in each type of container was positively correlated with habitat stability in terms of the probability of the existence of standing water and the coefficient of variation of the water level. Twelve species of mosquito larvae, including two rare predators, were found. Species composition differed between the different types of container. Although 4 to 10 species used each type of container, the median number of species per container was two for treeholes and bamboo stumps, and one for the others. The dominant species was Tripteroides bambusa in treeholes and bamboo stumps, Aedes albopictus in stone vases, and A. japonicus in stone vessels. The larval mosquito community, which lacked major predators, possessed the following features that may facilitate the coexistence of many species: (1) niche segregation amongst species in terms of their selection of container types; (2) an aggregated distribution of the individual species among containers of the same type; (3) high intraspecific mean crowding (and hence probably intense intraspecific competition) in the dominant species in each type of container; (4) independent species associations within the same type of container; and (5) low interspecific mean crowding (and hence probably not intense interspecific competition) between species in the same type of container.

The Component of Gaze Selection/Control in the Development of Visual Acuity in Children

Visual acuity was tested for 180 eyes of 90 children in four age groups using three types of test charts. Subjects read the same 10 high-contrast letters in Snellen (line) format, as isolated-letter flash cards, and as repeat-letter flash cards. Group mean line and group mean isolated-letter acuity showed similar progressive improvements with age. A subgroup of 24 of 50 eyes of 4- to 5-year-olds (15 of 25 subjects) and 3 of 50 eyes of 6- to 7-year-old (2 of 25 subjects) had low Snellen acuity. Of this low-acuity subgroup of 27 eyes, 10 scored above average for their age group on the repeat-letter chart. We concluded that abnormal lateral interactions were not the explanation for the immaturity of Snellen acuity in these 10 eyes. We suggest that an important factor in the low acuities of these 10 eyes is delayed development of the selection and/or control of gaze direction. Some eyes with excellent Snellen acuity showed high crowding. For example, there were five such eyes in the oldest group. We suggest that the excellent acuities of at least two of these eyes are limited by minor inaccuracies in gaze selection and/or control rather than by lateral interaction.

Influence of adolescent social crowds on the development of vocational identity

A major gap in Holland's theory of vocational identity has been specification of the developmental antecedents of the six personality types. The present paper extends Geoffrey Kelso's work on the developmental antecedents of Holland's types by examining the relationship between membership in adolescent social crowds and vocational identity in early adulthood. In four samples (total N = 274), membership in five junior high school crowds—Motorheads, Brains, Freaks, Politicos, and Conformists—was found to be associated with higher scores on the Realistic, Investigative, Artistic, Enterprising, and Conventional scales, respectively, of Holland's Self-Directed Search and Vocational Preference Inventory in early adulthood. The relative impact of temperament, family, and peer variables on the development of vocational identity is discussed.

EFFECTS OF PROLONGED COLONIZATION, CROWDING, AND STARVATION ON DEVELOPMENT AND SURVIVAL RATES OF CABBAGE LOOPERS, TRICHOPLUSIA NI (HUBNER) (LEPIDOPTERA: NOCTUIDAE)

The effect of colonization, crowding, and starvation on the development of cabbage looper, Trichoplusia ni, was investigated. Differences in development time, pupal weight, mortality rate, and adult longevity between a laboratory and field colony were minimal. These differences are believed to be correctable through minimization of selection and precautions against pathogenic contamination during rearing, as well as, regular introduction of field collected insects into the laboratory colony. Stress produced by larval crowding and starvation in the laboratory colony produced a longer development time, increased mortality, and reduced pupal weight. Cannabalism of larvae, prepupae, and pupae was noted at higher crowding and starvation (stress) levels. Increased adult longevity at higher stress levels was also observed.

Crowding and reactions to uncontrollable events

The current study sought to test the consequences associated with misattributing uncontrollable events to crowding. Results showed that when density is a salient cue, greater crowding attributions were made when individuals were exposed to uncontrollable as opposed to controllable outcomes. In addition, performance deficits were found for individuals who were exposed to uncontrollable outcomes, indicated high crowding, and were administered a subsequent task in a nondense setting. The results are discussed in relation to the learned helplessness model as well as studies investigating the aftereffects of stress on human performance.

Elimination–addition mechanisms of acyl-group transfer: the neutral and alkaline decomposition of 1-(N-methylcarbamoyl)imidazoles

Aqueous hydrolysis of 1-(N-methylcarbamoyl)imidazoles exhibits a pH-dependence consistent with E1cB pathways through neutral and cationic forms of the substrate. The derivatives of the most basic imidazoles have the greatest overall hydrolytic reactivity. There is little steric requirement for decomposition via either mechanism despite the relatively high crowding in the most hindered species studied; the slight enhancement of the hydrolysis rate for 1-(N-methylcarbamoyl)-2,4,5-trimethylimidazole is judged to be due to a gain in rotational entropy during departure of the leaving imidazolyl group. The ionisation of imidazoles and of their conjugate acids have nearly identical selectivities to substituent change.

Rediscovering the fourth “R”

Can anyone raised in the city during the 1940s ever forget the long hours, the seemingly endless spent playing in the school yard? Everyone was there: classmates; the high school crowd who somehow disappeared at dusk into the darker recesses of the courtyard; the graduates or dropouts who couldn't find employment and returned to scenes of earlier success; firemen, usually men in their twenties, who came for something to do on days off, and, so many others who were exciting and interesting to us. They seemed almost God-like with their playing skills, polish, and city-wise way of knowing just how safe a smart remark might be in any circumstance.