bluuebunny/crossref_metadata_2025 huggingface dataset:
On the Physical Nature of Time
Authors: Harrison Edward
Published: October 2002

It is argued that certain characteristics of time, normally ascribed to the observer, are actually properties of the natural world, and hence the natural world (physical reality) is more complex than normally supposed. Everything extends in time. Events stretch away into the recent past as recalled in our memories and recorded in daily newspapers, and into the distant past as recounted by historians, paleontologists, and geologists. Events also stretch away into the near future as anticipated in our plans and foretold by weather forecasters, and into the distant future as predicted by climatologists, geologists, and astronomers. Everything also occurs in time. Events happen either quickly or slowly. The glacier takes centuries to reach the sea and the lightning stroke zig-zags to earth faster than the eye can see. Events occupy time and also occur in time; and their occupation and occurrence in time are not the same thing. The extension of time and the transience of time are different aspects of time that in thought, language, and science remain unreconciled. Here I discuss how these two fundamental aspects of time can be reconciled and included in the physical world description. I take the view that both are equally important properties of the natural world and speculate on how the physical world picture would change by their joint incorporation. A theory of "conjugate time" is tentatively proposed.
JUSTICE IN JUDAISM: THE CASE OF JONAH
Authors: Levine Étan
Published: September 2002

He who knows only his side of the case knows little of that. John Stuart Mill, On Liberty (1859)
A modelling method for building-integrated photovoltaic power supply
Authors: Jones A D , Underwood C P
Published: September 2002

Models of photovoltaic (PV) module electrical characteristics are well developed, because of the precise knowledge of the physics of semiconductor behaviour. The PV cell current-voltage characteristic is well known, and used in many models of array output. However, in many practical cases such as building-integrated photovoltaics, a model of power output only is required. Current-voltage revious researchers on which particular model should be used. This contrasts with the case of the diode model for I-V characteristics. In this work, an ef. ciency model of power output will be developed based on an adaptation of the established PV. fill factor method, and attempts are made to ground the irradiance and temperature characteristics in established theory in order to make a general PV power ef. ciency model. The model is validated using measured data from a 39.5-kW building-integrated PV array.
Late Holocene Vegetation Change in the Sierra Madre Oriental of Central Mexico
Authors: Conserva Maria Elena , Byrne Roger
Published: September 2002

Past vegetation and climate changes reconstructed from a sediment core from Laguna Atezca, Molango, Mexico, provide new insights into the environmental and cultural histories of the Sierra Madre Oriental during the last 1700 yr. Pollen, microscopic charcoal, sediment chemistry, loss on ignition, and magnetic susceptibility indicate that three phases of human occupation, deforestation, and erosion (ca. A.D. 280–890, ca. A.D. 1030–1420, and ca. A.D. 1680–present) alternate with two phases of abandonment (ca. A.D. 890–1030 and ca. A.D. 1420–1680). Forest composition of the two abandonment phases differed, with cloud forest taxa (Liquidambar, Ostrya/Carpinus, Ulmus, etc.) dominating the pollen record during the first phase, andQuercusandPinuspollen characterizing phase two. These differences may reflect a climate change in which the second phase was drier than the first; Alternatively, the increase inPinusandQuercusmay have been caused by a human-induced decline in soil fertility. The Laguna Atezca record also differs from several other Mesoamerican paleoenvironmental records in that it shows no evidence of drought at the end of the Classic Period, ca. A.D. 900.
Paleoenvironmental Changes in the Semiarid Coast of Chile (∼32°S) during the Last 6200 cal Years Inferred from a Swamp–Forest Pollen Record
Authors: Maldonado Antonio , Villagrán Carolina
Published: September 2002

Pollen analysis of two sediment records from a coastal swamp forest site in the Chilean semiarid region (31°50′S; 71°28′W) shows an alternation of dry and wet phases during the past ∼6100 cal yr B.P. The most prominent vegetation changes occur at ∼4200 cal yr B.P., with the expansion of the swamp forest taxa Luma chequen and Escallonia sp., followed by a regression of the forest beginning at ∼3200 cal yr B.P. and ending with its replacement by a xerophytic scrub, between ∼1800 and 1300 cal yr B.P. The swamp forest reexpanded after ∼1300 cal yr B.P. and persisted, with minor variation, until the present. We interpret the establishment of the swamp forest at the study site to be the result of a rising watertable in response to increased rainfalls from ∼4200 cal yr B.P. onward. Our results indicate that in north-central Chile the second half of the Holocene was climatically more variable than previously thought, suggesting significant changes in the position and/or intensity of the westerlies wind belt and possibly in the frequency of El Niño–Southern Oscillation events.
A Test of “Annual Resolution” in Stalagmites Using Tree Rings
Authors: Betancourt Julio L. , Grissino-Mayer Henri D. , Salzer Matthew W. , Swetnam Thomas W.
Published: September 2002

So-called annual banding has been identified in a number of speleothems in which the number of bands approximates the time interval between successive U-series dates. The apparent annual resolution of speleothem records, however, remains largely untested. Here we statistically compare variations in band thickness from a late Holocene stalagmite in Carlsbad Cavern, Southern New Mexico, USA, with three independent tree-ring chronologies form the same region. We found no correspondence. Although there may be various explanations for the discordance, this limited exercise suggests that banded stalagmites should be held to the same rigorous standards in chronology building and climatic inference as annually resolved tree rings, corals, and ice cores.
Implications of Water Supply for Indigenous Americans during Holocene Aridity Phases on the Southern High Plains, USA
Authors: Wood Warren W. , Stokes Stephen , Rich Julie
Published: September 2002

Springs in the 40 to 50 large lake basins (>15 km2) on the southern portion of the Southern High Plains (SHP) were active during periods of aridity in the Holocene when there may have been human habitation of the area. Eolian erosion of the lake floors and lunette accretion occurred as groundwater levels declined in response to decreased groundwater recharge. The declining lake floor associated with eolian erosion allowed groundwater evaporative discharge to continue, thus maintaining a groundwater gradient toward the lake. This hydrologic condition was favorable for a relatively continuous spring discharge to the lake, independent of the elevation of the lake floor. To evaluate the postulated dynamic equilibrium critical to this conclusion, 17 optically stimulated ages were determined from a 17.7-m deep core of a lunette adjacent to Double Lakes, Texas (33°13′15″N, 101°54′08″W). The core yielded sediment accumulation dates of 11,500±1100, 6500±700, and 4900±500 yr B.P., corresponding broadly with periods of aridity known from other evidence. Based on analysis of this lunette, it is concluded that springs in Double Lakes basin probably existed throughout the Holocene with discharges similar to those observed historically. We assumed that similar dynamic equilibrium existed in the other large lake basins in the SHP and that these springs could have provided a continuous source of water for indigenous peoples during periods of prolonged aridity. The dynamic equilibrium that is proposed in this study is applicable not only to other arid and semiarid geographic areas with wind-erodible material but also over different geologic times.
Zooarchaeological Evidence of Prairie Taxa in Central Missouri during the Mid-Holocene
Authors: Wolverton Steve
Published: September 2002

Previous studies report that remains of prairie taxa are common in western Missouri archaeological sites. There is no reported evidence of prairie taxa, such as Bos bison, from sites within the northern Ozark Highlands of Missouri. New data indicate that prairie taxa inhabited the area during the warm and dry mid-Holocene (8500–5000 14C yr B.P.). Evidence suggests prairie taxa were farther east and south than previously documented in central Missouri and underscores the importance of biogeographic data in studies of prehistoric environments.
Early to Mid-Holocene Aridity in Central Chile and the Southern Westerlies: The Laguna Aculeo Record (34°S)
Authors: Jenny Bettina , Valero-Garcés Blas L. , Villa-Martínez Rodrigo , Urrutia Roberto , Geyh Mebus , Veit Heinz
Published: September 2002

Central Chile (32–35°S) lies at the northern border of strong Westerly influence and thus exhibits a steep precipitation gradient. Therefore, the palaeoclimatic archives in the region are suitable for detecting past moisture changes. The study of Laguna Aculeo (33°50'S, 70°54'W) presents a multiproxy Holocene lake record including sedimentology, geochemistry, mineralogy, pollen, diatoms, and radiocarbon dating (17 dates). Results indicate an arid early to mid-Holocene period (about 9500–5700 cal yr B.P.). After 5700 cal yr B.P. effective moisture increased progressively and around 3200 cal yr B.P., modern humid conditions were established. Numerous intercalated clastic layers reflect flood deposition during rainy winters. A fluvial unit was deposited shortly before 9000 cal yr B.P. Subsequently, flood events were absent until 5700 but have become frequent since 3200 cal yr B.P. The frequency of flood layers possibly points to weak or no El Niño activity during the early and mid-Holocene, with a subsequent increase during the late Holocene. During the early and mid-Holocene, the Westerlies were probably blocked and hence deflected southward by the subtropical high-pressure cell. Higher precipitation during the last 3200 yr seems strongly related to a weakened subtropical high-pressure cell with intensified Westerlies and possibly increased El Niño activity.
Hypogonadotropic hypogonadism: retrospective analysis of 19 cases
Authors: Moura M.D , Navarro P.A.A.S , Silva de Sá M.F , Ferriani R.A , Unzer S.M , Reis R.M
Published: September 2002

Objectives: To survey the clinical data of patients with isolated gonadotropin deficiency. Methods: We retrospectively surveyed the medical records of 19 patients with isolated gonadotropin deficiency aged 16–31 years (mean: 20 years). The major complaint was primary amenorrhea in 100% of the patients, with 42.1% of them also reporting absence of secondary sex traits, and 10% reporting anosmia or hyposmia. Seventy‐four percent of the patients had been submitted to hormonal replacement therapy. Results: Bone densitometry was determined in 5 patients and revealed lumbar spine osteopenia in 3 patients and femoral osteopenia in 1. An association with urologic malformations was detected in 10.5% of cases and an association with gynecologic malformations was detected in 31.6%. Conclusions: Isolated gonadotropin deficiency can be easily diagnosed but requires early estrogen replacement therapy because of a higher risk of osteopenia and consequently of osteoporosis. Concomitant urogenital malformations are frequent and should be investigated.
From the Editor Vol 5 No 2
Authors: Lahey Karen Eilers
Published: September 2002

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Risk Aversion Measures
Authors: Schooley Diane K. , Worden Debra Drecnik
Published: September 2002

Households’ reported willingness to take financial risk is compured to the riskiness of their po~olios, measured as risky assets to wealth. Overall, their ~or~olio alio~ations are reliable indicators of attitudes toward risk, demonstrating an understanding of their relative level of risk taking. Multivariate regression analysis using multiply imputed data from the 1989 Survey of Consumer Finances indicates that households generally exhibit decreasing relative risk aversion. Further, investment in risky assets is significantly related to socioeconomic factors, attitude toward risk taking, desire to leave an estate, and expectations about the adequacy of Social Security and pension income.
Personal Finance
Authors: Vihtelic Jill Lynn
Published: September 2002

Effective teaching invites students into the discipline and helps them to see and make connections between the discipline’s content and their lives. This paper identifies an alternative approach to effective teaching of undergraduatefinance. Personalfinance, as opposed to managerialfinance, provides a more appropriatefoundation on which to center the undergraduate$nance curriculum. It better matches students’ interests, per- sonal experiences, and cognitive structures. This paper takes the position that personal finance should precede managerial finance as the introduction and start to the finance major in the undergraduate business curriculum.
Association for investment management and research (AIMR) web site
Authors: Kahl Douglas
Published: September 2002

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From the Editor Vol 6 No 4
Authors: Lahey Karen Eilers
Published: September 2002

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An Analysis of the Tradeoff Between Tax Deferred Earnings in IRAs and Preferential Capital Gains
Authors: Crain Terry L. , Austin Jeffrey R.
Published: September 2002

This paper extends prior research in evaluating the decision of whether to invest in a mutualfund either outright or through one of the three available IRAs: the deductible IRA, the Roth IRA, and the nondeductible IRA. We provide mathematical models for after-tax accumulations for each of the investments that are a function of return, the percentage of the return currently taxable to the investor, the time horizon of the invest- ment, the capital gain tax rate, and the ordinary income tax rate. The Roth IRA and the deductible IRA always dominate investments in the nondeductible IRA or through out- right investment. However, in comparing the nondeductible IRA and outright investments, the outcome is dependent on the investment goals of the mutualfind and whether it generates substantial dividend distributions or capital gain distributions. Mutualfunds with small dividend and capital gain distributions may accumulate larger amounts if held outright while mutualfunds that pay substantial dividends or make sub- stantial capital gain distributions accumulate larger after-tax amounts when invested in a nondeductible IRA.
Risk Management and Insurance
Authors: Kahl Douglas
Published: September 2002

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Index Vol 6
Authors: Lahey Karen Eilers
Published: September 2002

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FACTORS AFFECTING EVER-MARRIED MEN’S CONTRACEPTIVE KNOWLEDGE AND USE IN NIGERIA
Authors: OYEDIRAN KOLAWOLE A. , ISHOLA GBENGA P. , FEYISETAN BAMIKALE J.
Published: September 2002

African men play important roles in the decisions about family life, including fertility and family planning. However, fertility and family planning research and programmes have ignored their roles in the past, focusing only on women’s behaviours. Since the 1994 International Conference on Population and Development (ICPD), interest in men’s involvement in reproductive health has increased. Unfortunately, data on their knowledge and use of contraception are generally scanty. This paper examines knowledge and use of contraception among ever-married men in Nigeria. A total of 1451 ever-married men aged 18–55 were interviewed in Imo and Ondo States, Nigeria. The findings reveal that men’s level of contraceptive knowledge is high in the study areas. About 90% knew at least one method of family planning. Furthermore, the level of contraceptive use among married men is such that men could participate in family planning activities if there were adequate programmes to involve them. Men in the sample areas were found not only to support their spouses’ use of contraceptives, but were actually using condoms to delay or prevent pregnancy. Age, education, place of residence, number of living children and being counselled for family planning were identified as key factors determining contraceptive knowledge and use among married men in the study areas. To ensure increased participation of men in family planning, programmes must be designed to educate them on the need for family size limitation and involve them in service delivery, even if only to their male counterparts.
Adjoint-based optimization of steady suction for disturbance control in incompressible flows
Authors: PRALITS JAN O. , HANIFI A. , HENNINGSON D. S.
Published: September 2002

The optimal distribution of steady suction needed to control the growth of single or
multiple disturbances in quasi-three-dimensional incompressible boundary layers on
a flat plate is investigated. The evolution of disturbances is analysed in the framework
of the parabolized stability equations (PSE). A gradient-based optimization procedure
is used and the gradients are evaluated using the adjoint of the parabolized stability
equations (APSE) and the adjoint of the boundary layer equations (ABLE). The
accuracy of the gradient is increased by introducing a stabilization procedure for the
PSE. Results show that a suction peak appears in the upstream part of the suction
region for optimal control of Tollmien–Schlichting (T–S) waves, steady streamwise
streaks in a two-dimensional boundary layer and oblique waves in a quasi-three-dimensional
boundary layer subject to an adverse pressure gradient. The mean flow
modifications due to suction are shown to have a stabilizing effect similar to that of
a favourable pressure gradient. It is also shown that the optimal suction distribution
for the disturbance of interest reduces the growth rate of other perturbations. Results
for control of a steady cross-flow mode in a three-dimensional boundary layer subject
to a favourable pressure gradient show that not even large amounts of suction can
completely stabilize the disturbance.
Faraday instability threshold in large-aspect-ratio containers
Authors: MANCEBO FRANCISCO J. , VEGA JOSÉ M.
Published: September 2002

We consider the Floquet linear problem giving the threshold acceleration for the
appearance of Faraday waves in large-aspect-ratio containers, without further restrictions
on the values of the parameters. We classify all distinguished limits for
varying values of the various parameters and simplify the exact problem in each limit.
The resulting simplified problems either admit closed-form solutions or are solved
numerically by the well-known method introduced by Kumar & Tuckerman (1994).
Some comparisons are made with (a) the numerical solution of the original exact
problem, (b) some ad hoc approximations in the literature, and (c) some
experimental results.
Inertial effects in time-dependent motion of thin films and drops
Authors: HOCKING L. M. , DAVIS S. H.
Published: September 2002

Capillarity is an important feature in controlling the spreading of liquid drops and
in the coating of substrates by liquid films. For thin films and small contact angles,
lubrication theory enables the analysis of the motion to be reduced to single evolution
equations for the heights of the drops or films, provided the inertia of the liquid can
be neglected. In general, the presence of inertia destroys the major simplification
provided by lubrication theory, but two special cases that can be treated are identified
here. In the first example, the approach of a drop to its equilibrium position is studied.
For sufficiently low Reynolds numbers, the rate of approach to the terminal state
and the contact angle are slightly reduced by inertia, but, above a critical Reynolds
number, the approach becomes oscillatory. In the latter case there is no simple relation
connecting the dynamic contact angle and contact-line speed. In the second example,
the spreading drop is supported by a plate that is forced to oscillate in its own plane.
For the parameter range considered, the mean spreading is unaffected by inertia, but
the oscillatory motion of the contact line is reduced in magnitude as inertia increases,
and the drop lags behind the plate motion. The oscillatory contact angle increases
with inertia, but is not in phase with the plate oscillation.
Neurotic symptoms, stress, or deprivation: which is most closely associated with incidence of suicide? An ecological study of English Health Authorities
Authors: BARTLETT C. J. , GUNNELL D. , HARRISON G. , MOORE L.
Published: September 2002

Background. Suicide rates, anxiety/depression scores and stress scores are routinely used as mental health indicators in populations, but their inter-relationships have not been explored. Our aim was to explore the association of suicide rates with anxiety/depression and stress scores, while also referring to deprivation scores, which are known to be linked to suicide rates.

Methods. We undertook an ecological analysis of English Health Authorities, regressing suicide rates (1993–1994), on General Health Questionnaire and stress scores (1994), and also on Jarman deprivation scores (1991).

Results. Overall, Jarman deprivation score was a better predictor of suicide rate than the psychological distress measures. There were no statistically significant associations between suicide rates and GHQ scores, although there was a weak association between suicide rate and mean stress level in women.

Conclusions. Suicide rates, though important in themselves, are not reliable indicators of the levels of neurotic symptoms or stress in populations. Suicide rates are more strongly associated with area-based measures of social disadvantage, though a possible stress–suicide relationship in women could be investigated further.
Control and controllability: beliefs and behaviour in high and low expressed emotion relatives
Authors: HOOLEY JILL M. , CAMPBELL CHRISTINE
Published: September 2002

Background. Expressed emotion (EE) is a measure of the family environment that is a well replicated psychosocial predictor of psychiatric relapse. Theoretical models of EE place heavy emphasis on the notion of control. We explored the extent to which high and low EE relatives made both attributions of control about patients and engaged in controlling behaviours.

Methods. Trained raters who were blind to information about EE coded interviews with 35 relatives of patients with schizophrenia and 42 relatives of patients with unipolar depression. Relatives were rated on two reliable scales that assessed relatives' tendencies to make illness controllability attributions and relatives' efforts to exert direct behavioural control over patients.

Results. In both the schizophrenia and depressed groups, high-EE relatives attributed more control to their ill family members than did low EE relatives. They also behaved in a more controlling manner. Examination of patients' clinical outcomes during a 9-month follow-up period revealed that high levels of behavioural control on the part of relatives significantly predicted relapse in patients with schizophrenia but not in patients with depression.

Conclusions. These findings support the attribution-based model of EE. They further suggest that controlling behaviours on the part of relatives may mediate the EE-relapse link in schizophrenia. Such behaviours may be important targets for modification in family-based interventions for schizophrenia.
Progression to AIDS, a clinical AIDS condition and mortality: psychosocial and physiological predictors
Authors: LESERMAN J. , PETITTO J. M. , GU H. , GAYNES B. N. , BARROSO J. , GOLDEN R. N. , PERKINS D. O. , FOLDS J. D. , EVANS D. L.
Published: September 2002

Background. The primary aim of this study is to examine prospectively the association of stressful life events, social support, depressive symptoms, anger, serum cortisol and lymphocyte subsets with changes in multiple measures of human immunodeficiency virus (HIV) disease progression.

Methods. Ninety-six HIV-infected gay men without symptoms or anti-retroviral medication use at baseline were studied every 6 months for up to 9 years. Disease progression was defined in three ways using the Centers for Disease Control (CDC) classifications (e.g. AIDS, clinical AIDS condition and mortality). Cox regression models with time-dependent covariates were used, adjusting for control variables (e.g. race, age, baseline, CD4 T cells and viral load, number of anti-retroviral medications).

Results. Higher cumulative average stressful life events and lower cumulative average social support predicted faster progression to both the CDC AIDS classification and a clinical AIDS condition. Higher anger scores and CD8 T cells were associated with faster progression to AIDS, and depressive symptoms were associated with faster development of an AIDS clinical condition. Higher levels of serum cortisol predicted all three measures of disease progression.

Conclusions. These results suggest that stressful life events, dysphoric mood and limited social support are associated with more rapid clinical progression in HIV infection, with serum cortisol also exerting an independent effect on disease progression.
Age–period–cohort effects on inequalities in psychological distress, 1981–2000
Authors: SACKER AMANDA , WIGGINS RICHARD D.
Published: September 2002

Background. In the closing decades of the twentieth century, changes in population sociodemographics took place that might be thought to have an adverse influence on the nation's psychological distress. Here, we examine the stability of social and gender inequalities in psychological distress throughout the 1980s and 1990s.

Methods. The study uses data from the 1958 National Child Development Study and the 1970 British Cohort Study collected when the cohort members were aged between 23 and 42. Multilevel logistic regression models were used to examine the effects of social class, gender, age, period and cohort on psychological distress as measured by the Malaise Inventory.

Results. We identify clear social inequalities in psychological distress during 1981–2000 that reduced in magnitude over this period. Non-linear age effects were observed: psychological distress improves in early adulthood but declines again on approaching mid-life. The 1970 cohort had poorer psychological distress than the 1958 cohort. Although women had higher rates of psychological distress than men, gender differences reduced in magnitude. Declining rates of women's psychological distress over time have not been matched in men. A reduction in social inequalities over time was also observed. Improvements in the psychological health of those in manual occupations were not equalled among those in non-manual occupations.

Conclusions. Both social and gender inequalities have narrowed in the last two decades of the twentieth century.
Dominance, diversity and distribution of lianas in Yasuní, Ecuador: who is on top?
Authors: Burnham Robyn J.
Published: September 2002

Lianas of Yasuní National Park and the Huaorani Ethnic Reserve, Ecuador were sampled using 0.2-ha subsamples from 12 1-ha plots. Using surveys and herbarium collections, the total species richness of lianas in the park and reserve is estimated to be close to 500 species. Terra firme habitats are significantly more species rich than floodplain habitats, but density of stems is not significantly different between habitats. The most abundant liana species is Machaerium cuspidatum Kuhlm. & Hoehne (Fabaceae) in both floodplain and terra firme habitats, representing more than 10% of all stems in census plots. Analysis of rarity indicates that none of the liana species encountered on the 12 plots is rare in terms of geographic range, and many species are not rare in terms of population size or habitat specificity. The rank order of abundance, combined with the coefficient of variability in species distribution among plots, is used to identify the 38
species (an oligarchy) that dominate forests in Yasuní.
Soundscape composition: the convergence of ethnography and acousmatic music
Authors: Levack Drever John
Published: September 2002

Despite roots in acoustic ecology and soundscape studies, the practice and study of soundscape composition is often grouped with, or has grown out of the acousmatic music tradition. This can be observed in the positioning of soundscape compositions juxtaposed with acousmatic music compositions in concert programmes, CD compilations and university syllabuses. Not only does this positioning inform how soundscape composition is listened to, but also how it is produced, sonically and philosophically. If the making and presenting of representations of environmental sound is of fundamental concern to the soundscape artist, then it must be addressed. As this methodological issue is outside of previous musical concerns, to this degree, we must look to other disciplines that are primarily engaged with the making of representation, and that have thoroughly questioned what it is to make and present representations in the world today. One such discipline is ethnography. After briefly charting the genesis of soundscape composition and its underlying principles and motivations, the rest of the paper will present and develop one perspective, that of considering soundscape composition as ethnography.
Responses of tropical rainforest birds to abandoned plantations, edges and logged forest in the Western Ghats, India
Authors: Shankar Raman T. R. , Sukumar R.
Published: September 2002

This study examined the effects of alteration of tropical rainforest vegetation structure and composition on bird community structure and the influence of life‐history traits on species persistence in the Kalakad‐Mundanthurai Tiger Reserve, Western Ghats. Systematic sampling for vegetation and point count surveys for birds were carried out in cardamom plantations abandoned for 5 and 15 years, plantation‐rainforest edges, a selectively logged forest patch and adjoining undisturbed rainforest sites. Principal components analysis of vegetation variables revealed clear differences between undisturbed and altered sites in woody plant and cane densities, canopy cover and vertical stratification. Bird species richness was lowest in cardamom plantations abandoned for 5 years and highest in logged and undisturbed forest. Bird species richness and similarity with undisturbed forest were significantly positively related to the vegetation component representing woody plant and cane (Calamus spp.) densities. Sites that were more similar in tree species composition had more similar bird communities whereas similarity in foliage profile between sites did not influence bird community similarity. Birds that were rare, were large‐bodied and belonged to the carnivore, omnivore, bark‐surface feeder and terrestrial insectivore guilds were adversely affected by habitat alteration. Restoring woody plant and cane densities and rainforest floristic composition in disturbed habitats may be required for management and conservation of bird communities typical to the region.
A theoretical analysis of competitive exclusion in a Trans‐Himalayan large‐herbivore assemblage
Authors: Mishra Chardutt , Van Wieren Sipke E. , Heitkönig Ignas M. A. , Prins Herbert H. T.
Published: September 2002

Understanding livestock grazing impacts on native wildlife is difficult when grazing is pervasive and has a long history. Spiti Valley in the Indian Trans‐Himalaya is characterized by overstocking of rangelands and a grazing history of over 3 millennia. An intriguing aspect of the wild large‐herbivore assemblage in Spiti Valley is its low diversity. In the present theoretical exploration, data on body masses of wild large‐herbivore species in the Trans‐Himalaya are examined against the backdrop of competition theory, to evaluate the possible role of competition in structuring the herbivore assemblage. The analysis is then expanded to include the livestock assemblage, and the possibility of the low wild herbivore diversity in Spiti Valley being a consequence of the high livestock diversity is explored. Null model analyses suggest that competitive interactions may have played a role in structuring the Trans‐Himalayan wild herbivore assemblage. This is reflected in a proportional regularity in species body masses, with each species, on average, being a constant proportion larger than the nearest smaller one. Such a proportional regularity is absent in the livestock assemblage. The analyses make a case for the competitive exclusion of at least four wild grazers in Spiti over the last 3 millennia. The present grazer assemblage conforms reasonably to the theoretical predictions ‐ these four species are among the six wild herbivores presently missing from Spiti. The implications of the analyses for conservation management in the Trans‐Himalaya are discussed.
Multiple mutagenesis of non-universal serine codons of the Candida rugosa LIP2 gene and biochemical characterization of purified recombinant LIP2 lipase overexpressed in Pichia pastoris
Authors: LEE Guan-Chiun , LEE Li-Chiun , SAVA Vasyl , SHAW Jei-Fu
Published: September 2002

The 17 non-universal serine codons (CTG) in the Candida rugosa LIP2 gene have been converted into universal serine codons (TCT) by overlap extension PCR-based multiple site-directed mutagenesis. An active recombinant LIP2 lipase was overexpressed in Pichia pastoris and secreted into the culture medium. The recombinant LIP2 showed distinguishing catalytic activities when compared with recombinant LIP4 and commercial C. rugosa lipase. The purified enzyme showed optimum activity at pH7 and a broad temperature optimum in the range 30–50°C. The enzyme retained 80% of residual activity after being heated at 70°C for 10min. Recombinant LIP2 demonstrated high esterase activity towards long-chain (C12–C16) p-nitrophenyl esters. Tributyrin was the preferred substrate among all triacylglycerols tested for lipolysis. Among cholesteryl esters, LIP2 showed highest lipolytic activity towards cholesteryl laurate. The esterification of myristic acid with alcohols of various chain lengths showed that the long-chain n-octadecanol (C18) was the preferred substrate. In contrast, the esterification of n-propanol with fatty acids of various chain lengths showed that the short-chain butyric acid was the best substrate. From comparative modelling analysis, it appears that several amino acid substitutions resulting in greater hydrophobicity in the substrate-binding site might play an important role in the substrate specificity of LIP2.
Molecular characterization of chicken syndecan-2 proteoglycan
Authors: CHEN Ligong , COUCHMAN John R. , SMITH Jacqueline , WOODS Anne
Published: September 2002

A partial syndecan-2 sequence (147bp) was obtained from chicken embryonic fibroblast poly(A)+ RNA by reverse transcription–PCR. This partial sequence was used to produce a 5′-end-labelled probe. A chicken liver cDNA library was screened with this probe, and overlapping clones were obtained encompassing the entire cDNA of 3kb. The open reading frame encodes a protein of 201 amino acids. The cytoplasmic domain is identical with that of mammalian syndecan-2, and highly similar to those of Xenopus laevis and zebrafish syndecan-2. The transmembrane domain is identical with that of mammalian and zebrafish syndecan-2, and highly similar to that of Xenopus laevis syndecan-2. The ectodomain is 45–62% identical with that of zebrafish, Xenopus laevis and mammalian syndecan-2. Two coding single nucleotide polymorphisms were observed. In vitro transcription and translation yielded a product of 30kDa. Western blotting of chicken embryonic fibroblast cell lysates with species-specific monoclonal antibody mAb 8.1 showed that chicken syndecan-2 is substituted with heparan sulphate, and that the major form of chicken syndecan-2 isolated from chicken fibroblasts is consistent with the formation of SDS-resistant dimers, which is common for syndecans. A 5′-end-labelled probe hybridized to two mRNA species in chicken embryonic fibroblasts, while Northern analysis with poly(A)+ RNAs from different tissues of chicken embryos showed wide and distinct distributions of chicken syndecan-2 during embryonic development. This pattern was different from that reported for syndecan-4, but consistent with the roles of syndecan-2 in neural maturation and in mesenchymal–matrix interactions.
Physical mechanisms behind the ion-cut in hydrogen implanted silicon
Authors: Höchbauer T. , Misra A. , Nastasi M. , Mayer J. W.
Published: September 2002

Hydrogen implanted silicon has been shown to cleave upon annealing, thus facilitating the transfer of thin silicon slices to other substrates, a process known as “ion-cut.” In our experiments 〈100〉 silicon wafers were implanted with 40 keV protons to a variety of ion doses ranging from 1×1016 to 1×1017 cm−2 and subsequently annealed at 600 °C. The samples were studied before and after annealing by a combination of Rutherford backscattering spectroscopy in channeling mode, elastic recoil detection analysis, atomic force microscopy, and electron microscopy. Mechanical stresses in the material, caused by proton irradiation, were determined by measuring changes in curvature of the silicon samples utilizing a laser scanning setup. For H doses of ⩾5×1016 cm−2 ion cutting in the form of “popping off” discrete blisters was obtained. Our analyses of the cleavage mechanisms had shown that the ion-cut location in silicon is largely controlled by the lattice damage that is generated by the H implantation process. At lower H doses, the location of the cut correlates well with the damage peak and can be explained by damage induced in-plane stress and the corresponding elastic out-of-plane strain. However, at higher implantation doses the ion-cut location shifts toward a deeper region, which contains lower damage and a sufficient concentration of H. This effect can be explained by a rapid decrease of the elastic out-of-plane strain coinciding with changing fracture mechanics at high H concentrations in heavily damaged silicon.
Characterization of GaN-based metal–semiconductor field-effect transistors by comparing electroluminescence, photoionization, and cathodoluminescence spectroscopies
Authors: Armani N. , Grillo V. , Salviati G. , Manfredi M. , Pavesi M. , Chini A. , Meneghesso G. , Zanoni E.
Published: September 2002

We report on a methodological comparison between photocurrent (PC), electroluminescence (EL), and cathodoluminescence (CL) investigations on GaN metal–semiconductor field-effect transistors. The purpose of this work is to show the effectiveness and the complementarity of these experimental techniques and to investigate the presence and nature of electron traps which limit the performances of the devices. PC measurements reveal four distinct energy levels, located at 1.75, 2.32, 2.67, and 3.15 eV, responsible for current collapse. The 1.75 eV level has also been observed in low temperature EL curves. The 2.32 and 2.67 eV levels, on the basis of the comparison with CL and EL results, can be correlated with the so-called “yellow band,” located at 2.2 eV. The origin of 1.75 and 3.15 eV levels is at present unknown, however a nonradiative nature has been attributed to the 3.15 eV level, due to the absence of this signature in both CL and EL spectra. The luminescence measurements also reveal the presence of the donor–acceptor pair emission at 3.27 eV and the near-band-edge transition at 3.45 eV. EL measurements show a series of emission peaks in the energy range between 1 and 1.4 eV, while the CL spectra reveal a broadband at 2.8 eV, which arises mainly from the semi-insulating layer. This result has been obtained by increasing the energy of the CL electron beam, allowing us to investigate both the conduction channel and the layers underneath it.
Thermodynamic and structural properties of a sticky hard-sphere heteronuclear dimer fluid
Authors: Wu Ning , Feng S. S. , Chiew Y. C.
Published: September 2002

The thermodynamic and structural properties of a sticky hard-sphere heteronuclear dimer fluid are studied using the multidensity Ornstein–Zernike integral equation theory. In this heteronuclear dimer fluid, each molecule consists of two sticky hard-sphere beads with identical diameters but interact with different strengths of stickiness. In this theoretical formalism, a monodisperse system of the heteronuclear sticky dimer is modeled as an equal molar binary mixture of associating sticky hard spheres (with different sticky strengths) in the complete association limit. A general analytical solution to the model was obtained within the Percus–Yevick and polymer Percus–Yevick approximations for any degree of association including the complete association limit. Explicit analytical expressions for the contact values of correlation functions are obtained. Furthermore, correlation functions beyond the hard-core region are calculated. The Helmholtz energy, Gibbs energy, and pressure of the heteronuclear dimer are obtained via the energy route. In addition, the critical temperature, critical density, and phase coexistence of the fluid are also computed.
Fragmentation of small tin cluster ions (Snx+: x=4–20) in the low-energy collisions with a highly oriented pyrolytic graphite surface
Authors: Tai Yutaka , Murakami Junichi , Majumder Chiranjib , Kumar Vijay , Mizuseki Hiroshi , Kawazoe Yoshiyuki
Published: September 2002

Fragmentation of tin cluster ions (Snx+: x=4–20) in the low-energy collisions with a HOPG surface has been investigated by means of a tandem time of flight mass spectrometer for the incident energy range of 0–300 eV. At low incident energies, smaller clusters (x⩽11) fragmented by the atom loss process, whereas larger clusters (x>11) decayed by fission. The favored fragmentation paths were similar to those for Si and Ge cluster ions. The results support the structural similarities among Si, Ge, and Sn clusters in the present size range. The low-energy fragmentation patterns were compared with those obtained from theoretical calculations using generalized gradient approximation (GGA) and the B3PW91 exchange–correlation functional. It has been found that the B3PW91 hybrid functional results are consistent with the experimental observations.
A partially incoherent rate theory of long-range charge transfer in deoxyribose nucleic acid
Authors: Zhang HouYu , Li Xin-Qi , Han Ping , Yu Xiang Yang , Yan YiJing
Published: September 2002

A quantum chemistry based Green’s function formulation of long-range charge transfer in deoxyribose nucleic acid (DNA) double helix is proposed. The theory takes into account the effects of DNA’s electronic structure and its incoherent interaction with aqueous surroundings. In the implementation, the electronic tight-binding parameters for unsolvated DNA molecules are determined at the HF/6-31G* level, while those for individual nucleobase–water couplings are at a semiempirical level by fitting with experimental redox potentials. Numerical results include that: (i) the oxidative charge initially at the donor guanine site does hop sequentially over all guanine sites; however, the revealed rates can be of a much weaker distance dependence than that described by the ordinary Ohm’s law; (ii) the aqueous surroundings-induced partial incoherences in thymine/adenine bridge bases lead them to deviate substantially from the superexchange regime; (iii) the time scale of the partially incoherent hole transport through the thymine/adenine π stack in DNA is about 5 ps.
Electron drift in C4F6 and C4F6/Ar mixtures
Authors: Goyette A. N. , Wang Yicheng , FitzPatrick G. J.
Published: September 2002

We report measurements of electron drift velocities as a function of density-reduced electric field, w(E/N), for hexafluorobutadiene (C4F6) and mixtures of C4F6 with Ar. The w(E/N) for the mixtures of C4F6 with Ar can aid Boltzmann transport equation analyses aimed at calculating cross-section sets for C4F6.
Photonic breakdown in up-conversion imaging devices based on the integration of quantum-well infrared photodetector and light-emitting diode
Authors: Ryzhii V. , Liu H. C.
Published: September 2002

We analyze the effect of photon recycling on up-conversion in a heterostructure device including a quantum well infrared photodetector (QWIP) integrated with a light emitting diode (LED). Such a QWIP-LED device converts middle infrared radiation into near infrared (NIR) or visible radiation (VIR) utilizing intersubband transitions in the QWIP and interband transitions in the LED. We show that the reabsorption of NIR/VIR photons in the QWIP can substantially affect the up-conversion of both uniform illuminations and infrared images. As demonstrated, this effect can cause a photonic breakdown associated with a positive feedback between the emission of NIR/VIR photons from the LED and the resulting photocurrent in the QWIP.
Enlargement of step-free SiC surfaces by homoepitaxial web growth of thin SiC cantilevers
Authors: Neudeck Philip G. , Powell J. Anthony , Beheim Glenn M. , Benavage Emye L. , Abel Phillip B. , Trunek Andrew J. , Spry David J. , Dudley Michael , Vetter William M.
Published: September 2002

Lateral homoepitaxial growth of thin cantilevers emanating from mesa patterns that were reactive ion etched into on-axis commercial SiC substrates prior to growth is reported. The thin cantilevers form after pure stepflow growth removes almost all atomic steps from the top surface of a mesa, after which additional adatoms collected by the large step-free surface migrate to the mesa sidewall where they rapidly incorporate into the crystal near the top of the mesa sidewall. The lateral propagation of the step-free cantilevered surface is significantly affected by pregrowth mesa shape and orientation, with the highest lateral expansion rates observed at the inside concave corners of V-shaped pregrowth mesas with arms lengthwise oriented along the 〈11̄00〉 direction. Complete spanning of the interiors of V’s and other mesa shapes with concave corners by webbed cantilevers was accomplished. Optical microscopy, synchrotron white beam x-ray topography and atomic force microscopy analysis of webbed regions formed over a micropipe and closed-core screw dislocations show that c-axis propagation of these defects is terminated by the webbing. Despite the nonoptimized process employed in this initial study, webbed surfaces as large as 1.4×10−3 cm2, more than four times the pregrowth mesa area, were grown. However, the largest webbed surfaces were not completely free of bilayer steps, due to unintentional growth of 3C-SiC that occurred in the nonoptimized process. Further process optimization should enable larger step-free webs to be realized.
Hydrophobic hydration and concentration fluctuations in aqueous solutions of urea derivatives. Evidence from dielectric and ultrasonic spectrometry
Authors: Kaatze Udo , Rupprecht Andreas
Published: September 2002

At 25 °C the complex (electric) permittivity of aqueous solutions of n-butylurea and tetramethylurea has been measured as a function of frequency ν (1 MHz ⩽ν⩽40 GHz) and solute concentration c 0.5 mol/l⩽c⩽1.26 mol/l). A suitable relaxation spectral function was fitted to the experimental data to yield various parameters, particularly the solute contribution to the static permittivity and the principal dielectric relaxation time of water. The former quantity has been evaluated to show equipartition of the structural isomers of n-BuU. The relaxation time is discussed in terms of local fluctuations in the solute concentration as deduced from ultrasonic spectra of the aqueous systems.