bluuebunny/crossref_metadata_2025 huggingface dataset:
Felsic (A-type)–basic (plume-induced) Early Palaeozoic
bimodal magmatism in the Maures
Massif (southeastern France)
Authors: BRIAND BERNARD , BOUCHARDON JEAN-LUC , CAPIEZ PAUL , PIBOULE MICHEL
Published: September 2002

The Maures Massif forms an important piece of the southernmost part of the Variscan belt
of western Europe. This massif exhibits high-grade bimodal felsic–basic volcanic complexes, a distinctive
lithological feature documented elsewhere in similar domains of the European Variscides and
referred to the Cambro-Ordovician extensional episode. Two major alkalic and tholeiitic compositional
groups and subordinate transitional metabasites have been identified, occurring at several distinct
horizons or in bimodal complexes. This chemical diversity is interpreted in terms of variable
degrees of partial melting of progressively depleted mantle source(s), which experienced melting at
different depths, from garnet to spinel stability domains, during a progressive mantle upwelling associated
with intracontinental rifting. This setting is reinforced by the presence of metabasites with compositions
similar to continental flood basalts, showing slightly humped REE patterns, and interpreted
as resulting from the melting of a partially depleted source at a relatively low degree of melting, in the
garnet–spinel transition zone. The metafelsites from the tholeiitic bimodal complex exhibit the distinctive
major and trace element characteristics of A-type rhyolites. Their elemental variations are consistent
with fractional crystallization of major and accessory phases, but some discontinuous REE
profiles result from a hydrothermal fractionation mechanism. The modelling of common anhydrous
fractionating assemblages suggests that these A-type compositions may be derived from the associated
tholeiites by extensive degrees of fractionation (90 %) with some continental crust involvement, or by
anhydrous partial melting (∼30 %) of an underplated mafic parent of tholeiitic composition. The
bimodal character of the Late Cambrian Maures magmatism, together with the chemistry of the various
metabasites and metafelsites, suggests plume-induced intracontinental magmatic activity, resulting
in lithospheric thinning prior to the onset of rifting and break-up of the Palaeozoic continental
lithosphere, at this northern margin of Gondwana.
Upper Cambrian trilobites and brachiopods from
Severnaya Zemlya, Arctic Russia, and their
implications for correlation and biogeography
Authors: RUSHTON A. W. A. , COCKS L. R. M. , FORTEY R. A.
Published: September 2002

A new Late Cambrian trilobite–brachiopod fauna from the Kurchavinskaya Formation,
Severnaya Zemlya, northern Siberia, allows correlation of the Ketyi Horizon of the NW Siberian succession
with the praecursor Zone of the Baltic olenid zonation. The presence on Severnaya Zemlya of
the typically Siberian trilobite Kujandaspis ketiensis indicates that even if Severnaya Zemlya lay on a
separate plate, whether Kara or Arctida as postulated by other authors, then it was still probably not
far from Siberia. However, the associated brachiopods are partly endemic to Severnaya Zemlya, thus
giving some support to the independent palaeomagnetic evidence for their origin on a plate separate
from Siberia.
Quaternary deformation of the Bajo Segura blind
fault (eastern Betic Cordillera, Spain) revealed by
high-resolution reflection profiling
Authors: ALFARO P. , ANDREU J. M. , ANDREU J. M. , ESTÉVEZ A. , SORIA J. M. , TEIXIDÓ T.
Published: September 2002

The blind reverse Bajo Segura Fault is located at the eastern extreme of the Trans-Alboran
shear zone (Betic Cordillera, southeast Iberian Peninsula). The surface expression of recent activity of
this blind ENE–WSW fault is represented by coseismic surface anticlines and growth synclines on
both sides of the anticlines. In the synclines, the deformation of the most recent Quaternary materials
is obscured by a sedimentary unit more than 30 m thick which was deposited during the later part of
the Late Pleistocene and the Holocene. The present study reports three high-resolution seismic profiles
made in the northern growth syncline, which was the one developed most by the Bajo Segura Fault. In
these seismic profiles we recognize the boundary between pre-growth strata and growth strata. This
marker, Early Pliocene in age, dates the start of the activity of this blind reverse fault. The geometry
observed in the seismic profiles of the syntectonic strata, dating from the Late Pliocene and
Quaternary, indicates a limb rotation folding mechanism. On seismic profile 2, the complex geometry
of the Benejúzar anticline forelimb can be attributed to several splay faults close to the surface of Bajo
Segura Fault.
REPRODUCTION IN HIGH ALTITUDE AYMARA: PHYSIOLOGICAL STRESS AND FERTILITY PLANNING?
Authors: CROGNIER E. , VILLENA M. , VARGAS E.
Published: September 2002

Reproductive characteristics at high altitude are described based on the reproductive histories of 720 Aymara women, collected in 1998 and 1999 in a group of twelve peasant communities at a mean altitude of 4000 m in the Bolivian Altiplano. The reproductive pattern is shaped by a late onset of childbearing, associated with a rather short reproductive span and large birth intervals. Environmental conditions could explain the particularly late age at menarche of rural girls compared with their urban counterparts, whereas the age at first birth is likely to be under cultural control. The short reproductive span appears to result from a large mean interval between last birth and menopause, which is essentially determined by cultural decisions. The birth intervals, which are longer than in many traditional societies, could be the result of a slower restoration of postpartum fecundability induced by the hard way of life inherent in the Altiplano (including poor sanitary and nutritional conditions and high workload), perhaps aggravated by hypoxia. However, a secular trend in fertility is perceptible, towards earlier menarche, earlier age at first birth, increasing reproductive span and a slight increase in live births and surviving offspring, which is probably the result of a slow improvement in living conditions. The existence of birth control on the one hand, and a total fertility rate averaging six live births among the couples who do not practise contraception on the other, are other arguments against the hypothesis of a low natural fecundity in these Aymara groups.
DEMOGRAPHIC AND HEALTH PATTERNS IN A RURAL COMMUNITY FROM THE BASQUE AREA IN SPAIN (1800–1990)
Authors: ALFONSO SÁNCHEZ MIGUEL A. , PANERA MENDIETA VICTORIA , PEÑA JOSÉ A. , CALDERÓN ROSARIO
Published: September 2002

In this work, the evolution of demographic and health patterns in a Basque rural population from Spain is analysed, as they relate to progress in demographic and epidemiological transition. For this purpose, parochial record data on 13,298 births and 9215 deaths, registered during the 19th and 20th centuries (1800–1990), were examined. The study area is a rural community called Lanciego, which is located at the southern end of the Rioja Alavesa area (Alava Province, Basque Country). In Lanciego, demographic transition began in the final decade of the 19th century, when a definite, irreversible trend began towards a reduction in mortality. The decrease in the birth rate came later than that in the death rate, and did not start until the 1930s. The post-transitional stage seemed to be reached in the 1970s, when the birth and death rates showed values below 20 per 1000. Other characteristics observed for the post-transitional stage in Lanciego are: (i) very low rates of infant mortality achieved at the expense of effective control of exogenous mortality; (ii) the mortality curve by ages changes from a U-shape (typical of populations with a high infant mortality rate and low life expectancy at birth) to a J-shape more characteristic of modern societies where longevity and life expectancy are considerably higher; (iii) a certain level of over-mortality among women in the senior age group (>65); and (iv) a significant proportion of mortality in recent times (1970–90) resulting from cardiovascular diseases and malignant neoplasms (post-transition causes). This last point is in contrast with observations from the first four decades of the 20th century, when infectious diseases and respiratory ailments were determining factors in mortality among this population. The data provided by the study of the variation over time in demographic and health patterns indicate that reducing the risk of mortality is one of the most important preconditions for fertility decline.
Drift instability of standing Faraday waves
Authors: MARTÍN ELENA , MARTEL CARLOS , VEGA JOSÉ M.
Published: September 2002

We consider the weakly nonlinear evolution of the Faraday waves produced in a
vertically vibrated two-dimensional liquid layer, at small viscosity. It is seen that the
surface wave evolves to a drifting standing wave, namely a wave that is standing in a
moving reference frame. This wave is determined up to a spatial phase, whose calculation
requires consideration of the associated mean flow. This is just the streaming
flow generated in the boundary layer attached to the lower plate supporting the liquid.
A system of equations is derived for the coupled slow evolution of the spatial phase
and the streaming flow. These equations are numerically integrated to show that the
simplest reflection symmetric steady state (the usual array of counter-rotating eddies
below the surface wave) becomes unstable for realistic values of the parameters. The
new states include limit cycles (the array of eddies oscillating laterally), drifted standing
waves (patterns that are standing in a uniformly propagating reference frame)
and some more complex attractors.
A weakly nonlinear model of long internal waves in closed basins
Authors: HORN D. A. , IMBERGER J. , IVEY G. N. , REDEKOPP L. G.
Published: September 2002

A simple model is developed, based on an approximation of the Boussinesq equation,
that considers the weakly nonlinear evolution of an initial interface disturbance in a
closed basin. The solution consists of the sum of the solutions of two independent
Korteweg–de Vries (KdV) equations (one along each characteristic) and a second-order
wave–wave interaction term. It is demonstrated that the solutions of the two
independent KdV equations over the basin length [0, L] can be obtained by the
integration of a single KdV equation over the extended reflected domain [0, 2L]. The
main effect of the second-order correction is to introduce a phase shift to the sum of
the KdV solutions where they overlap. The results of model simulations are shown to
compare qualitatively well with laboratory experiments. It is shown that, provided the
damping timescale is slower than the steepening timescale, any initial displacement
of the interface in a closed basin will generate three types of internal waves: a packet
of solitary waves, a dispersive long wave and a train of dispersive oscillatory waves.
An oscillatory secondary bifurcation for magnetoconvection and rotating convection at small aspect ratio
Authors: HALFORD A. R. , PROCTOR M. R. E.
Published: September 2002

We consider the dynamics of convection in a strong vertical magnetic field, and in the
presence of rapid rotation. In both these cases, in circumstances which can be realized
in the laboratory, the onset of convection is in the form of tall thin cells. Because of
this, the dynamics near onset is characterized by an interaction between the cellular
modes and the horizontally averaged temperature profile. The effects on the dynamics
are slight in the case of a Boussinesq fluid. However in both cases, when the layer
is stratified (non-Boussinesq), the convection can lose stability to oscillations close to
onset. Properties of the oscillations and their stability to long-wavelength modulation
are extensively investigated.
Energy dissipation in body-forced turbulence
Authors: DOERING CHARLES R. , FOIAS CIPRIAN
Published: September 2002

Bounds on the bulk rate of energy dissipation in body-force-driven steady-state
turbulence are derived directly from the incompressible Navier–Stokes equations. We
consider flows in three spatial dimensions in the absence of boundaries and derive
rigorous a priori estimates for the time-averaged energy dissipation rate per unit mass,
ε, without making any further assumptions on the flows or turbulent fluctuations. We
prove

ε [les ] c1vU2/l2
+ c2U3/l,

where v is the kinematic viscosity, U is the root-mean-square (space and time averaged)
velocity, and l is the longest length scale in the applied forcing function. The prefactors
c1 and c2 depend only on the functional shape of the body force and
not on its magnitude or any other length scales in the force, the domain or the flow. We also
derive a new lower bound on ε in terms of the magnitude of the driving force F. For
large Grashof number Gr = Fl3/v2, we find

c3vFl/λ2 [les ] ε

where λ = √vU2/ε is the Taylor microscale in the flow and the
coefficient c3 depends only on the shape of the body force. This estimate is seen to be
sharp for particular forcing functions producing steady flows with λ/l ∼ O(1)
as Gr → 1. We interpret both the upper and lower bounds on ε in terms of the conventional
scaling theory of turbulence – where they are seen to be saturated – and discuss them in the
context of experiments and direct numerical simulations.
Viscous interactions of two co-rotating vortices before merging
Authors: LE DIZÈS STÉPHANE , VERGA ALBERTO
Published: September 2002

The viscous evolution of two co-rotating vortices is analysed using direct two-dimensional
numerical simulations of the Navier–Stokes equations. The article focuses
on vortex interaction regimes before merging. Two parameters are varied: a steepness
parameter n which measures the steepness of the initial vorticity profiles in a given
family of profiles, and the Reynolds number Re (between 500 and 16 000). Two distinct
relaxation processes are identified. The first one is non-viscous and corresponds
to a rapid adaptation of each vortex to the external (strain) field generated by the
other vortex. This adaptation process, which is profile dependent, is described and explained
using the damped Kelvin modes of each vortex. The second relaxation process
is a slow diffusion phenomenon. It is similar to the relaxation of any non-Gaussian
axisymmetrical vortex towards the Gaussian. The quasi-stationary solution evolves
on a viscous-time scale toward a single attractive solution which corresponds to the
evolution from two initially Gaussian vortices. The attractive solution is analysed in
detail up to the merging threshold a/b ≈ 0.22 where a and b are the vortex radius
and the separation distance respectively. The vortex core deformations are quantified
and compared to those induced by a single vortex in a rotating strain field. A good
agreement with the asymptotic predictions is demonstrated for the eccentricity of
vortex core streamlines. A weak anomalous Reynolds number dependence of the
solution is also identified. This dependence is attributed to the advection–diffusion
of vorticity towards the hyperbolic points of the system and across the separatrix
connecting these points. A Re1/3 scaling for the vorticity at the central hyperbolic
point is obtained. These findings are discussed in the context of a vortex merging
criterion.
Anxiety disorders and the onset of depression among adults in the community
Authors: GOODWIN RENEE D.
Published: September 2002

Objective. To determine the association between anxiety disorders, panic attack and the risk of major depression among adults in the community.

Method. Data were drawn from the Epidemiologic Catchment Area Program survey waves 1 (N = 20291) and 2 (N = 15849). Multivariate logistic regression analyses were used to determine the risk of incident major depression at 12-month follow-up (wave 2) associated with each anxiety disorder and panic attacks assessed at wave 1, adjusting for differences in sociodemographic characteristics, and then controlling simultaneously for all anxiety disorders, and other psychiatric co-morbidity.

Results. Specific phobia (OR = 1.7 (1.6, 1.8)), agoraphobia (OR = 2.3 (2.2, 2.5)), obsessive–compulsive disorder (OR = 5.4 (5.0, 5.8)) and panic attack (OR = 1.9 (1.8, 2.1)) each made an independent contribution to the risk of major depression, which persisted after adjusting simultaneously for sociodemographic differences and other psychiatric co-morbidity.

Conclusions. Each anxiety disorder and panic attacks appear to confer an independent risk for the onset of major depression within 12-months among adults in the community. Understanding the key role played by anxiety in depression onset is needed for prevention strategies.
Parental bonding and adult psychopathology: results from the US National Comorbidity Survey
Authors: ENNS M. W. , COX B. J. , CLARA I.
Published: September 2002

Background. Research using the parental bonding instrument (PBI) has suggested that lack of parental care and/or overprotection may be important risk factors for adult mental disorders. Much of this research, however, has relied on clinical populations with one or two disorders, or has used highly select community samples.

Method. The association between parenting experiences and the occurrence of 13 common mental disorders in adulthood was evaluated in the US National Comorbidity Survey (N = 5877). The effect of sociodemographic variables (age, education, income) was statistically controlled and the effects of six parenting variables (maternal and paternal care, overprotection and authoritarianism) were examined simultaneously. The effects in men and women were examined separately.

Results. Lack of care was the parenting variable most consistently associated with adult psychopathology. Parenting experiences with one's mother were more consistently associated with adult mental disorders. In general the impact of parenting was diagnostically non-specific. However, there appeared to be some unique effects for externalizing disorders (substance use disorders and antisocial personality disorder) in males; paternal overprotection and authoritarianism conferred a reduced risk of externalizing disorders in adult males. The overall impact of parenting as assessed by the PBI was modest, accounting for about 1 to 5% of the variance in the occurrence of adult mental disorders.

Conclusion. Parenting experiences, particularly lack of care, are potentially causally related in a non-specific manner to a wide variety of forms of adult psychopathology in both men and women. The overall magnitude of the effect is small but statistically significant in a nationally representative US sample.
Back–neck pain and symptoms of anxiety and depression: a population-based twin study
Authors: REICHBORN-KJENNERUD T. , STOLTENBERG C. , TAMBS K. , ROYSAMB E. , KRINGLEN E. , TORGERSEN S. , HARRIS J. R.
Published: September 2002

Background. Clinical and epidemiological studies have shown an association between anxiety and depression and pain in the back and neck. The nature of this relationship is not clear. This study aimed to investigate the extent to which common genetic and environmental aetiological factors contribute to the covariance between symptoms of anxiety and depression and back–neck pain.

Methods. Measures of back–neck pain and symptoms of anxiety and depression were part of a self-report questionnaire sent in 1992 to twins born in Norway between 1967 and 1974 (3996 pairs). Structural equation modelling was applied to determine to what extent back–neck pain and symptoms of anxiety and depression share genetic and environmental liability factors.

Results. The phenotypic correlation between symptoms of anxiety and depression and back–neck pain was 0.31. Individual differences in both anxiety and depression and back–neck pain were best accounted for by additive genetic and individual environmental factors. Heritability estimates were 0.53 and 0.30 respectively. For back–neck pain, however, a model specifying only shared- and individual environmental effects could not be rejected. Bivariate analyses revealed that the correlation between back–neck pain and symptoms of anxiety and depression was best explained by additive genetic and individual environmental factors. Genetic factors affecting both phenotypes accounted for 60% of the covariation. There were no significant sex differences.

Conclusion. The results support previous findings of a moderate association between back–neck pain and symptoms of anxiety and depression, and suggest that this association is primarily due to common genetic effects.
Prevention and treatment of post-partum depression: a controlled randomized study on women at risk
Authors: CHABROL, H. , TEISSEDRE, F. , SAINT-JEAN, M. , TEISSEYRE, N. , ROGÉ B. , MULLET E.
Published: September 2002

Background. Research is needed to evaluate the efficacy of prevention and treatment for post-partum depression.

Method. Subjects were screened with the Edinburgh Post-natal Depression Scale (EPDS) at the obstetric clinic. Mothers at risk (N = 258) (EPDS scores [ges ]9) were randomly assigned to a prevention/treatment group or a control group. The prevention group received one cognitive-behavioural prevention session during hospitalization. At 4 to 6 weeks post-partum, subjects were screened again with the EPDS, after drop-out rates (refusals plus no return of the second EPDS) of 25.4% (33/130) in the intervention group and 10.9% (14/128) in the control group. Mothers with probable depression (EPDS scores [ges ]11) were assessed using the Hamilton Depression Rating Scale (HDRS) and the Beck Depression Inventory (BDI). Mothers with major depression continued in the treatment group (N = 18) or in the control group (N = 30). Treated subjects received a cognitive-behavioural programme of between five and eight weekly home-visits.

Results. Compared with the control group, women in the prevention group had significant reductions in the frequency of probable depression (30.2% v. 48.2%). Recovery rates based on HDRS scores of <7 and BDI scores of <4 were also significantly greater in the treated group than in the control group.

Conclusions. The study suggests that this programme for prevention and treatment of post-partum depression is reasonably well-accepted and efficacious.
Tree species distribution and community structure of central
Amazonian várzea forests by remote-sensing techniques
Authors: Wittmann Florian , Anhuf Dieter , Funk Wolfgang J.
Published: September 2002

In central Amazonian white-water floodplains (várzea), different forest types become established in relation to the flood-level gradient. The formations are characterized by typical patterns of species composition, and their architecture results in different light reflectance patterns, which can be detected by Landsat TM image data. Ground checking comprised a detailed forest inventory of 4 ha, with Digital Elevation Models (DEM) being generated for all sites. The results indicate that, at the average flood level of 3 m, species diversity and architecture of the forests changes, thus justifying the classification into the categories of low várzea (várzea baixa) and high várzea (várzea alta). In a first step to scale up, the study sites were observed by aerial photography. Tree heights, crown sizes, the projected crown area coverage and the gap frequencies provide information, which confirms a remotely sensed classification into three different forest types. The structure of low várzea depends on the successional stage, and species diversity increases with increasing age of the formations. In high várzea, only one successional stage was found and species diversity is higher than in all low-várzea formations. The more complex architecture of the high-várzea forest results in a more diffuse behaviour pattern in pixel distribution, when scanned by TM image data.
Links between terrain characteristics and forage patterns of elephants (Loxodonta africana) in northern Botswana
Authors: Nellemann Christian , Moe Stein R. , Rutina Lucas P.
Published: September 2002

Spatial vegetation utilization of elephants was investigated within mixed woodland savanna along the Chobe River in northern Botswana in the dry season of 1998. Using multiple linear regression, accumulated stem breakage by elephants was predicted by a terrain index, distance to water, stand density, number of trees > 4 m tall, tree height, density of Combretum apiculatum, C. elaeagnoides, C. mossambicense and the density of other (accumulated) tree species. Within mixed woodland at 2–7 km distance from the river fine-grained terrain ruggedness was the most important factor contributing to 55% of observed differences in use by elephants, while distance to water and the density of C. apiculatum contributed an additional 20% and 4%, respectively to the multiple linear regression model. Stem breakage was, on average, almost twice as high in rugged terrain compared with flat terrain at similar distance to water within the same vegetation type. Rugged terrain had 2–3-fold higher proportion of plots with very high Combretum shrub densities. These results suggest that the terrain index may be useful in management, predicting the areas most sensitive to vegetation change in a woodland system with increasing elephant densities.
Attributing Mozart (i): three accompanied recitatives
Authors: EDGE DEXTER
Published: September 2002

In a recent issue of the Cambridge Opera Journal, Dorothea Link has proposed that Mozart may have been the author of an unattributed accompanied recitative that precedes the aria ‘‘Vado, ma dove?,” K. 583, in the Viennese court theatre’s original performing score of Martín y Soler's Il burbero di buon cuore. The present article re-examines the case for Mozart's authorship of this recitative in the wider context of Mozart studies as a whole, and through a detailed reconsideration of the source and stylistic evidence. The recitative preceding K. 583 is compared to two other accompanied recitatives with plausible connections to Mozart: an unattributed one that precedes a score of Mozart's aria ‘‘No, che non sei capace,” K. 419, in a Viennese manuscript of extracts from Paisiello’s Fedra; and one that is explicitly attributed to Mozart in the Viennese court theatre's original performing score of a pasticcio based on Guglielmi's La quacquera spirituosa.
Circumscribed journeys through soundscape composition
Authors: McCartney Andra
Published: September 2002

The soundscape composition is the journey that circumscribes the relationship,
the conversation between composer and sound sources. (Hildegard Westerkamp)

Environmental sounds hold an unusual place in our imaginations. On the one hand,
hey make up the often unnoticed ambiences of our daily lives: they are so much with us and
surrounding us that it takes a special effort to bring them into the foreground,
and pay attention to them. On the other hand, environmental sounds form a powerful conduit to memory. Hearing a particular sound or ambience can launch a chain of related memories, whether experienced consciously or working subconsciously, that reconnects us with particular places and times in our lives. It is precisely these confluences of memory, time and place that interest those who compose with soundscapes.
Sound and sign
Authors: Proy Gabriele
Published: September 2002

In discussing different sound environments - sound in the field of art as well as sound in the context of our daily sonic environment - this article makes reference to semiotic theories.

Sound without source. Electroacoustic media shape our perceptive realities. There are multiple tools available to record and reproduce sound, but is it possible to handle the fleeting nature of sound, the escape of sound? Certainly there are tools to manipulate sound, to create new soundscapes in this way. We can generate virtual
sound-projecting soundscapes via speakers, via headphones in a new context - but what are we listening to?

Every sound evokes images. The concept of ‘musique acousmatique’, according to François Bayle, amplifies Pierre Schaeffer's notion of the ‘objet sonore’. ‘Musique acousmatique’ refers to sound projection, and thus to our imagination while concentrating on listening. In listening to acousmatic music, we can find three tonal levels, and this tripartite concept of listening refers to the tripartite semiotic concept introduced by Charles Sanders Peirce.

Finally, sound affects us emotionally. In contradiction to the term ‘objet sonore’, the term ‘sound event’ coined by R. Murray Schafer stresses the necessity to analyse sound in its context. It is the sonic environment which determines the meaning of the ‘sound event’. Thus, from my point of view, the concept of soundscape can be compared with Ferdinand de Saussure's semiotic theory about the arbitrary meaning of signs. Signs are determined by their systems.

Semiotic concepts offer an interesting approach to sound perception. Let's listen to soundscapes before sound escapes.
Hildegard Westerkamp's Kits Beach Soundwalk: shifting perspectives in real world music
Authors: Kolber David
Published: September 2002

Hildegard Westerkamp's Kits Beach Soundwalk challenges us as listeners to re-evaluate our acoustic soundscape. Juxtaposing the sounds of barnacles with the noise of the city, Westerkamp reveals an unbalanced world in which individual voices are silenced. Kits Beach Soundwalk allows Westerkamp to help rectify that imbalance. It provides her with the opportunity to create a place in which a listener can take pleasure in simply being. She reveals the metaphors, the hidden entrances, within sounds that take us into other spaces. A listener travels with Westerkamp into worlds of tiny sounds and tiny voices, dreams, and places of fantasy and the imagination. She challenges us as listeners to re-establish our place within the world around us. By designing the piece to reach the audience on a number of levels - intellectual, physiological, metaphorical - Westerkamp effectively promotes the changing of listening habits; the distancing of individuals from oppressive sonic environments; and the regaining of an individual's inner voice.
Empirical estimates of minimum viable population sizes for primates: tens to tens of thousands?
Authors: Harcourt A.H.
Published: September 2002

Theoretical estimates of long‐term minimum viable population (MVP) sizes for mammals indicate MVPs of tens of thousands, even a million. However, data to test the theoretical estimates are effectively non‐existent. I here use information on distributions of primates on islands of southeast Asia to provide empirical estimates of the size of multi‐millennial MVPs following the post‐Pleistocene insularization in the Sunda region. Small Sunda region islands have fewer taxa than do large ones. Assuming extinction on the small islands, the MVP size is somewhere between the population size on the smallest island on which the taxon is extant and that on the largest island on which the taxon no longer exists (population size calculated as density of taxon by area of land available). Results for eight to ten genera (depending on the taxonomy) on 35 islands indicate MVPs of perhaps a few score for Nycticebus (loris) and Macaca (macaque) to several thousands, or scores of thousands, for Pongo (orang‐utan) and Symphalangus (siamang). Large‐bodied taxa have significantly larger MVPs than do small‐bodied taxa. Only four protected areas in southeast Asia are large enough to conserve the smaller MVPs of the siamang and orang‐utan.
Inhibition of cholesterol biosynthesis by Δ22-unsaturated phytosterols via competitive inhibition of sterol Δ24-reductase in mammalian cells
Authors: FERNÁNDEZ Carlos , SUÁREZ Yajaira , FERRUELO Antonio J. , GÓMEZ-CORONADO Diego , LASUNCIÓN Miguel A.
Published: September 2002

Dietary phytosterols are cholesterol-lowering agents that interfere with the intestinal absorption of cholesterol. In the present study, we have studied their effects on cholesterol biosynthesis in human cells, particularly in the sterol-conversion pathway. For this, both Caco-2 (intestinal mucosa) and HL-60 (promyelocytic) human cell lines were incubated with [14C]acetate, and the incorporation of radioactivity into sterols was determined using HPLC and radioactivity detection online. Sterols containing a double bond at C-22 in the side chain (stigmasterol, brassicasterol and ergosterol) dramatically inhibited the activity of sterol Δ24-reductase, as indicated by the decrease in radioactivity incorporation into cholesterol and the accumulation of its precursors (mainly desmosterol). Phytosterols with the saturated side chain (β-sitosterol and campesterol) were inactive in this regard. The inhibition of sterol 24-reductase was confirmed in rat liver microsomes by using 14C-labelled desmosterol as the substrate. The 22-unsaturated phytosterols acted as competitive inhibitors of sterol 24-reductase, with Ki values (41.1, 42.7 and 36.8μM for stigmasterol, brassicasterol and ergosterol respectively) similar to the estimated Km for desmosterol (26.3μM). The sterol 5,22-cholestedien-3β-ol, an unusual desmosterol isomer that lacks the alkyl groups characteristic of phytosterols, acted as a much stronger inhibitor of 24-reductase (Ki = 3.34μM). The usually low intracellular concentrations of the physiological substrates of 24-reductase explains the strong inhibition of cholesterol biosynthesis that these compounds exert in cells. Given that inhibition of sterol 24-reductase was achieved at physiologically relevant concentrations, it may represent an additional mechanism for the cholesterol-lowering action of phytosterols, and opens up the possibility of using certain 22-unsaturated sterols as effective hypocholesterolaemic agents.
Statistical mechanical refinement of protein structure prediction schemes: Cumulant expansion approach
Authors: Eastwood Michael P. , Hardin Corey , Luthey-Schulten Zaida , Wolynes Peter G.
Published: September 2002

We discuss how protein structure prediction schemes may be refined via a cumulant expansion approach using optimization criteria motivated by energy landscape ideas. The approach is advantageously combined with a free energy profile analysis based on multiple histogram sampling methods, which enables a quantitative assessment of the effects of refinement on the energy landscape to be made. The approach is widely applicable, but is illustrated here for a previously described prediction scheme intended for use in the absence of any known homology information. The relationship to previous optimization schemes is discussed.
Vibrational emissions of CO213 trapped in rare gas matrices: Kinetic model for the intramolecular relaxation
Authors: Chabbi H. , Gauthier-Roy B. , Vasserot A.-M. , Abouaf-Marguin L.
Published: September 2002

The ν3 vibrational mode of CO213, trapped in a rare gas matrix, is excited by a laser pulse near 2300 cm−1. Emission is then observed in the 16 μm region and assigned to three transitions: namely, 3ν21-2ν20, 3ν21-2ν22, and 2ν20-ν21, which are all observed in neon and for the two sites in argon. 3ν21-2ν22 is missing in krypton. In xenon the emission, much weaker and longer (ms range), cannot be frequency resolved and behaves like spontaneous emission. In the other cases, all the recorded signals exhibit the characteristics of vibrational stimulated emission (VSE). The temporal profile of VSE is different for the three transitions and highly depends on the matrix material (1–100 μs). The relative intensities of the different VSE transitions depend on the matrix and on the energy of the exciting pulse. These results are interpreted using a kinetic model which takes into account absorption, spontaneous and stimulated emission, and nonradiative transfers between the involved vibrational levels. The model provides numerical simulations of the emissions, which are adjusted to experimental features (time behavior and relative intensities). Orders of magnitude values are thus extracted for the transfer rates and compared to literature values.
Secrecy capacity in the four-state protocol of quantum key distribution
Authors: Brandt Howard E.
Published: September 2002

The process of key distillation from the quantum transmission in quantum key distribution is reviewed, with the objective of calculating the secrecy capacity of the four-state protocol in the presence of an individual attack in which the eavesdropping probe is entangled with the signal states, and states of the probe become correlated with the states measured by the legitimate receiver. Emphasis is placed on information leakage to the eavesdropping probe. The calculation generalizes earlier work to include an arbitrary angle between the signal bases.
Hiding messages in quantum data
Authors: Gea-Banacloche Julio
Published: September 2002

A method is proposed to hide messages in arbitrary quantum data files. The messages may act as “watermarks,” to secure the authenticity and/or integrity of the data. With the help of classical secret keys, they can be made unreadable by other parties and to reveal whether thay have been tampered with. The basic idea is to encode the data using a quantum error-correcting code and hide the message as (correctible) errors, deliberately inserted, which can be read out from the error syndrome. Also discussed briefly is a “reverse encoding,” which would involve putting the actual data in the error syndrome, and letting the encoded qubit itself carry the message.
Detailed study of the composition of hydrogenated SiNx layers for high-quality silicon surface passivation
Authors: Mäckel H. , Lüdemann R.
Published: September 2002

We have analyzed the role of the bond densities of a-SiNx:H films on the passivation properties at the SiNx:H/Si interface. The films are deposited onto silicon wafers by plasma enhanced chemical vapor deposition using a 13.56 MHz direct plasma system and a SiH4/N2/H2 gas mixture. Fourier transform infrared spectroscopy measurements are performed in order to obtain the bonding concentration of Si–Si, Si–H, Si–N and N–H. The passivation properties are deduced by lifetime measurements using a microwave-detected photoconductance decay technique. Carrier lifetimes of the SiNx:H-passivated silicon wafers of up to 1200 μs correlate to surface recombination velocities, Seff, as low as 4–6 cm/s. This means that the films provide excellent passivation of silicon surfaces, which is necessary for high-efficiency solar cells. The Si–H bond density and the total bond density are considered as measures of the passivation quality. Models for the formation of K+ centers and for the passivation pathways during the plasma deposition are proposed. The addition of a further hydrogen source to the plasma gas (H2) leads to a better defect passivation of Si dangling bonds during the deposition.
Evaluation of the annealing effect of proton-exchanged LiTaO3 optical waveguides by the line-focus-beam ultrasonic material characterization system
Authors: Miyashita Masahito , Kushibiki Jun-ichi
Published: September 2002

We established an experimental procedure and collected basic data to evaluate the annealing process and effects for proton-exchanged LiTaO3 optical waveguides using the line-focus-beam ultrasonic material characterization (LFB-UMC) system in a frequency range of 100 to 300 MHz. Twelve Z-cut LiTaO3 substrates were proton-exchanged at 260 °C for 14 min in a pyrophosphoric acid solution and annealed at 420 °C for various periods from 10 sec to 24 h. The leaky surface acoustic wave (LSAW) velocities were decreased by the proton exchange, and were then increased and recovered by annealing in all propagation directions as the annealing time increased. The Y-axis propagation is most useful for an evaluation. The LSAW velocities decrease with an increase of the product fH, obtained from the frequency dependences and proton-diffused layer depths analyzed by secondary-ion mass spectrometry. Gradients of the fH dependences of the LSAW velocities become gentler with increases in the annealing time, corresponding to the concentrations and distributions of hydrogen and lithium ions in the proton-diffused layers. The relationships among the LSAW velocities, proton-diffused layer depths, relative concentrations of hydrogen ions at the specimen surfaces, and the annealing times were experimentally obtained. The measurement resolutions of the LFB-UMC system at 225 MHz to the proton-diffused layer depth, the relative concentration of hydrogen ions, and the typical annealing time for 1 min were estimated to be 4 nm, 0.2%, and 0.6 sec.
Electron irradiation induced phase decomposition in alkaline earth multi-component oxide glass
Authors: Jiang Nan , Silcox John
Published: September 2002

Electron irradiation induced phase decomposition in an alkaline earth multi-component oxide glass has been observed in a scanning transmission electron microscope. Separate regions that are rich and poor in alkaline earths form rapidly during the initial irradiation. In other words, alkaline earth multi-component oxide glasses are intolerant of high-energy (∼100 kV) electrons. This could result from the characteristics of a nonbridging O atom that bound to both Si (covalent) and alkaline earths (ionic). A modified Knotek–Feibelman model has been introduced to interpret the breakaway of cations from the glass network. Driven by electrostatic forces, the cations prefer to segregate, forming a cation rich region to reduce the amount of nonbridging O.
Dynamics of glass-forming liquids. VI. Dielectric relaxation study of neat decahydro-naphthalene
Authors: Duvvuri Kalyan , Richert Ranko
Published: September 2002

We have measured the dielectric relaxation of neat cis/trans-decahydro-naphthalene (decalin) in its supercooled regime as a function of temperature. The fragility of this nonaromatic molecular glass former is extremely high, m=147, and the distribution of relaxation times in terms of the stretching exponent is accordingly wide, β≈0.33. Regarding molecular organic liquids, such high fragilities have been observed before only for aromatic systems, e.g., toluene and triphenyl-phosphite. It turns out that the structural relaxation of neat decaline differs significantly from that of the 17.2 mol % chlorobenzene doped counterpart reported earlier.
Vibrational relaxation in clusters: Energy transfer in I2−(CO2)4 excited by femtosecond stimulated emission pumping
Authors: Davis Alison V. , Wester Roland , Bragg Arthur E. , Neumark Daniel M.
Published: September 2002

Vibrational relaxation dynamics in I2−(CO2)4 clusters are monitored by femtosecond stimulated emission pumping in conjunction with femtosecond photoelectron spectroscopy. Femtosecond pump and tunable dump pulses coherently excite the I2− within the cluster with vibrational energies ranging from 0.57 to 0.86 eV; the subsequent dynamics are monitored via the time-dependent photoelectron spectrum, and are compared to those resulting from excitation of bare I2−. Two observables are used to follow the vibrational relaxation from the vibrationally excited I2− to the surrounding solvent molecules. From 0 to 4 ps, relaxation is apparent through a time-dependent increase in the oscillation which is monitored at its inner turning point. At longer times, out to ∼100 ps, shifts in the photoelectron spectra are used to determine the vibrational energy content of the I2−. Indirect evidence is presented for early rapid energy loss during the first half-oscillation of the wave packet across the potential.
Nanomechanical displacement sensing using a quantum point contact
Authors: Cleland A. N. , Aldridge J. S. , Driscoll D. C. , Gossard A. C.
Published: September 2002

We describe a radio frequency mechanical resonator that includes a quantum point contact, defined using electrostatic top gates. We can mechanically actuate the resonator using either electrostatic or magnetomotive forces. We demonstrate the use of the quantum point contact as a displacement sensor, operating as a radio frequency mixer at the mechanical resonance frequency of 1.5 MHz. We calculate a displacement sensitivity of about 3×10−12 m/Hz1/2. This device will potentially permit quantum-limited displacement sensing of nanometer-scale resonators, allowing the quantum entanglement of the electronic and mechanical degrees of freedom of a nanoscale system.
Analytical model for the optical functions of amorphous semiconductors from the near-infrared to ultraviolet: Applications in thin film photovoltaics
Authors: Ferlauto A. S. , Ferreira G. M. , Pearce J. M. , Wronski C. R. , Collins R. W. , Deng Xunming , Ganguly Gautam
Published: September 2002

We have developed a Kramers–Kronig consistent analytical expression to fit the measured optical functions of hydrogenated amorphous silicon (a-Si:H) based alloys, i.e., the real and imaginary parts of the dielectric function (ε1,ε2) (or the index of refraction n and absorption coefficient α) versus photon energy E for the alloys. The alloys of interest include amorphous silicon–germanium (a-Si1−xGex:H) and silicon–carbon (a-Si1−xCx:H), with band gaps ranging continuously from ∼1.30 to 1.95 eV. The analytical expression incorporates the minimum number of physically meaningful, E independent parameters required to fit (ε1,ε2) versus E. The fit is performed simultaneously throughout the following three regions: (i) the below-band gap (or Urbach tail) region where α increases exponentially with E, (ii) the near-band gap region where transitions are assumed to occur between parabolic bands with constant dipole matrix element, and (iii) the above-band gap region where (ε1,ε2) can be simulated assuming a single Lorentz oscillator. The expression developed here provides an improved description of ε2 (or α) in the below-band gap and near-band gap regions compared with previous approaches. Although the expression is more complicated analytically, it has numerous applications in the analysis and simulation of thin film a-Si:H based p-i-n and n-i-p multilayer photovoltaic devices. First, we describe an approach whereby, from a single accessible measure of the optical band gap, the optical functions can be generated over the full solar spectrum for a sample set consisting of the highest quality intrinsic a-Si:H based alloys prepared by plasma-enhanced chemical vapor deposition using the principle of maximal H2 dilution. Second, we describe quantitatively how such an approach can be modified for sample sets consisting of lower quality alloy materials. Finally, we demonstrate how the generated optical functions can be used in simulations of the absorption, reflection, and quantum efficiency spectra of a-Si:H based single-junction and multijunction solar cells.
Explication and revision of generalized Van Vleck perturbation theory for molecular electronic structure
Authors: Khait Yuriy G. , Song Jie , Hoffmann Mark R.
Published: September 2002

A revision of second-order Generalized Van Vleck Perturbation Theory (GVVPT2) for the description of dynamic electron correlation in molecules is presented. It is shown that the basic formulas of the suggested method are well-defined approximations to the theoretically carefully constructed self-consistent quasidegenerate perturbation theory. Furthermore, it is shown that nonlinear responses to the perturbations can be obtained by explicit formulas. The revised GVVPT2 makes active use of the recently introduced concept of macroconfigurations, whereby vast numbers of null Hamiltonian matrix elements are prescreened with minimal computational cost and the remainders are organized for facile computation by Table-CI-like methodology. Moreover, use of macroconfigurations allows the efficient use of incomplete model spaces, which extends drastically the applicability of the method. Representative calculations on model systems studied previously with the original formulation show close agreement and on additional model systems show the wide applicability of the revised formulation.