bluuebunny/crossref_metadata_2025 huggingface dataset:
Interaction of capillary waves with longer waves. Part 2. Applications to
waves in two surface dimensions and to waves in shallow water
Authors: WATSON KENNETH M.
Published: July 2002

In Part 1 of this work we presented a new mathematical formulation for numerical
investigation of capillary wave dynamics. This permitted calculations to be readily
performed on a desktop computer. Applications given were primarily to waves in
one surface dimension. In Part 2 we describe further applications to waves in two
surface dimensions and also to waves in shallow water (not, however, shallow for the
capillary waves). Wavenumber–frequency spectra for wind waves are calculated. As
was observed in tank experiments by Hara et al. (1997), our calculations show both a
frequency spread and a frequency up-shifting which suggests that capillary waves are
‘dragged along’ by longer waves. Fine-scale roughness near wind wave crests shows a
transitory nature, changing with the wave pattern. We discuss implications of this for
microwave remote sensing. The propagation of short gravity waves in shallow water
is studied. As these waves develop bore-like forward faces, generation of parasitic
capillary waves is observed. Generation rates for these are substantially greater than
observed for waves in deep water.
On the competition between centrifugal and
shear instability in spiral Couette flow
Authors: MESEGUER A. , MARQUES F.
Published: July 2002

The linear stability of a fluid confined between two coaxial cylinders rotating independently
and with axial sliding (spiral Couette flow) is examined. A wide range
of experimental parameters has been explored, including two different radius ratios.
Zeroth-order discontinuities are found in the critical surface; they are explained as a
result of the competition between the centrifugal and shear instability mechanisms,
which appears only in the co-rotating case, close to the rigid-body rotation region.
In the counter-rotating case, the centrifugal instability is dominant. Due to the competition,
the neutral stability curves develop islands of instability, which considerably
lower the instability threshold. Specific and robust numerical methods to handle these
geometrical complexities are developed. The results are in very good agreement with
the experimental data available, and with previous computations.
Perturbation of low-frequency underwater acoustics by gravity waves
Authors: CHAMPY-DOUTRELEAU I. , EUVRARD D. , HAZARD C.
Published: July 2002

A body immersed in an ocean of large depth is assumed to vibrate and to radiate a
time-harmonic acoustic field of small amplitude in the presence of gravity waves of
small amplitude. Assuming both waves to have lengths of the same order (which in
practice corresponds to very low acoustic frequencies) it is shown that the diffraction
of acoustic waves by the corrugated free surface generates a second-order acoustic
pressure field p2. The computation of p2 involves a difficulty: a non-homogeneous
Dirichlet condition to be satisfied on the mean free surface up to infinity which implies
the absence of any clear indication about the condition that should be imposed at
infinity to have a well-posed problem. In order to get an insight into this difficult
problem the simple case of a point source is studied. We first judiciously choose one
solution and then show it is the physical solution using a limiting-amplitude procedure.
Coming back to the general case of a vibrating body the calculation of p2 is split
into two successive steps: the first one consists in computing an explicit convolution
product via numerical methods of integration, the second one is a standard radiation
problem that is solved using a method coupling a Green integral representation and
finite elements. A peak of the second-order pressure appears just above the vibrating
body.

The same concepts also apply to other second-order scattering problems, such as
the sea-keeping of weakly immersed submarines.
Words and feet
Authors: FUDGE ERIK
Published: July 2002

This article challenges the commonly-held assumption that words, feet and
syllables fit into a single phonological hierarchy, and in particular that feet
are always sub-units of words. A number of facts of English rhythm are cited
which cannot be accounted for unless words and feet are taken to be units
of different hierarchies: many of the differences of rhythm between phrases
of otherwise similar phonological structure which are noted by Abercrombie
(1964) are accounted for most naturally by differences in placement between,
on the one hand, word- and stress-group-boundaries, and, on the other, foot-boundaries.
Annual gametogenic cycle in ocean quahog, Arctica islandica from north-western Iceland
Authors: Thorarinsdóttir Gudrun G.
Published: July 2002

Annual gametogenic cycle in ocean quahog, Arctica islandica, was investigated using specimens collected regularly from a near shore population in north-western Iceland from December 1997 to November 1998. Gonads from 450 adult quahogs with shell length ranging from 65 to 106 mm were examined after being prepared by standard histological techniques. Observed gametogenic progression was categorized by five phases: (EA) early active; (LA) late active; (R) ripe; (PS) partially spent; (S) spent. All phases of the gametogenic cycle were present in the samples all the year around except in May and June when no spent individuals were seen, and in June and July when no individuals in the early active phase were observed. Morphologically ripe specimens predominated in the samples from May until August when partially spawned individuals dominated the population and did so until February. Spawning activity as inferred from the histological examination appears to be all the year around but most intense from June until August.
Surveys of the epibenthos of the Crouch Estuary (UK) in relation to TBT contamination
Authors: Rees H.L. , Waldock R. , Matthiessen P. , Pendle M.A.
Published: July 2002

The estuary of the River Crouch, south-east England, as sampled annually by beam trawl between 1987 and 1989, and again in 1992. The aim of an initial transect survey was to describe and quantify the subtidal epifauna at a time of high ambient tributyltin (TBT) concentrations, arising from the use of tin-based anti-fouling paints on the hulls of moored pleasure craft. Subsequent surveys at representative stations sought to examine the progress of any changes with time in animal populations in relation to a decline in concentrations of TBT in the environment, following a ban on the use of tin-based paints for smaller vessels in July 1987.
Gametogenesis and spawning in the subtidal white clam Spisula solida, in relation to temperature
Authors: Gaspar M.B. , Monteiro C.C.
Published: July 2002

Seasonal variations in reproductive cycle of Spisula solida were studied between June 1995 and June 1996 at a site off Vilamoura, southern Portugal. Sex ratio was found to be in favour of males. Both males and females showed a synchronism in gonadal development and spawning. Gametogenic activity started with decreasing temperature at the beginning of autumn. The onset of spawning took place in February when the seawater temperature began to increase. Spawning ended in May. It is possible that the white clam does not spawn at a definite temperature, rather responding to the increase in seawater temperature. Between June and September, the specimens were found to be in the resting stage and the condition index increased, probably due to the accumulation of reserves. Spisula solida reached maturity during the first year of life.
Quantifying daily migration in the sea urchin Paracentrotus lividus
Authors: Crook Anne C. , Long Maria , Barnes David K.A.
Published: July 2002

In Ireland the purple sea urchin Paracentrotus lividus (Echinoidea) typically inhabits intertidal bored holes. At Lough Hyne, Co. Cork, a population occurs associated with rock scree in the shallow subtidal zone. This study provides unequivocal quantitative evidence to demonstrate diurnal migration in a population of P. lividus at Lough Hyne, Ireland. Most size groups/age-classes did not to migrate, the youngest always and oldest never occurring under rocks. Those that did migrate between the lower and upper surface of rocks (2+, 3+ and 4+ age categories) did so in exactly the reverse circadian pattern to those described from the Mediterranean Sea.
Genome sizes of the entomopathogenic nematodes
Steinernema carpocapsae and Heterorhabditis bacteriophora
(Nematoda: Rhabditida)
Authors: GRENIER E. , CATZEFLIS F. M. , ABAD P.
Published: July 2002

There is currently no information on the genome size and complexity
in
the entomoparasitic nematodes Steinernema and
Heterorhabditis. DNA reassociation kinetics were used to determine
the
genome size and complexity in 2 species:
Steinernema carpocapsae and Heterorhabditis bacteriophora.
C0t curves derived from renaturation kinetics of denatured
DNA indicate that the genomes of these entomoparasitic rhabditids are different
both in size and complexity. Genome sizes were estimated at
2·3 × 108 bp for S. carpocapsae and
3·9 × 107 bp for H. bacteriophora and repetitive
DNA contents were found to represent 39% and 51% of these respective genomes.
Combining data from morphological traits and genetic
markers to determine transmission cycles in the
tape worm, Echinococcus granulosus
Authors: LYMBERY A. J.
Published: July 2002

Species of Echinococcus (Cestoda: Taeniidae) require 2
mammalian
hosts to complete their life-cycle; a carnivorous
definitive host, and a herbivorous or omnivorous intermediate host. For

most species of Echinococcus, the definitive host
range is restricted to 1 or a few species, but the intermediate host
range is very broad. Programmes to control hydatid
disease attempt to break the life-cycle of the parasite and their
effectiveness is therefore enhanced by an understanding
of local patterns of transmission. Although it is known that the
rostellar hooks of protoscoleces may be influenced by the
species of intermediate host in which they develop, the application
of this knowledge to infer transmission cycles has been
limited, because the intermediate host effect has not been isolated
from other environmental and genetic components of
phenotypic variance. This study presents a method for separating
these potentially confounding genetic and environmental
effects, by combining quantitative genetic analyses of hook traits
with data on population structure from neutral genetic
markers. The method was applied to 5 hook traits (hook number,
total length of large hooks, blade length of large hooks,
total length of small hooks, blade length of small hooks) measured
on protoscoleces from 2 intermediate host types (sheep
and macropod marsupials) in Australia. Although genetic variance
was similar for all traits, they differed markedly in the
extent of environmental variance attributed to development in
different host types. Total length of small hooks was the
trait most affected, with 49–60% of phenotypic variance being
explained by environmental differences between intermediate host
species. Blade length of small hooks was least
affected, with none of the phenotypic variance due to
intermediate host origin. These data suggest that hook measurements
of adult worms from naturally infected definitive
hosts could be used to determine the intermediate host species from
which infection was acquired, if the appropriate traits are measured.
Transmission of Borrelia afzelii from Apodemus mice
and
Clethrionomys voles to Ixodes ricinus ticks: differential

transmission pattern and overwintering maintenance
Authors: HUMAIR P. F. , RAIS O. , GERN L.
Published: July 2002

This study deals with the ecology of Lyme borreliosis in Europe.
The relationships between Borrelia burgdorferi sensu lato
spirochetes, Clethrionomys and Apodemus rodent reservoirs
and the Ixodes ricinus tick vector were investigated during 16

consecutive months in an enzootic area in Switzerland. Cultivation of ear
skin biopsies was used to isolate spirochetes from
C. glareolus, A. sylvaticus, A. flavicollis
and Glis glis. Borrelia infection was more frequently
observed in Clethrionomys
than in Apodemus. Tick xenodiagnosis was used to determine the
infectivity of rodents. The infection rate in ticks fed on
Clethrionomys was higher than that in ticks fed on Apodemus,
but Apodemus yielded more infected ticks than Clethrionomys

because of a better tick moulting success. Xenodiagnostic ticks were placed
into BSK medium to obtain isolates. Isolates
from rodents and rodent-feeding ticks were all identified as B. afzelii.
The follow-up of the infectivity status of repeatedly
recaptured rodents clearly demonstrated that these hosts remained infective
for ticks during winter till the following spring.
Comparing C. glareolus and A. sylvaticus, each rodent
species showed different host infection, different host infectivity
and contributed differently to the moulting success of feeding ticks. These
factors influence differentially the pattern of
transmission of B. afzelii from Clethrionomys voles and
Apodemus mice to I. ricinus ticks.
Characterization, cloning and immunogenicity of antigens
released by lung-stage larvae of Schistosoma mansoni
Authors: HARROP R. , COULSON P. S. , WILSON R. A.
Published: July 2002

Lung-stage schistosomula are the target of protective immunity in mice vaccinated with attenuated cercariae of Schistosoma
mansoni. Therefore, proteins present at this developmental stage, and in particular those which are secreted, are a potential
source of novel vaccine candidates. However, little information is available about such molecules. Here we describe the
cDNA clones identified by screening expression libraries with serum raised against proteins released by lung-stage
schistosomula. In total, 11 different cDNA species were identified, 6 of which have been described previously in S.
mansoni; these included fructose 1,6-bisphosphate aldolase and Sm21.7 which together accounted for two-thirds of all
positive clones. Of the 5 newly described schistosome genes, 1 cDNA had a high degree of homology to the s5a subunit
of 26S proteasomes, most significant being with the human protein. The remaining 4 clones showed no significant
homologies to any genes sequenced previously. Fructose 1,6-bisphosphate aldolase, Sm21.7, the proteasome homologue
and 1 unknown clone (A26) have been expressed in a bacterial expression system and serum produced against each
recombinant protein. Immunolocalization showed fructose 1,6-bisphosphate aldolase, Sm21.7 and the proteasome homologue
to be most abundant in muscle cells whilst clone A26 was distributed throughout many tissues, but was most
abundant in the tegument. Analysis of the cellular immune responses of vaccinated mice showed 3 of the 4 expressed
clones to be highly immunogenic, inducing the secretion of large quantities of the Th1-type cytokine interferon gamma.
IgG reactivities against recombinant Rhoptry-Associated
Protein-1 (rRAP-1) are associated with mixed Plasmodium
infections and protection against disease in Tanzanian children
Authors: ALIFRANGIS M. , LEMNGE M. M. , MOON R. , THEISEN M. , BYGBJERG I. , RIDLEY R. G. , JAKOBSEN P. H.
Published: July 2002

A cross-sectional sero-epidemiological study was performed in Magoda, Tanzania, an area where malaria is holoendemic.
Blood samples were collected from children (1–4 years) and tested for IgG antibody reactivity against 2 recombinant
protein fragments of Plasmodium falciparum Rhoptry-Associated Protein-1 (rRAP-1). The data were related to the
prevalence of malarial disease and single P. falciparum or mixed Plasmodium infections. Fever ([ges ]37·5 °C) in combination
with parasite densities >5000/μl were used to distinguish between children with asymptomatic malaria infections and
those with acute clinical disease. Furthermore, C-reactive protein (CRP) was applied as a surrogate marker of malaria
morbidity. The prevalence of Plasmodium infections was 96·0%. Eleven children were defined as clinical malaria cases,
all with single P. falciparum infections. The density of P. falciparum was significantly lower in children with mixed
Plasmodium infections compared to those with single P. falciparum infections. Children with asymptomatic P. falciparum
infections had higher IgG reactivities to rRAP-1, compared to IgG reactivities of children with malarial disease. Children
with mixed Plasmodium infections generally showed elevated IgG reactivity to rRAP-1, when compared to children with
single P. falciparum infections. The possible relationship between mixed species infections, clinical outcome of the disease
and antibody responses to RAP-1 is discussed.
Life events, difficulties and onset of depressive episodes in later life
Authors: I. BRILMAN ELS , ORMEL JOHAN
Published: July 2002

Background. The importance of stressful life events and long-term difficulties in the onset of episodes of unipolar depression is well established for young and middle-aged persons, but less so for older people.

Method. A prospective case–control study was nested in a large community survey of older people. We recruited 83 onset cases during a 2-year period starting 2½ years after the survey, via screening (N = 59) and GP monitoring (N = 24), and 83 controls, a random sample from the same survey population. We assessed depression with the PSE-10 and life stress exposure with the LEDS.

Results. Risk of onset was increased 22-fold by severe events and three-fold by ongoing difficulties of at least moderate severity. Severe events accounted for 21% of all episodes but ongoing difficulties for 45%. The association of onset with life stress, often health-related such as death, major disability and hospitalization of subject or someone close, was most pronounced in the cases identified by screening. While a clear risk threshold for events was found between threat 2 and 3 (on a scale of 1–4), the risk associated with difficulties increased more gradually with severity of difficulty. Compared with controls, severe events involved a larger risk for cases without a prior history of depression (OR = 39·48) than for cases with (OR = 8·86). The opposite was found for mild events (OR = 2·94 in recurrent episodes; OR = 1·09 in first episodes). The impact of ongoing difficulties was independent of severity of episode and history of depression.

Conclusion. Although the nature of life stress in later life, in particular health-related disability and loss of (close) social contacts, is rather different from that in younger persons, it is a potent risk factor for onset of a depressive episode in old age. Severe events show the largest relative risk, but ongoing difficulties account for most episodes. The association of severe events with onset tends to be stronger in first than in recurrent episodes. Mild events can trigger a recurrent episode but not a first one.
A validation study of the Hospital Anxiety and Depression Scale
(HADS) in different groups of Dutch subjects
Authors: SPINHOVEN PH. , ORMEL J. , SLOEKERS P. P. A. , KEMPEN G. I. J. M. , SPECKENS A. E. M. , HEMERT A. M. VAN
Published: July 2002

Background. Research on the dimensional structure and
reliability of the Hospital Anxiety and Depression Scale (HADS) and
its relationship with age is scarce. Moreover, its efficacy in
determining the presence of depression in different patient groups has
been questioned.

Methods. Psychometric properties of the HADS were assessed
in six different groups of Dutch subjects (N = 6165): (1) a
random sample of younger adults (age 18–65 years) (N =
199); (2) a random sample of elderly subjects of 57 to 65 years of age
(N = 1901); (3) a random sample of elderly subjects of 66
years or older (N = 3293); (4) a sample of consecutive
general practice patients (N = 112); (5) a sample of
consecutive general medical out-patients with unexplained somatic
symptoms (N = 169); and (6) a sample of consecutive
psychiatric out-patients (N = 491).

Results. Evidence for a two-factor solution corresponding
to the original two subscales of the HADS was found, although anxiety
and depression subscales were strongly correlated. Homogeneity and
test–retest reliability of the total scale and the subscales
were good. The dimensional structure and reliability of the HADS was
stable across medical settings and age groups. The correlations
between HADS scores and age were small. The total HADS scale showed a
better balance between sensitivity and positive predictive value (PPV)
in identifying cases of psychiatric disorder as defined by the Present
State Examination than the depression subscale in identifying cases of
unipolar depression as defined by ICD-8.

Conclusions. The moderate PPV suggests that the HADS is
best used as a screening questionnaire and not as a
‘case-identifier’ for psychiatric disorder or
depression.
Qualitative and quantitative analyses of a ‘lock and
key’ hypothesis of depression
Authors: PARKER G. , GLADSTONE G. , ROUSSOS J. , WILHELM K. , MITCHELL P. , HADZI-PAVLOVIC D. , AUSTIN M.-P. , HICKIE I.
Published: July 2002

Background. We examine a ‘lock and key’
(‘L–K’) hypothesis to depression which posits that early

adverse experiences establish locks that are activated by keys mirroring
the earlier adverse
experience to induce depression.

Methods. Two-hundred and seventy clinically depressed patients
were examined with open-ended
and pre-coded interview questions to ascertain both early adverse experiences
and precipitating life
events. Qualitative and quantitative data analyses examined for any associations
between
developmental ‘locks’ and precipitating ‘keys’.

Results. Qualitative assessment suggested ‘L–K’
links in almost one-third of the sample, and
examples are provided. While quantitative analyses indicated significant
associations between
several identical ‘lock’ and ‘key’ constructs,
evidence of specificity was rare. When individual
‘locks’ and ‘keys’ were consolidated into three
higher-order constructs, variable models were
suggested, including a non-specific link, a specific link and absence of
any link. ‘L–K’ links
appeared more likely in those with ‘non-melancholic’ (versus
‘melancholic’) depression, with the
seemingly greater relevance to ‘reactive’ (versus
‘neurotic’) depression in the quantitative analyses
inviting speculation that that ‘disorder’ may be more a reaction
to a salient rather than a severe
stressor.

Conclusions. This exploratory study suggests that early adverse
experiences may variably establish
specific and non-specific patterns of vulnerability to having depression
triggered by exposure to
salient mirroring life event stressors.
The Thought Control Questionnaire – psychometric
properties in a clinical sample, and relationships with
PTSD and depression
Authors: REYNOLDS MARTINA , WELLS ADRIAN
Published: July 2002

Background. Recent developments in research suggest that particular attempts to control thoughts
may contribute to the problem of intrusion. An instrument capable of identifying strategies for
dealing with unwanted intrusions in clinical populations may be used for differentiating between
thought control strategies that may or may not be helpful.

Methods. The Thought Control Questionnaire (TCQ) (Wells & Davies, 1994) developed and
validated on a normal sample, was administered to a clinical sample in order to investigate the
consistency of the original factor structure and its psychometric properties. The sensitivity of the
scale to change associated with recovery was also examined. Relationships between individual
differences in thought control strategies and psychiatric symptoms in patients with DSM-IV major
depression, and PTSD with or without major depression were investigated.

Results. The Scree Test suggested a six-factor solution which was rotated. This solution split the
original distraction subscale into separate behavioural and cognitive distraction, otherwise the
subscales were almost identical to those obtained in non-clinical subjects. As this split has been
shown to be unreliable, further analyses in this study were based on the five-factor version of the
TCQ obtained by Wells & Davies (1994). Predictors of recovery and of symptoms in PTSD and
depression were explored.

Conclusions. Correlations between the TCQ subscales and other measures suggest that particular
thought control strategies may be associated with the symptoms of PTSD and depression. The TCQ
scales appear to be sensitive to changes associated with recovery. Significant differences emerged
in thought control strategies between depressed and PTSD patients. Hierarchical regression
analysis showed distraction, punishment and reappraisal control strategies predicted depression
scores in depressed patients while use of distraction predicted intrusions in PTSD.
Schizophrenia among Surinamese in the Netherlands: high admission rates not explained by high emigration rates
Authors: BOGERS J. P. A. M. , DE JONG J. T. V. M. , KOMPROE I. H.
Published: July 2002

Background. A high risk of schizophrenia has been found among Caribbean immigrants in the
Netherlands and Great Britain. One hypothesis to explain these findings is that patients with a
diagnosis of schizophrenia or patients with symptoms of psychosis not specifically diagnosed,
emigrate more than the general population. Such selection might account for high rates of
Surinamese patients with a diagnosis of schizophrenia in Netherlands psychiatric hospitals. We
examined this hypothesis.

Methods. The files of patients with schizophrenia or patients suffering from unspecified psychosis
were selected from the archives of the National Psychiatric Hospital in Surinam. These patients were
traced to investigate patterns of emigration. Data from the Central Bureau for Statistics in the
Netherlands and from the Central Population Bureau in Surinam provided the percentage of the
general Surinamese population that emigrated to the Netherlands. The difference between the two
percentages was evaluated using the chi-squared test. Using the same method the percentage of
remigration from the Netherlands among Surinamese patients was compared with the percentage
of remigration among the general Surinamese population.

Results. Surinamese patients with schizophrenia or unspecified psychosis did not emigrate more
frequently to the Netherlands compared with the general Surinamese population. They did
remigrate significantly more frequently.

Conclusion. High migration rates do not explain the high hospital admission rates for schizophrenia
among Surinamese in the Netherlands.
Cognitive reserve and mortality in dementia: the role
of cognition, functional ability and depression
Authors: GEERLINGS M. I. , DEEG D. J. H. , PENNINX B. W. J. H. , SCHMAND B. , JONKER C. , BOUTER L. M. , VAN TILBURG W.
Published: July 2002

Objective. This study examined whether dementia patients with greater cognitive reserve had
increased mortality rates, and whether this association was different across strata of cognition,
functional ability and depression.

Methods. In the community-based Amsterdam Study of the Elderly, 261 non-institutionalized
dementia patients, identified using the Geriatric Mental State Schedule (GMS), were followed for an
average of 55·5 months after which mortality data were obtained. Cognitive reserve was indicated
by years of education and pre-morbid intelligence (measured using the Dutch Adult Reading
Test). Cognition, functional ability and depression were indicated by Mini-Mental State scores,
ADL and IADL measurements and GMS depressive syndrome, respectively.

Results. During the follow-up 146 persons (55·9%) died. Cox regression analyses showed that more
highly educated dementia patients had higher mortality rates, only if they had low MMSE scores
or if they had a concurrent depression. Pre-morbid intelligence was associated with a higher
mortality rate, independent of cognition, but this association was much stronger among patients
with depression. The positive association between education or intelligence and mortality was not
modified by functional disabilities.

Conclusions. The results suggest that dementia patients with greater cognitive reserve have
increased mortality rates, only if the disease has progressed to such an extent that clinical symptoms
are more severe. In this respect, the reserve hypothesis needs a modification. Depression in
dementia patients with greater cognitive reserve may reflect a subgroup of patients with poor
prognosis.
CCD detectors in high-resolution biological electron microscopy
Authors: Faruqi A. R. , Subramaniam Sriram
Published: July 2002

1. Introduction 1

1.1 The ‘band gap’ in silicon 2

2. Principles of CCD detector operation 3

2.1 Direct detection 3

2.2 Electron energy conversion into light 4

2.3 Optical coupling: lens or fibre optics? 6

2.4 Readout speed and comparison with film 8

3. Practical considerations for electron microscopic applications 9

3.1 Sources of noise 9

3.1.1 Dark current noise 9

3.1.2 Readout noise 9

3.1.3 Spurious events due to X-rays or cosmic rays 10

3.2 Efficiency of detection 11

3.3 Spatial resolution and modulation transfer function 12

3.4 Interface to electron microscope 14

3.5 Electron diffraction applications 15

4. Prospects for high-resolution imaging with CCD detectors 18

5. Alternative technologies for electronic detection 23

5.1 Image plates 23

5.2 Hybrid pixel detectors 24

6. References 26

During the past decade charge-coupled device (CCD) detectors have increasingly become the
preferred choice of medium for recording data in the electron microscope. The CCD detector
itself can be likened to a new type of television camera with superior properties, which makes
it an ideal detector for recording very low exposure images. The success of CCD detectors
for electron microscopy, however, also relies on a number of other factors, which include its
fast response, low noise electronics, the ease of interfacing them to the electron microscope,
and the improvements in computing that have made possible the storage and processing of
large images.

CCD detectors have already begun to be routinely used in a number of important
biological applications such as tomography of cellular organelles (reviewed by Baumeister,
1999), where the resolution requirements are relatively modest. However, in most high-
resolution microscopic applications, especially where the goal of the microscopy is to obtain
structural information at near-atomic resolution, photographic film has continued to remain
the medium of choice. With the increasing interest and demand for high-throughput structure
determination of important macromolecular assemblies, it is clearly important to have tools
for electronic data collection that bypass the slow and tedious process of processing images
recorded on photographic film.

In this review, we present an analysis of the potential of CCD-based detectors to fully
replace photographic film for high-resolution electron crystallographic applications.
On the utility of P3 amplitude as a measure of processing capacity
Authors: Kok Albert
Published: July 2002

The present review focuses on the utility of the amplitude of P3 of as a measure of processing capacity and mental workload. The paper starts with a brief outline of the conceptual framework underlying the relationship between P3 amplitude and task demands, and the cognitive task manipulations that determine demands on capacity. P3 amplitude results are then discussed on the basis of an extensive review of the relevant literature. It is concluded that although it has often been assumed that P3 amplitude depends on the capacity for processing task relevant stimuli, the utility of P3 amplitude as a sensitive and diagnostic measure of processing capacity remains limited. The major factor that prompts this conclusion is that the two principal task variables that have been used to manipulate capacity allocation, namely task difficulty and task emphasis, have opposite effects on the amplitude of P3. I suggest that this is because, in many tasks, an increase in difficulty transforms the structure or actual content of the flow of information in the processing systems, thereby interfering with the very processes that underlie P3 generation. Finally, in an attempt to theoretically integrate the results of the reviewed studies, it is proposed that P3 amplitude reflects activation of elements in a event‐categorization network that is controlled by the joint operation of attention and working memory.
Effects of aging on the novelty P3 during attend and ignore oddball tasks
Authors: Friedman David , Kazmerski Victoria A. , Cycowicz Yael M.
Published: July 2002

The effects of attention were assessed on novelty P3 amplitude and scalp distribution elicited by environmental sounds in young and elderly volunteers who participated in either actively attended or ignored oddball conditions. For the young, novelty P3 amplitude decreased with time on task during both attend and ignore sequences. Amplitude decrements were greatest at frontal sites during the attend condition, but at all sites during the ignore condition. A reliable amplitude decrement was not observed for the elderly in either the attend or ignore oddball series. The data suggest that attention differentially activates multiple generators that contribute to scalp‐recorded novelty P3 activity. The lack of novelty P3 habituation seen in the elderly is consistent with changes in frontal lobe function as age increases.
Long-term memory span
Authors: Nairne James S. , Neath Ian
Published: July 2002

Cowan assumes that chunk-based capacity limits are synonymous with the essence of a “specialized STM mechanism.” In a single experiment, we measured the capacity, or span, of long-term memory and found that it, too, corresponds roughly to the magical number 4. The results imply that a chunk-based capacity limit is not a signature characteristic of remembering over the short-term.
Quasi-modal encounters of the third kind: The filling-in of visual detail
Authors: Durgin Frank H.
Published: July 2002

Although Pessoa et al. imply that many aspects of the
filling-in debate may be displaced by a regard for active vision,
they remain loyal to naive neural reductionist explanations of certain
pieces of psychophysical evidence. Alternative interpretations are
provided for two specific examples and a new category of filling-in
(of visual detail) is proposed.
Talent scouts, not practice scouts: Talents are real
Authors: Rowe David C.
Published: July 2002

Howe et al. have mistaken gene x environment
correlations for environmental main effects. Thus, they believe that
training would develop the same level of performance in anyone, when
it would not. The heritability of talents indicates their dependence
on variation in physiological (including neurological) capacities.
Talents may be difficult to predict from early cues because tests are
poorly designed, or because the skill requirements change at more
advanced levels of performance. One twin study of training effects
demonstrated greater heritability of physical skill after
than before training. In summary, talents are real.
Individual differences in some special abilities are genetically influenced
Authors: Zohar Ada H.
Published: July 2002

There is a problem with the definition of talent as presented
by Howe et al. that makes it dependent on experts' ability
to detect it in the untrained. In addition, the choice of musical
performance as the example for innate talent is inappropriate,
and musical board results are selective and biased tests of it.
Outstanding mathematical reasoning ability offers much better
evidence of genetic influence.
Typical limit sets of critical points for smooth interval maps
Authors: BLOKH ALEXANDER , MISIUREWICZ MICHAŁ
Published: July 2002

We prove that interval maps for which $\omega$-limit sets of all critical points are minimal are dense in the space of all interval maps of class $C^2$.
Il n'y a pas de classification borélienne des homéomorphismes de Brouwer
Authors: LE ROUX FRÉDÉRIC
Published: July 2002

On considère l'espace {\mathcal B}_2 des homéomorphismes du plan obtenus en recollant deux translations, muni de la topologie compacte-ouverte. On construit une famille dans {\mathcal B}_2, continûment indexée par les éléments du Cantor \{0,1\}^\mathbb{Z}, pour laquelle les classes de conjugaison correspondent aux orbites du décalage (ou “ shift ”) sur \{0,1\}^\mathbb{Z}. Ceci permet de montrer qu'il n'y a pas de classification borélienne de la relation de conjugaison sur {\mathcal B}_2.
Simple ${\bi C}^*$-algebras arising from ${\beta}$-expansion of real numbers
Authors: KATAYAMA YOSHIKAZU , MATSUMOTO KENGO , WATATANI YASUO
Published: July 2002

Given a real number $\beta > 1$, we construct a simple purely infinite $C^*$-algebra ${\cal O}_{\beta}$ as a $C^*$-algebra arising from the $\beta$-subshift in the symbolic dynamics. The $C^*$-algebras $\{{\cal O}_{\beta} \}_{1<\beta \in {\Bbb R}}$ interpolate between the Cuntz algebras $\{{\cal O}_n\}_{1 < n \in {\Bbb N}}$. The K-groups for the $C^*$-algebras ${\cal O}_{\beta}$, $1 < \beta \in {\Bbb R}$, are computed so that they are completely classified up to isomorphism. We prove that the KMS-state for the gauge action on ${\cal O}_{\beta}$ is unique at the inverse temperature $\log \beta$, which is the topological entropy for the $\beta$-shift. Moreover, ${\cal O}_{\beta}$ is realized to be a universal $C^*$-algebra generated by $n-1=[\beta]$ isometries and one partial isometry with mutually orthogonal ranges and a certain relation coming from the sequence of $\beta$-expansion of $1$.
Corrections to ‘Invariant measures for higher-rank hyperbolic abelian actions’
Authors: KATOK A. , SPATZIER R. J.
Published: July 2002

The proofs of Theorems 5.1 and 7.1 of [2] contain a gap. We will show below how to close it under some suitable additional assumptions in these theorems and their corollaries. We will assume the notation of [2] throughout. In particular, $\mu$ is a measure invariant and ergodic under an $R^k$-action $\alpha$. Let us first explain the gap. Both theorems are proved by establishing a dichotomy for the conditional measures of $\mu$ along the intersection of suitable stable manifolds. They were either atomic or invariant under suitable translation or unipotent subgroups $U$. Atomicity eventually led to zero entropy. Invariance of the conditional measures showed invariance of $\mu$ under $U$. We then claimed that $\mu$ was algebraic using, respectively, unique ergodicity of the translation subgroup on a rational subtorus or Ratner's theorem (cf. [2, Lemma 5.7]). This conclusion, however, only holds for the $U$-ergodic components of $\mu$ which may not equal $\mu$. In fact, in the toral case, the $R^k$-action may have a zero-entropy factor such that the conditional measures along the fibers are Haar measures along a foliation by rational subtori. Since invariant measures with zero entropy have not been classified, we cannot conclude algebraicity of the total measure $\mu$ at this time. In the toral case, the existence of zero entropy factors turns out to be precisely the obstruction to our methods. The case of Weyl chamber flows is somewhat different as the ‘Haar’ direction of the measure may not be integrable. In this case, we need to use additional information coming from the semisimplicity of the ambient Lie group to arrive at the versions of Theorem 7.1 presented below.
Dynamics of $(e^{z} - 1)/z$: the Julia set and bifurcation
Authors: KAPOOR G. P. , GURU PREM PRASAD M.
Published: July 2002

We describe the dynamical behaviour of the entire transcendental non-critically finite function $f_\lambda (z) = \lambda(e^z - 1)/z$, $\lambda > 0$. Our main result is to obtain a computationally useful characterization of the Julia set of $f_\lambda (z)$ as the closure of the set of points with orbits escaping to infinity under iteration, which in turn is applied to the generation of the pictures of the Julia set of $f_\lambda (z)$. Such a characterization was hitherto known only for critically finite entire transcendental functions [11]. We find that bifurcation in the dynamics of $f_\lambda (z)$ occurs at $\lambda = \lambda^{*}$ ($\approx 0.64761$) where $\lambda^\ast = {(x^{*})}^{2} /({e}^{x^{*}} -1)$ and $x^{*}$ is the unique positive real root of the equation $e^{x}(2 -x ) -2 = 0$.
Quasi-states, weak states and the partition of Africa
Authors: HOPKINS A. G.
Published: July 2002

The paths taken by historians and political scientists intersect less frequently than
their subject matter might indicate. Both sets of scholars, for example, have a mutual
interest in the formation and evolution of the modern state. However, while this
interest has made the ‘Westphalian system’ the common currency of exchanges
among political scientists, few historians refer to the concept, and some would not
recognize it—even at close range and in full sunlight. Practitioners of the two disciplines
often pass like ships in the night because they are unaware of another large
presence on a parallel course. In an age of intense specialization we readily become
separated, like Alfred Marshall's noncompeting wage groups, from a common body
of information. A more formally acceptable justification for discrete enquiries into
similar problems lies in the claim that the disciplines have different purposes. The
distinction is not, as is still so often said, that historians are interested in the unique
and social scientists in the general; it is rather that the analytical issues forming the
generalizations that necessarily accompany statements about large issues are of a
different order. Political scientists assign significance to the Westphalian system
mainly because they wish to generalize about the principles governing the international
regime of sovereign states after 1648. Historians, on the other hand, are less
interested in testing the merits of realism and its rivals than in charting changing
relativities in international relations. Accordingly, they are more likely to set the
Westphalian settlement in the context of already evolving state systems and of subsequent
changes of equal or greater moment, such as the upheavals caused by the
French and American revolutions.
Three-finger SMA robot hand and its practical analysis
Authors: Dilibal Savas , Guner Ertan , Akturk Nizami
Published: July 2002

Gripping of different types of objects with a multi-finger robot hand is a vital task for robot arms. Grippers, which are end effector elements in robot applications, are employed in various industrial operations such as transferring, assembling, welding and painting. However, if a gripper is considered for handling different jobs or to carry different types of parts in an assembly line, a general-purpose robot hand is going to be required. There are various technological actuators of robot hands such as electrical, hydraulic and pneumatic motors, etc. Besides these conventional actuators, it is possible to
include Shape Memory Alloys (SMA) in the category of technological actuators. The SMA can give materials motion by moving to a predetermined position, at a specific temperature. The conversion of this motion to a gripping action of the robot hand is the heart of the matter. In this study, a robot hand is developed using Ni-Ti SMA and a set of experiments were performed in order to check the compatibility of the system in an industrial environment.
A generalised approach for the modelling of articulated open chain planar linkages
Authors: Baysec Sedat , Rees Jones John
Published: July 2002

In this paper a model to cover all possible topologies of
robot manipulators composed of prismatic and revolute joints is presented.
For simplicity, only planar systems are considered, hence to provide plane
positioning, systems handled are of three degrees of freedom. The physical
model assumes three moving rigid links in articulation with one revolute and
one prismatic joint between each link pair, forming a six degrees of freedom
open chain linkage. Among each joint pair, one is real and the other
fictitious. The real joint is arbitrarily actuated by an externally applied
force or torque while the fictitious one is acted upon by an appropriately
controlled force or torque as to keep that joint velocity zero, keeping
fixed at its initial position. The physical model is accompanied by a
mathematical model obtained by Lagrange formulation. This approach is
called ‘The method of Fictititous Degrees of Freedom’.
A NEW METHOD FOR OBTAINING THE AUTOCOVARIANCE OF AN ARMA
MODEL: AN EXACT FORM SOLUTION
Authors: Karanasos Menelaos
Published: July 2002

Karanasos (1998) presented a new method for computing
the theoretical autocovariance function (acf) of the following
univariate autoregressive moving average (ARMA) model:

Φ(L)yt =
Θ(L)εt

where

Φ(L) = 1 − φ1L −
… − φpLp,
Θ(L) = 1 − θ1L −
… − θqLq
EFFICIENT DETRENDING IN COINTEGRATING REGRESSION
Authors: Xiao Zhijie , Phillips Peter C.B.
Published: July 2002

This paper studies efficient detrending in cointegrating
regression and develops modified tests for cointegration
that use efficient detrending procedures. Asymptotics for
these tests are derived. Monte Carlo experiments are conducted
to evaluate the detrending procedures in finite samples
and to compare tests for cointegration based on different
detrending procedures. The limit theory allows for increasingly
remote initial condition effects as the sample size goes
to infinity.
Food habits of Cynopterus brachyotis (Muller)
(Chiroptera: Pteropodidau) in Peninsular Malaysia
Authors: TAN K. H. , ZUBAID A. , KUNZ T. H.
Published: July 2002

Information on the feeding habits of the the lesser dog-faced friut bat, Cynopterus brachyotis, was obtained by the collection of food remains directly beneath daytime and feeding roosts. The bats were found to feed on the fruits of 54 plant species, the leaves of 14 species and the flower parts of four species. The seasonal phenological differences among congeneric plant species led to steady production of fruit throughout the year and the data suggets that Ficus spp. are a key component in the diet. Judging from its wide selection of fruits, C. brachyotis, is considered to be an important seed disperser. Folivory in C. brachyotis appears to be more common than previously thought. Of the leaves consumed by the bats, seven species belonged to the family Leguminosae, followed by Myrtaccae, Moraccae, Rhizophoacae and Euphorbiaccae. Friuts in general, provide an energy rich diet for phytophagous bats but most are low in protein. In contrast, leaves consumed by bats have a relatively high protein content. We suggest that folivory (by leaf fractionation) should be energetically more advantageous than the ingestion of large amounts of low protein friut or the active pursuit of mobile insects.
Branch-and-cut for combinatorial optimization problems without auxiliary binary variables
Authors: DE FARIAS I. R. , JOHNSON E. L. , NEMHAUSER G. L.
Published: July 2002

Many optimisation problems involve combinatorial constraints on continuous variables. An example of a combinatorial constraint is that at most one variable in a group of nonnegative variables may be positive. Traditionally, in the mathematical programming community, such problems have been modeled as mixed-integer programs by
introducing auxiliary binary variables and additional constraints. Because the number of variables and constraints becomes larger and the combinatorial structure is not used to advantage, these mixed-integer programming models may not be solved satisfactorily, except for small instances. Traditionally, constraint programming approaches to such problems keep and use the combinatorial structure, but do not use linear programming bounds in the search for an optimal solution. Here we present a branch-and-cut approach that considers the combinatorial constraints without the introduction of binary variables. We review the development of this approach and show how strong constraints can be derived using ideas from polyhedral combinatorics. To illustrate the ideas, we present a production scheduling model that arises in the manufacture of fibre optic cables.