bluuebunny/crossref_metadata_2025 huggingface dataset:
On Developing Self‐concepts: A Controlled Study of Children and Adolescents with Autism
Authors: Lee Anthony , Hobson R. Peter
Published: August 2003

This study employed the self‐understanding interview of Damon and Hart (1988) to assess the self‐concepts of two groups of children and adolescents: a group of individuals with autism and a group of nonautistic mentally retarded individuals who were matched for age and for verbal ability. On the basis of an hypothesis concerning the interpersonal origins of social and psychological self‐concepts (Hobson, 1990; Neisser, 1988), it was predicted that the participants with autism would show a relative dearth of such concepts in their talk about themselves. In accordance with our predictions, there was a significant group difference in the number and quality of statements that fell into the social category of self‐concept; contrary to our predictions, however, there was no group difference in the number of statements that fell into the psychological category. In addition, although there were not significant group differences in the overall production of verbally expressed concepts concerning self‐attributes of a physical, active, or psychological kind, even within these categories individuals with autism made fewer references to social interactions or qualities. These results are discussed with regard to theories of self‐concept development in typically developing as well as autistic and mentally retarded individuals, and with reference to the limitations of interpersonal understanding (“theory of mind”) in people with autism.
Genetics and Child Psychiatry: I Advances in Quantitative and Molecular Genetics
Authors: Rutter Michael , Silberg Judy , O'Connor Thomas , Simonoff Emily
Published: August 2003

Advances in quantitative psychiatric genetics as a whole are reviewed with respect to conceptual and methodological issues in relation to statistical model fitting, new genetic designs, twin and adoptee studies, definition of the phenotype, pervasiveness of genetic influences, pervasiveness of environmental influences, shared and nonshared environmental effects, and nature‐nurture interplay. Advances in molecular genetics are discussed in relation to the shifts in research strategies to investigate multifactorial disorders (affected relative linkage designs, association strategies, and quantitative trait loci studies); new techniques and identified genetic mechanisms (expansion of trinucleotide repeats, genomic imprinting, mitochondrial DNA, fluorescent in‐situ hybridisation, behavioural phenotypes, and animal models); and the successful localisation of genes.
Intrusive and Withdrawn Behaviours of Mothers Interacting with Their Infants and Boyfriends
Authors: Hart Sybil , Field Tiffany , Jones Nancy , Yando Regina
Published: August 2003

Investigated stability and change in intrusive and withdrawn interaction behaviours of 23 mothers in Study 1 and 31 mothers in Study 2. Comparisons between mother‐infant and mother‐boyfriend interactions revealed that mothers who had been withdrawn with their infants were quiet, bored‐looking, physically distant, and underinvolved with their boyfriends. Mothers who had been intrusive with their infants were verbally sharp and controlling with their boyfriends. These findings suggested stability across social contexts. Comparing maternal responding to instructions to think about themselves (self‐focus) or their infants (infant‐focus) revealed that infant‐focusing attenuated intrusive behavior among intrusive mothers and self‐focusing attenuated negative affect among withdrawn mothers. These findings suggested that cognitive focusing ameliorates nonoptimal maternal behaviours and has differential effects on intrusive and withdrawn mothers.
Wealth Effects of Diversification and Financial Deal Structuring: Evidence from REIT Property Portfolio Acquisitions
Authors: Campbell Robert D. , Petrova Milena , Sirmans C. F.
Published: August 2003

This study examines the strategic characteristics and shareholder wealth effects of a popular vehicle for Real Estate Investment Trust growth in the 1990s: the acquisition of a portfolio of properties from a single seller. We examine a sample of 209 REIT portfolio acquisitions during 1995‐2001. We observe a wide variety of financing strategies and find an array of different categories of sellers. Contrary to results reported in real estate transactions of this sort in the past, we find that announcement‐period shareholder returns are significantly positive in the aggregate. We present evidence that excess returns to acquirers result from (1) wealth benefits received when companies reconfirm their geographical focus in the acquisition, (2) positive information conveyed by the use of project‐specific private debt and (3) a positive signal sent to the market when transactions are financed by stock privately placed with financial institutions.
Inside Ownership, Risk Sharing and Tobin's q‐Ratios: Evidence from REITs
Authors: Capozza Dennis R. , Seguin Paul J.
Published: August 2003

We investigate relations among inside ownership, managerial expenses, risk sharing and equity valuations. Our engine of analysis—Real Estate Investment Trusts (REITs)—provides a unique and rich framework for analysis since we can calculate extremely accurate measures of asset replacement costs, and hence relative valuation (Tobin's q). Further, the nature of the financial statements allows us to examine the impact of insider ownership on agency costs since we can accurately measure the costs of the entire management team. Our results show that firms with greater insider holdings tend to invest in assets with lower systematic risk and use less debt in their capital structure. At the same time, managerial expenses are lower as inside ownership increases. Finally, higher levels of insider ownership are associated with higher relative valuation as measured by both higher premiums to net asset value and higher multiples of cash flows. The results have implications for the design of optimal management contracts for both REITs and firms in general.
Technocracies, Bureaucracies, or Responsive Polities? Urban School Systems and the Politics of School Violence Prevention*
Authors: Hess Frederick M. , Leal David L.
Published: August 2003

Objective.Two tacks are implicit in the seminalChubb and Moe (1990)argument that education bureaucracies tend to be rigidified by democratic conflict. One emphasizes the vulnerability of urban systems to organized interests and community pressures; the other argues that urban systems are unresponsive and ossified bureaucracies. This debate contrasts with traditional assumptions of apolitical “professionalism.” The predictive power of these theses is examined for the case of school violence prevention policy.

Methods.Ordinary least squares regression analysis is conducted on the 1995 Council of Urban Boards of Education survey, encompassing 74 urban school districts.

Results.Districts with greater levels of racial violence and violence against teachers had more school violence prevention measures. Levels of general school violence and district perceptions of school violence were not statistically significant.

Conclusions.Urban systems are quite responsive to interest group pressure as well as to high SES communities. The professionalism thesis is not supported.
Third‐Party Candidates and the 2000 Presidential Election*
Authors: Magee Christopher S. P.
Published: August 2003

Objective. This article examines how third‐party candidates influenced the 2000 presidential election.

Methods. Two surveys provide information on a hypothetical election between only George Bush and Al Gore. The determinants of voting behavior in this election are then used to estimate how votes cast for third‐party candidates would have been partitioned between Bush, Gore, and abstentions had the other candidates dropped out of the race.

Results. The estimates suggest that the Ralph Nader votes would have gone primarily to Gore (giving him the win in Florida) while Bush would have received more of the Pat Buchanan votes. The results also show that Nader's presence in the race gave Gore an incentive to position himself farther to the left ideologically. Bush's ideological position was not affected by Buchanan's participation.

Conclusion. The third‐party candidates' participation was a critical factor in George Bush's Electoral College victory over Al Gore.
Ideological Realignment in the Contemporary U.S. Electorate Revisited*
Authors: Schreckhise William D. , Shields Todd G.
Published: August 2003

Objective. In this study, we revisit the ideological‐realignment theory proposed by Abramowitz and Saunders (1998) by assessing the varying impact a person's ideology had on his or her partisan identification for individuals in different regions and between men and women.

Method. Through an examination of the NES cumulative data file and the 1992–1994 NES Panel Study, we present a series of tabular findings, an OLS regression model, and partial correlation coefficients to assess these changing subgroup dynamics.

Results. Between 1978 and 1994, the impact of a person's ideology on his or her party identification grew in magnitude, while the impact of respondents' parental party identification on their own party identification waned. However, these changes were not felt uniformly throughout the electorate, with Southern white males and Southern white females exhibiting the greatest changes. In the case of Southern white males, racial issues now appear to be related to their party identification.

Conclusion. We find support for the ideological‐realignment theory, but find evidence that such changes occurred rather unevenly throughout the electorate, suggesting that different dynamics of realignment may be at work simultaneously.
Residential Mobility and Children's Social Capital: Evidence from an Experiment*
Authors: Pettit Becky , McLanahan Sara
Published: August 2003

Objective. This article examines the effects of residential mobility on social connections that are likely to affect children's well‐being.

Methods. We use data from a survey of participants in a housing experiment in Los Angeles, California to examine whether families that moved from public housing projects to other neighborhoods suffered short‐term losses of social capital.

Results. Results indicate that residential mobility is associated with a reduced likelihood of parents talking with the parents of their children's friends. However, the effects of residential mobility on social capital are sensitive to adjustments for poverty levels in destination neighborhoods and factors that influence the probability of moving.

Conclusions. Our results suggest that at least some of the negative effects of moving shown in previous studies may be due to negative selection. That is, families that move may be less successful at developing social ties than families that do not move. This finding suggests that future research on residential mobility needs to pay closer attention to factors that influence why and where families move.
Wealth, Race, and Mortality*
Authors: Bond Huie Stephanie A. , Krueger Patrick M. , Rogers Richard G. , Hummer Robert A.
Published: August 2003

Objective. We explore, first, whether wealth relates to mortality risk independent of income and education, and second, whether wealth closes the black‐white gap in U.S. adult mortality while controlling for other socioeconomic and sociodemographic factors.

Methods. We employ the Cox proportional hazards models on data from the 1992 wave of the Health and Retirement Study linked to deaths through 1998, to analyze pre‐retirement adult mortality in the United States.

Results. The findings suggest that broader measures of SES, including wealth, are significant for understanding adult mortality. Further, vastly lower asset holdings among blacks, compared to whites, not only affects their financial well‐being but also their survival prospects.

Conclusions. Research and social policies that aim to understand and close health disparities in the United States may be poorly conceived if they ignore the impact of wealth on premature adult mortality.
Coherent Spin Transfer Between Molecularly Bridged Quantum Dots
Authors: Ouyang Min , Awschalom David D.
Published: August 2003

Femtosecond time-resolved Faraday rotation spectroscopy reveals the instantaneous transfer of spin coherence through conjugated molecular bridges spanning quantum dots of different size over a broad range of temperature. The room-temperature spin-transfer efficiency is ∼20%, showing that conjugated molecules can be used not only as interconnections for the hierarchical assembly of functional networks but also as efficient spin channels. The results suggest that this class of structures may be useful as two-spin quantum devices operating at ambient temperatures and may offer promising opportunities for future versatile molecule-based spintronic technologies.
Survival of
Salmonella enterica
in Freshwater and Sediments and Transmission by the Aquatic Midge
Chironomus tentans
(Chironomidae: Diptera)
Authors: Moore Barry C. , Martinez Edward , Gay John M. , Rice Daniel H.
Published: August 2003

Survival of a nalidixic acid-resistant strain of
Salmonella enterica
serovar Typhimurium mr-DT-104 in water and sediments was tested using artificially contaminated aquaria. Water samples remained culture positive for salmonella for up to 54 days. Sediment samples were culture positive up to 119 days. In addition, potential mechanisms for spreading salmonella in the environments by chironomid larvae and adults were tested. We evaluated the acquisition of mr-DT-104 by chironomids from contaminated aquatic sediments and subsequent spread to uncontaminated sediments. Larval chironomids raised in contaminated sediments became culture positive, and the bacteria were carried over to adults after emergence. Contamination of clean sediments by chironomid larvae was not demonstrated. These findings clearly suggest that mr-DT-104 serovar organisms can survive in aquatic sediments for at least several months. Uptake of salmonellae by chironomid larvae and adults suggests that they are possible vectors of mr-DT-104 in both aquatic and terrestrial environments, although the role of larval defecation in movement of bacteria to new sediments was not demonstrated.
The Mode of Action of the
Bacillus thuringiensis
Vegetative Insecticidal Protein Vip3A Differs from That of Cry1Ab δ-Endotoxin
Authors: Lee Mi Kyong , Walters Frederick S. , Hart Hope , Palekar Narendra , Chen Jeng-Shong
Published: August 2003

The Vip3A protein, secreted by
Bacillus
spp. during the vegetative stage of growth, represents a new family of insecticidal proteins. In our investigation of the mode of action of Vip3A, the 88-kDa Vip3A full-length toxin (Vip3A-F) was proteolytically activated to an approximately 62-kDa core toxin either by trypsin (Vip3A-T) or lepidopteran gut juice extracts (Vip3A-G). Biotinylated Vip3A-G demonstrated competitive binding to lepidopteran midgut brush border membrane vesicles (BBMV). Furthermore, in ligand blotting experiments with BBMV from the tobacco hornworm,
Manduca sexta
(Linnaeus), activated Cry1Ab bound to 120-kDa aminopeptidase N (APN)-like and 250-kDa cadherin-like molecules, whereas Vip3A-G bound to 80-kDa and 100-kDa molecules which are distinct from the known Cry1Ab receptors. In addition, separate blotting experiments with Vip3A-G did not show binding to isolated Cry1A receptors, such as
M. sexta
APN protein, or a cadherin Cry1Ab ecto-binding domain. In voltage clamping assays with dissected midgut from the susceptible insect,
M. sexta,
Vip3A-G clearly formed pores, whereas Vip3A-F was incapable of pore formation. In the same assay, Vip3A-G was incapable of forming pores with larvae of the nonsusceptible insect, monarch butterfly,
Danaus plexippus
(Linnaeus). In planar lipid bilayers, both Vip3A-G and Vip3A-T formed stable ion channels in the absence of any receptors, supporting pore formation as an inherent property of Vip3A. Both Cry1Ab and Vip3A channels were voltage independent and highly cation selective; however, they differed considerably in their principal conductance state and cation specificity. The mode of action of Vip3A supports its use as a novel insecticidal agent.
Characterization of
Escherichia coli
O157:H7 from Downer and Healthy Dairy Cattle in the Upper Midwest Region of the United States
Authors: Byrne C. M. , Erol I. , Call J. E. , Kaspar C. W. , Buege D. R. , Hiemke C. J. , Fedorka-Cray P. J. , Benson A. K. , Wallace F. M. , Luchansky J. B.
Published: August 2003

While cattle in general have been identified as a reservoir of
Escherichia coli
O157:H7, there are limited data regarding the prevalence and clonality of this pathogen in downer dairy cattle and the potential impact to human health that may occur following consumption of meat derived from downer dairy cattle. In the present study, conducted at two slaughter facilities in Wisconsin between May and October of 2001, we established a higher prevalence of
E. coli
O157:H7 in fecal and/or tissue samples obtained aseptically from intact colons of downer dairy cattle (10 of 203, 4.9%) than in those from healthy dairy cattle (3 of 201, 1.5%). Analyses of 57 isolates, representing these 13 positive samples (one to five isolates per sample), by pulsed-field gel electrophoresis, revealed 13 distinct
Xba
I restriction endonuclease digestion profiles (REDP). Typically, isolates from different animals displayed distinct REDP and isolates from the same fecal or colon sample displayed indistinguishable REDP. However, in one sample, two different, but highly related, REDP were displayed by the isolates recovered. Antimicrobial susceptibility testing indicated that 10 of the 57 isolates, recovered from 2 (1 downer and 1 healthy animal) of the 13 positive samples, were resistant to at least 1 of 18 antimicrobials tested. However, there was no appreciable difference in the frequency of resistance of isolates recovered from downer and healthy dairy cattle, and not all isolates with the same REDP displayed the same antimicrobial susceptibility profile. Lastly, it was not possible to distinguish between isolates recovered from downer and healthy cattle based on their
Xba
I REDP or antimicrobial susceptibility. These results indicate that downer cattle had a 3.3-fold-higher prevalence of
E. coli
O157:H7 than healthy cattle within the time frame and geographic scope of this study.
A Cytochrome
c
from a Lupanine-Transforming
Pseudomonas putida
Strain Is Expressed in
Escherichia coli
during Aerobic Cultivation and Efficiently Exported and Assembled in the Periplasm
Authors: Kaderbhai Mustak A. , Hopper David J. , Akhtar Kalim M. , Abbas Syed K. , Kaderbhai Naheed N.
Published: August 2003

We have cloned, sequenced, and heterologously expressed a periplasmic cytochrome
c
from a lupanine-utilizing
Pseudomonas putida
strain. Aerobic batch cultivation of
Escherichia coli
TB1 harboring the cytochrome
c
gene placed downstream of the
lac
promoter in pUC9 vector resulted in significant production of the holo-cytochrome
c
in the periplasm (∼4 mg of hemoprotein/liter of culture). The recombinant cytochrome
c
was purified to homogeneity and was found to be functional in accepting electrons from lupanine hydroxylase while catalyzing hydroxylation of lupanine. Comparison of the N-terminal amino acid sequence of the isolated cytochrome
c
with that deduced from the DNA sequence indicated that the signal sequence was processed at the bond position predicted by the SigPep program. The molecular size of the cytochrome
c
determined by electrospray mass spectrometry (9,595) was in precise agreement with that predicted from the nucleotide sequence.
Real-Time PCR Detection of
Brucella abortus
: a Comparative Study of SYBR Green I, 5′-Exonuclease, and Hybridization Probe Assays
Authors: Newby D. T. , Hadfield T. L. , Roberto F. F.
Published: August 2003

Real-time PCR provides a means of detecting and quantifying DNA targets by monitoring PCR product accumulation during cycling as indicated by increased fluorescence. A number of different approaches can be used to generate the fluorescence signal. Three approaches—SYBR Green I (a double-stranded DNA intercalating dye), 5′-exonuclease (enzymatically released fluors), and hybridization probes (fluorescence resonance energy transfer)—were evaluated for use in a real-time PCR assay to detect
Brucella abortus
. The three assays utilized the same amplification primers to produce an identical amplicon. This amplicon spans a region of the
B. abortus
genome that includes portions of the
alkB
gene and the IS
711
insertion element. All three assays were of comparable sensitivity, providing a linear assay over 7 orders of magnitude (from 7.5 ng down to 7.5 fg). However, the greatest specificity was achieved with the hybridization probe assay.
Strain-Specific Ureolytic Microbial Calcium Carbonate Precipitation
Authors: Hammes Frederik , Boon Nico , de Villiers Johan , Verstraete Willy , Siciliano Steven Douglas
Published: August 2003

During a study of ureolytic microbial calcium carbonate (CaCO
3
) precipitation by bacterial isolates collected from different environmental samples, morphological differences were observed in the large CaCO
3
crystal aggregates precipitated within bacterial colonies grown on agar. Based on these differences, 12 isolates were selected for further study. We hypothesized that the striking differences in crystal morphology were the result of different microbial species or, alternatively, differences in the functional attributes of the isolates selected. Sequencing of 16S rRNA genes showed that all of the isolates were phylogenetically closely related to the
Bacillus sphaericus
group. Urease gene diversity among the isolates was examined by using a novel application of PCR-denaturing gradient gel electrophoresis (DGGE). This approach revealed significant differences between the isolates. Moreover, for several isolates, multiple bands appeared on the DGGE gels, suggesting the apparent presence of different urease genes in these isolates. The substrate affinities (

K
m

) and maximum hydrolysis rates (
V
max
) of crude enzyme extracts differed considerably for the different strains. For certain isolates, the urease activity increased up to 10-fold in the presence of 30 mM calcium, and apparently this contributed to the characteristic crystal formation by these isolates. We show that strain-specific calcification occurred during ureolytic microbial carbonate precipitation. The specificity was mainly due to differences in urease expression and the response to calcium.
Identification and Characterization of Two Subpopulations of
Encephalitozoon intestinalis
Authors: Hoffman Rebecca M. , Marshall Marilyn M. , Polchert David M. , Helen Jost B.
Published: August 2003

Microsporidia are obligate intracellular protozoa that have been shown to be pathogenic to most living creatures. The development of in vitro cell culture propagation methods has provided researchers with large numbers of spores and facilitated the study of these organisms. Here, we describe heterogeneity within cell culture-propagated
Encephalitozoon intestinalis
suspensions. Flow cytometer histograms depicting the log side scatter and forward-angle light scatter of spores from nine suspensions produced over 12 months consistently showed two populations differing in size. The suspensions were composed primarily of the smaller-spore subpopulation (76.4% ± 5.1%). The presence of two subpopulations was confirmed by microscopic examination and image analysis (
P
< 0.001). Small subpopulation spores were noninfectious in rabbit kidney (RK13) cell culture infectivity assays, while the large spores were infectious when inocula included ≥25 spores. The small spores stained brilliantly with fluorescein isothiocyanate-conjugated monoclonal antibody against
Encephalitozoon
genus spore wall antigen, while the large spores stained poorly. There was no difference in staining intensities using commercial (MicroSporFA) and experimental polyclonal antibodies. Vital-dye (DAPI [4′,6′-diamidino-2-phenylindole], propidium iodide, or SYTOX Green) staining showed the spores of the small subpopulation to be permeable to all vital dyes tested, while spores of the large subpopulation were not permeable in the absence of ethanol pretreatment. PCR using primers directed to the 16S rRNA or β-tubulin genes and subsequent sequence analysis confirmed both subpopulations as
E. intestinalis
. Our data suggest that existing cell culture propagation methods produce two types of spores differing in infectivity, and the presence of these noninfective spores in purified spore suspensions should be considered when designing disinfection and drug treatment studies.
Identification and Application of Plasmids Suitable for Transfer of Foreign DNA to Members of the Genus
Gordonia
Authors: Arenskötter Matthias , Baumeister Dirk , Kalscheuer Rainer , Steinbüchel Alexander
Published: August 2003

Gene transfer systems for
Gordonia polyisoprenivorans
strains VH2 and Y2K based on electroporation and conjugation, respectively, were established. Several parameters were optimized, resulting in transformation efficiencies of >4 × 10
5
CFU/μg of plasmid DNA. In contrast to most previously described electroporation protocols, the highest efficiencies were obtained by applying a heat shock after the intrinsic electroporation. Under these conditions, transfer and autonomous replication of plasmid pNC9503 was also demonstrated to proceed in
G. alkanivorans
DSM44187,
G. nitida
DSM44499
T
,
G. rubropertincta
DSM43197
T
,
G. rubropertincta
DSM46038, and
G. terrae
DSM43249
T
. Conjugational plasmid DNA transfer to
G. polyisoprenivorans
resulted in transfer frequencies of up to 5 × 10
−6
of the recipient cells. Recombinant strains capable of polyhydroxyalkanoate synthesis from alkanes were constructed.
Description of a “Phoenix” Phenomenon in the Growth of
Campylobacter jejuni
at Temperatures Close to the Minimum for Growth
Authors: Kelly A. F. , Martínez-Rodriguez A. , Bovill R. A. , Mackey B. M.
Published: August 2003

When
Campylobacter jejuni
cultures that had been grown in broth at 39°C were subcultured into fresh medium at 30°C, there was a transient period of growth followed by a decline in viable-cell numbers before growth resumed once more. We propose that this complex behavior is the net effect of the growth of inoculum cells followed by a loss of viability due to oxidative stress and the subsequent emergence of a spontaneously arising mutant population that takes over the culture.
Analysis of the
argK-tox
Gene Cluster in Nontoxigenic Strains of
Pseudomonas syringae
pv. phaseolicola
Authors: González Ana Isabel , Pérez de la Vega Marcelino , Ruiz María Luisa , Polanco Carlos
Published: August 2003

The analysis of 46 isolates obtained directly from different and distant common bean fields from the northwestern part of Spain revealed that they do not produce phaseolotoxin. The isolates were classified as race 5, and their analysis revealed that they do not carry the
argK-tox
gene cluster involved in the biosynthesis of the phaseolotoxin.
Increased Exopolysaccharide Production in
Lactococcus lactis
due to Increased Levels of Expression of the NIZO B40
eps
Gene Cluster
Authors: Boels Ingeborg C. , van Kranenburg Richard , Kanning Marja W. , Chong Barrie Fong , de Vos Willem M. , Kleerebezem Michiel
Published: August 2003

Exopolysaccharides (EPS) play an important role in the rheology and texture of fermented food products. This is the first report demonstrating that homologous overexpression of a complete
eps
gene cluster in
Lactococcus lactis
leads to increased EPS production levels. A ninefold-elevated EPS plasmid copy number led to an almost threefold increase in the
eps
expression level, resulting in an almost fourfold increase in the NIZO B40 EPS production level. It was previously reported that increased EPS precursor levels did not influence NIZO B40 EPS production levels. However, the present results indicate that the maximal NIZO B40 EPS production level is limited by the activity level of the expression products of the
eps
gene cluster rather than by the level of EPS precursors.
Mannitol Is Required for Stress Tolerance inAspergillus nigerConidiospores
Authors: Ruijter George J. G. , Bax Maarten , Patel Hema , Flitter Simon J. , van de Vondervoort Peter J. I. , de Vries Ronald P. , vanKuyk Patricia A. , Visser Jaap
Published: August 2003

d-Mannitol is the predominant carbon compound in conidiospores of the filamentous fungusAspergillus nigerand makes up 10 to 15% of the dry weight. A number of physiological functions have been ascribed to mannitol, including serving as a reserve carbon source, as an antioxidant, and to store reducing power. In this study, we cloned and characterized theA. niger mpdAgene, which encodes mannitol 1-phosphate dehydrogenase (MPD), the first enzyme in the mannitol biosynthesis pathway. ThempdApromoter contains putative binding sites for the development-specific transcription factors BRLA and ABAA. Furthermore, increased expression ofmpdAin sporulating mycelium suggests that mannitol biosynthesis is, to a certain extent, developmentally regulated inA. niger. Inactivation ofmpdAabolished mannitol biosynthesis in growing mycelium and reduced the mannitol level in conidiospores to 30% that in the wild type, indicating that MPD and mannitol 1-phosphate phosphatase form the major metabolic pathway for mannitol biosynthesis inA. niger. The viability of spores after prolonged storage and germination kinetics were normal in anmpdAnull mutant, indicating that mannitol does not play an essential role as a reserve carbon source inA. nigerconidia. However, conidiospores of a ΔmpdAstrain were extremely sensitive to a variety of stress conditions, including high temperature, oxidative stress and, to a lesser extent, freezing and lyophilization. Since mannitol supplied in the medium during sporulation repaired this deficiency, mannitol appears to be essential for the protection ofA. nigerspores against cell damage under these stress conditions.
Diverged Binding Specificity of Rim101p, the
Candida albicans
Ortholog of PacC
Authors: Ramón Ana M. , Fonzi William A.
Published: August 2003

The biology of
Candida albicans
, including dimorphism and virulence, is significantly influenced by environmental pH. The response to ambient pH includes the pH-conditional expression of several genes, which is directly or indirectly regulated by Rim101p. Rim101p is homologous to PacC, a transcription factor that regulates pH-conditional gene expression in
Aspergillus nidulans
. PacC binds 5′-GCCARG-3′ sequences upstream of pH-responsive genes and either activates or represses transcription. The absence of
pacC
consensus binding sites upstream of
PHR1
, a
RIM101
-dependent, alkaline pH-induced gene of
C. albicans
, suggested either that
PHR1
is indirectly regulated by Rim101p or that the binding specificity of Rim101p is different. In vitro binding studies demonstrated that Rim101p strongly bound two regions upstream of
PHR1
that were only weakly bound by PacC. Deletion analysis and site-specific mutagenesis demonstrated that both sites were functionally significant, mutation of either site reduced
RIM101
-dependent induction, and expression was abolished in the double mutant. Furthermore, oligonucleotides containing these sites conferred pH-conditional expression when inserted upstream of a reporter gene. The consensus sequence of these sites, 5′-CCAAGAAA-3′, was identical to the binding recognition sequence identified by in vitro selection of Rim101p binding oligonucleotides from a random pool. The functional significance of this binding sequence was reinforced by its observed presence upstream of a number of newly identified pH-conditional genes. We conclude that Rim101p acts as a transcription factor and directly regulates pH-conditional gene expression but has a binding specificity different from that of PacC.
PAK
Paradox:
Paramecium
Appears To Have More K
+
-Channel Genes than Humans
Authors: Haynes W. John , Ling Kit-Yin , Saimi Yoshiro , Kung Ching
Published: August 2003

K
+
-selective ion channels (K
+
channels) have been found in bacteria, archaea, eucarya, and viruses. In
Paramecium
and other ciliates, K
+
currents play an essential role in cilia-based motility. We have retrieved and sequenced seven closely related
Paramecium
K
+
-channel gene (
PAK
) sequences by using previously reported fragments. An additional eight unique K
+
-channel sequences were retrieved from an indexed library recently used in a pilot genome sequencing project. Alignments of these protein translations indicate that while these 15 genes have diverged at different times, they all maintain many characteristics associated with just one subclass of metazoan K
+
channels (CNG/ERG type). Our results indicate that most of the genes are expressed, because all predicted frameshifts and several gaps in the homolog alignments contain
Paramecium
intron sequences deleted from reverse transcription-PCR products. Some of the variations in the 15 genomic nucleotide sequences involve an absence of introns, even between very closely related sequences, suggesting a potential occurrence of reverse transcription in the past. Extrapolation from the available genome sequence indicates that
Paramecium
harbors as many as several hundred of this one type of K
+
-channel gene. This quantity is far more numerous than those of K
+
-channel genes of all types known in any metazoan (e.g., ∼80 in humans, ∼30 in flies, and ∼15 in
Arabidopsis
). In an effort to understand this plurality, we discuss several possible reasons for their maintenance, including variations in expression levels in response to changes in the freshwater environment, like that seen with other major plasma membrane proteins in
Paramecium
.
Asexual Development Is Increased in
Neurospora crassa
cat
-
3
-Null Mutant Strains
Authors: Michán Shaday , Lledías Fernando , Hansberg Wilhelm
Published: August 2003

We use asexual development of
Neurospora crassa
as a model system with which to determine the causes of cell differentiation. Air exposure of a mycelial mat induces hyphal adhesion, and adherent hyphae grow aerial hyphae that, in turn, form conidia. Previous work indicated the development of a hyperoxidant state at the start of these morphogenetic transitions and a large increase in catalase activity during conidiation. Catalase 3 (CAT-3) increases at the end of exponential growth and is induced by different stress conditions. Here we analyzed the effects of
cat
-
3
-null strains on growth and asexual development. The lack of CAT-3 was not compensated by other catalases, even under oxidative stress conditions, and
cat
-

3
RIP

colonies were sensitive to H
2
O
2
, indicating that wild-type (Wt) resistance to external H
2
O
2
was due to CAT-3.
cat
-

3
RIP

colonies grown in the dark produced high levels of carotenes as a consequence of oxidative stress. Light exacerbated oxidative stress and further increased carotene synthesis. In the
cat
-

3
RIP

mutant strain, increased aeration in liquid cultures led to increased hyphal adhesion and protein oxidation. Compared to the Wt, the
cat
-

3
RIP

mutant strain produced six times more aerial hyphae and conidia in air-exposed mycelial mats, as a result of longer and more densely packed aerial hyphae. Protein oxidation in colonies was threefold higher and showed more aerial hyphae and conidia in mutant strains than did the Wt. Results indicate that oxidative stress due to lack of CAT-3 induces carotene synthesis, hyphal adhesion, and more aerial hyphae and conidia.
POS5
Gene of
Saccharomyces cerevisiae
Encodes a Mitochondrial NADH Kinase Required for Stability of Mitochondrial DNA
Authors: Strand Micheline K. , Stuart Gregory R. , Longley Matthew J. , Graziewicz Maria A. , Dominick Olivia C. , Copeland William C.
Published: August 2003

In a search for nuclear genes that affect mutagenesis of mitochondrial DNA in
Saccharomyces cerevisiae
, an ATP-NAD (NADH) kinase, encoded by
POS5
, that functions exclusively in mitochondria was identified. The
POS5
gene product was overproduced in
Escherichia coli
and purified without a mitochondrial targeting sequence. A direct biochemical assay demonstrated that the
POS5
gene product utilizes ATP to phosphorylate both NADH and NAD
+
, with a twofold preference for NADH. Disruption of
POS5
increased minus-one frameshift mutations in mitochondrial DNA 50-fold, as measured by the

arg8
m

reversion assay, with no increase in nuclear mutations. Also, a dramatic increase in petite colony formation and slow growth on glycerol or limited glucose were observed.
POS5
was previously described as a gene required for resistance to hydrogen peroxide. Consistent with a role in the mitochondrial response to oxidative stress, a
pos5
deletion exhibited a 28-fold increase in oxidative damage to mitochondrial proteins and hypersensitivity to exogenous copper. Furthermore, disruption of
POS5
induced mitochondrial biogenesis as a response to mitochondrial dysfunction. Thus, the
POS5
NADH kinase is required for mitochondrial DNA stability with a critical role in detoxification of reactive oxygen species. These results predict a role for NADH kinase in human mitochondrial diseases.
Antiholomorphic Involutions on Stein Manifolds
Authors: Hind Richard
Published: August 2003

We demonstrate the uniqueness of an antiholomorphic involution on a certain class of Stein manifolds. Examples are given to show why this uniqueness no longer holds without some topological assumptions.
Culling a Set of Points for Roundness or Cylindricity Evaluations
Authors: Devillers Olivier , Preparata Franco P.
Published: August 2003

Roundness and cylindricity evaluations are among the most important problems in computational metrology, and are based on sets of surface measurements (input data points). A recent approach to such evaluations is based on a linear-programming approach yielding a rapidly converging solution. Such a solution is determined by a fixed-size subset of a large input set. With the intent to simplify the main computational task, it appears desirable to cull from the input any point that cannot provably define the solution. In this note we present an analysis and an efficient solution to the problem of culling the input set. For input data points arranged in cross-sections under mild conditions of uniformity, this algorithm runs in linear time.
Effects of Shadowing on Drell–Yan Dilepton Production in High Energy Nuclear Collisions
Authors: Eskola K. J. , Kolhinen V. J. , Ruuskanen P. V. , Thews R. L.
Published: August 2003

We compute cross sections for the Drell–Yan process in nuclear collisions at next-to-leading order (NLO) in αs. The effects of shadowing on the normalization and on the mass and rapidity dependence of these cross sections are presented. An estimate of higher order corrections is obtained from next-to-next-to-leading order (NNLO) calculation of the rapidity-integrated mass distribution. Variations in these predictions resulting from choices of parton distributions sets are discussed. Numerical results for mass distributions at NLO are presented for RHIC and LHC energies, using appropriate rapidity intervals. The shadowing factors in the dilepton mass range 2 < M < 10 GeV are predicted to be substantial, typically 0.5 - 0.7 at LHC, 0.7 - 0.9 at RHIC, and approximately independent of the choice of parton distribution sets and the order of calculation.
Nanostructured Gold Thin Films: Young Modulus Measurement
Authors: Salvadori M. C. , Vaz A. R. , Melo L. L. , Cattani M.
Published: August 2003

We have uniformly coated the cantilever of an atomic force microscope (AFM) with gold thin films. These films are nanostructured with thickness going from 19 to 62 nm. The resonance frequencies of this cantilever have been measured, before and after the Au coatings. Taking into account these frequencies and the vibrating beam theory, we determined the Young modulus of the Au films, obtaining E2 = 69.1 ± 2.6 GPa , i.e. about 12% lower than the respective bulk elastic modulus.
Initial Growth of Co on Cu{001} Studied with LEED I(V)
Authors: Sainio J. , Alshamaileh E. , Lahtinen J. , Barnes C. J.
Published: August 2003

The initial growth of Co deposited at room temperature on Cu{001} was studied with low energy electron diffraction (LEED) and temperature-programmed desorption (TPD). Measured I(V) spectra were compared with calculated spectra from several model structures, including substitutionally disordered alloys. The averaged T-matrix approximation (ATA) was used to model the random alloy layers. According to the I(V) analysis, alloying occurs in the first stages of the growth. TPD of CO indicates that both large areas of Co and areas of a surface alloy are already present at the lowest coverage. Both methods show that a transition to layer-by-layer growth occurs as the coverage increases.
A RHEED Study of MBE Growth of ZnSe onGaAs(111)A-(2 × 2)
Authors: Gard F. S. , Riley J. D. , Leckey R. , Usher B. F.
Published: August 2003

ZnSe epilayers have been grown under various Se/Zn atomic flux ratios in the range of 0.22–2.45 at a substrate temperature of 350°C on Zn pre-exposed GaAs (111) A surfaces. Real time reflection high energy electron diffraction (RHEED) observations have shown a transition from a two-dimensional (2D) to a three-dimensional (3D) growth mode. The transition time depends directly upon the growth rate. A detailed discussion is presented to explore the cause of this change in the growth mode.
Intermetallic Formation in the Aluminum–Copper System
Authors: Hannech E. B. , Lamoudi N. , Benslim N. , Makhloufi B.
Published: August 2003

Intermetallic formation at 425°C in the aluminum–copper system has been studied by scanning electron microscopy using welded diffusion couples. Several Al–Cu phases predicted by the equilibrium phase diagram of the elements and voids taking place in the diffusion zone have been detected in the couples. The predominant phases were found to be Al 2 Cu 3 and the solid solution of Al in Cu, α. The growth of the intermetallic layer obeyed the parabolic law.
Thermal Decomposition Study of Dimethylaminoethanol on Si(100) by TPD and AES
Authors: Lim Sungwon , Yong Kijung
Published: August 2003

Thermal decomposition and desorption of dimethylaminoethanol [dmaeH, ( CH 3)2 NC 2 H 4 OH ] on Si(100) was studied using temperature-programmed desorption (TPD) and Auger electron spectroscopy (AES). During heating of the sample up to 1100 K, methyliminoacetaldehyde, ethylene, carbon monoxide and hydrogen molecule were desorbed as the main desorption products from dmaeH on Si(100). After TPD experiments, carbon and nitrogen were detected by AES, indicating that complete decomposition of dmaeH also proceeded on Si(100).
Photoelectron Microscopy Projects at SRRC
Authors: Wei D.-H. , Hsu Y.-J. , Klauser R. , Hong I.-H. , Yin G.-C. , Chuang T. J.
Published: August 2003

The combination of traditional surface-spectroscopic methods and microscopic imaging techniques is gaining popularity along with the advances of nanotechnology. Among the available techniques, scanning photoelectron microscopy (SPEM) and photoelectron emission microscopy (PEEM) are two methods recently developed at the Synchrotron Radiation Research Center (SRRC). The SPEM station uses a Fresnel zone-plate optics to focus the soft X-ray beam and form a microprobe. Photoelectrons emitted from the illuminated spot are used to perform micro-photoelectron spectroscopy (μ-PES) measurements or to image the sample. The PEEM station, on the other hand, collects secondary electrons emitted from the sample upon photon irradiation, and uses an all-electrostatic column to magnify the field of view defined by the objective lens. By stepping the photon energy, micro-X-ray absorption spectra (μ-XAS) can be extracted from a sequence of images after proper image processing.
Initial Stage of CaF2/Si(111) Epitaxy Investigated by Lateral/Atomic Force Microscopy
Authors: Wang C. R. , Müller B. H. , Hofmann K. R.
Published: August 2003

The initial stages of the high temperature (~ 700°C) MBE growth of CaF 2 on well-oriented Si(111) substrates have been studied by atomic force microscopy (AFM) and lateral force microscopy (LFM) in the atmosphere. At these temperatures CaF 2 molecules react with the silicon surface and form a CaF 1–Si interface layer. The CaF 1 layer covers the silicon surface completely before CaF 2 islands start to form, and it is stable in the atmospheric environment for some days. The subsequent growth on this interface layer results in multilayer CaF 2 islands (about 5 TL in height). The friction force experienced by the Si tip was found to be larger on the CaF 1 interface layer than that on the CaF 2 layer and allows a direct distinction between the CaF 1–Si interface layer and CaF 2. Two different types of islands are observed. One has a regular shape with a flat top surface; the other has an irregular shape and exhibits a 0.3–0.6-nm-high corrugation. We suppose that the formation of disturbed islands can be attributed to the dissociation of the CaF 1 interface at the growth temperature of 700°C. These results suggest that high growth temperatures (> 600°C) do not always result in the best CaF 2 film.
Fixation of Distal Radius Fractures Using AO Titanium Volar Distal Radius Plate
Authors: Lee H. C. , Wong Y. S. , Chan B. K. , Low C. O.
Published: August 2003

This study is to assess the effectiveness and outcome of the AO titanium volar distal radius plate (Synthes) in the treatment of peri-articular volar rim fractures of the distal radius. It was conducted on 22 patients with distal radius fractures who underwent open reduction, internal fixation using the AO titanium volar distal radius plate between July 1998 and December 1999 at the Changi General Hospital. The radiographs of the patients were analysed upon fracture union and assessment of wrist function was done using Gartland and Werley criteria. There were four extra-articular AO Type A2(1) and A3(3): the remaining 18 intra-articular fractures consisted of AO B3(2), AO C1(11), AO C2(2) and AO C3(3). The average follow-up period was 12.6 months (range 7–23). Radiological review showed bone healing in 21 patients (95.5%) and good articular congruity for all intra-articular fractures with less than 2 mm step-off. Three patients defaulted follow-up. Complications were few with one wound infection, one tendon rupture and three neuropraxia of the superficial radial nerve. Wrist function was excellent in three patients, good in 12 and fair in four. The AO titanium plate with its distal buttressing ability is an effective treatment modality in patients with distal radius fractures involving the peri-articular volar rim.
Dorsal and Palmar Material Properties of the Adult Human Flexor Profundus Tendon in Zone II
Authors: Soejima Osamu , Diao Edward , Lotz Jeffrey C. , Hariharan Jayaram S. , Naito Masatoshi
Published: August 2003

Nineteen fresh frozen adult human flexor digitorum profundus (FDP) tendons in Zone II were studied to compare the differences in material properties between the dorsal (dFDP) and palmar (pFDP) side of each tendon biomechanically, biochemically and histologically. We have found that tissue from the dorsal side of each flexor tendon has (1) greater strength; (2) less collagen crosslinking (hydroxypyridinium); and (3) a larger single bundle cross-sectional area than tissue from the palmar side of the same tendon. These data clearly demonstrate that the dorsal and palmar sides of the adult human (FDP) tendon in Zone II differ materially. These differences suggest that there may be biomechanical advantages in placing core sutures dorsally when repairing flexor tendons, a technique that we have previously described.
A Case of Pseudarthrosis of the Capitate
Authors: Morisawa Yasushi , Ikegami Hiroyasu , Takayama Shinichiro , Toyama Yoshiaki
Published: August 2003

Pseudarthrosis of the capitate bone is extremely rare. In this case, the injury and pseudarthrosis was so old, the bone with a nutrient vessel was grafted, and bone union and excellent results are obtained.