bluuebunny/crossref_metadata_2025 huggingface dataset:
Arthropod Abundance, Canopy Structure, and Microclimate in a Bornean Lowland Tropical Rain Forest1
Authors: Dial Roman J. , Ellwood Martin D. F. , Turner Edward C. , Foster William A.
Published: June 2006

This study applies a novel, vertically stratified fogging protocol to document arthropod abundance, density, and biomass across a vertical gradient in a primary, lowland dipterocarp forest canopy in Borneo. We fogged arthropods at 5 m vertical intervals and 20 m horizontal intervals along six full‐canopy transects and measured leaf surface areas along the same transects. The results show that arthropod biomass in the aboveground regions was 23.6 kg/ha, the abundance was 23.9 million individuals/ha, and the density on leaf surfaces was 280 individuals/m2 leaf area. All three numbers are five to ten times higher than estimated by previous surveys of tropical lowland rain forest canopies using mass‐collection techniques. Arthropod abundance and biomass were analyzed in relation to canopy structure, composition, vapor pressure deficit (VPD), photosynthetic photon flux density (PPFD), and height. Using stepwise regression we found that 13 of 14 arthropod groups had significant positive relationships with one‐sided leaf area, 11 had significant negative relationships with VPD, 3 had significant relationships with height, and none showed positive relationships with light. Classifying the 14 taxa based on their responses to leaf area and VPD created three groups that corresponded roughly to the biology of these taxa. This study suggests that the biomass and abundance, and perhaps therefore—by extrapolation—the biodiversity, of tropical canopy arthropods may be very much higher than previously estimated.
Preliminary Evidence of the Importance of ENSO in Modifying Food Availability for White‐tailed Deer in a Mexican Tropical Dry Forest1
Authors: Mandujano Salvador
Published: June 2006

The influence of El Niño/Southern Oscillation (ENSO) on rainfall and its possible effect on availability of food for white‐tailed deer (Odocoileus virginianus) in a tropical dry forest in the Pacific coast of Mexico was studied. From 1977 to 2003 there were three significant El Niño and La Niña events. During El Niño years rainfall decreased during the wet season ( June to October) and increased during the dry season (November to May), with the opposite effect during La Niña years. Plant diversity was monitored in permanent plots during the wet and dry seasons of 1989–1993. The results provide evidence that ENSO events affect deer food availability, particularly in the dry season.
PopF1 and PopF2, Two Proteins Secreted by the Type III Protein Secretion System of
Ralstonia solanacearum
, Are Translocators Belonging to the HrpF/NopX Family
Authors: Meyer Damien , Cunnac Sébastien , Guéneron Mareva , Declercq Céline , Van Gijsegem Frédérique , Lauber Emmanuelle , Boucher Christian , Arlat Matthieu
Published: June 2006

Ralstonia solanacearum
GMI1000 is a gram-negative plant pathogen which contains an
hrp
gene cluster which codes for a type III protein secretion system (TTSS). We identified two novel Hrp-secreted proteins, called PopF1 and PopF2, which display similarity to one another and to putative TTSS translocators, HrpF and NopX, from
Xanthomonas
spp. and rhizobia, respectively. They also show similarities with TTSS translocators of the YopB family from animal-pathogenic bacteria. Both
popF1
and
popF2
belong to the HrpB regulon and are required for the interaction with plants, but PopF1 seems to play a more important role in virulence and hypersensitive response (HR) elicitation than PopF2 under our experimental conditions. PopF1 and PopF2 are not necessary for the secretion of effector proteins, but they are required for the translocation of AvrA avirulence protein into tobacco cells. We conclude that PopF1 and PopF2 are type III translocators belonging to the HrpF/NopX family. The
hrpF
gene of
Xanthomonas campestris
pv.
campestris
partially restored HR-inducing ability to
popF1 popF2
mutants of
R. solanacearum
, suggesting that translocators of
R. solanacearum
and
Xanthomonas
are functionally conserved. Finally,
R. solanacearum
strain UW551, which does not belong to the same phylotype as GMI1000, also possesses two putative translocator proteins. However, although one of these proteins is clearly related to PopF1 and PopF2, the other seems to be different and related to NopX proteins, thus showing that translocators might be variable in
R. solanacearum
.
Uracil Salvage Pathway in
Lactobacillus plantarum
: Transcription and Genetic Studies
Authors: Arsène-Ploetze Florence , Nicoloff Hervé , Kammerer Benoît , Martinussen Jan , Bringel Françoise
Published: June 2006

The uracil salvage pathway in
Lactobacillus plantarum
was demonstrated to be dependent on the
upp-pyrP
gene cluster. PyrP was the only high-affinity uracil transporter since a
pyrP
mutant no longer incorporated low concentrations of radioactively labeled uracil and had increased resistance to the toxic uracil analogue 5-fluorouracil. The
upp
gene encoded a uracil phosphoribosyltransferase (UPRT) enzyme catalyzing the conversion of uracil and 5-phosphoribosyl-α-1-pyrophosphate to UMP and pyrophosphate. Analysis of mutants revealed that UPRT is a major cell supplier of UMP synthesized from uracil provided by preformed nucleic acid degradation. In a mutant selection study, seven independent
upp
mutants were isolated and all were found to excrete low amounts of pyrimidines to the growth medium. Pyrimidine-dependent transcription regulation of the biosynthetic pyrimidine
pyrR1-B-C-Aa1-Ab1-D-F-E
operon was impaired in the
upp
mutants. Despite the fact that
upp
and
pyrP
are positioned next to each other on the chromosome, they are not cotranscribed. Whereas
pyrP
is expressed as a monocistronic message, the
upp
gene is part of the
lp
_
2376-glyA-upp
operon. The
lp
_
2376
gene encodes a putative protein that belongs to the conserved protein family of translation modulators such as Sua5, YciO, and YrdC. The
glyA
gene encodes a putative hydroxymethyltransferase involved in C
1
unit charging of tetrahydrofolate, which is required in the biosynthesis of thymidylate, pantothenate, and purines. Unlike
upp
transcription,
pyrP
transcription is regulated by exogenous pyrimidine availability, most likely by the same mechanism of transcription attenuation as that of the
pyr
operon.
The Conjugative Transposon Tn
5397
Has a Strong Preference for Integration into Its
Clostridium difficile
Target Site
Authors: Wang Hongmei , Smith Margaret C. M. , Mullany Peter
Published: June 2006

Tn
5397
is a conjugative transposon, originally isolated from
Clostridium difficile
. The Tn
5397
transposase TndX is related to the phage-encoded serine integrases and the
Clostridium perfringens
Tn
4451
transposase TnpX. TndX is required for the insertion and excision of the transposon. Tn
5397
inserts at one locus,

attB
Cd

, in
C. difficile
but at multiple sites in
Bacillus subtilis
. Apart from a conserved 5′ GA dinucleotide at the recombination site, there appears to be little sequence conservation between the known target sites. To test the target site preference of Tn
5397
,

attB
Cd

was introduced into the
B. subtilis
genome. When Tn
5397
was transferred into this strain, 100% of the 50 independent transconjugants tested had Tn
5397
inserted into

attB
Cd

. This experiment was repeated using a 50-bp

attB
Cd

with no loss of target preference. The mutation of the 5′ GA to 5′ TC in the

attB
Cd

target site caused a switch in the polarity of insertion of Tn
5397
, which is consistent with this dinucleotide being at the crossover site and in keeping with the mechanism of other serine recombinases. Tn
5397
could also transpose into 50-bp sequences encoding the end joints
attL
and
attR
but, surprisingly, could not recombine into the circular joint of Tn
5397
,
attTn
. Purified TndX was shown to bind specifically to 50-bp

attB
Cd

,
attL
,
attR
,
attTn
, and

attB
Bs

3
with relative binding affinities
attTn
≈
attR
>
attL
>

attB
Cd

>

attB
Bs

3
. We conclude that TndX has a strong preference for

attB
Cd

over other potential recombination sites in the
B. subtilis
genome and therefore behaves as a site-specific recombinase.
A Pair of Iron-Responsive Genes Encoding Protein Kinases with a Ser/Thr Kinase Domain and a His Kinase Domain Are Regulated by NtcA in the CyanobacteriumAnabaenasp. Strain PCC 7120
Authors: Cheng Yong , Li Jian-Hong , Shi Lei , Wang Li , Latifi Amel , Zhang Cheng-Cai
Published: June 2006

The filamentous cyanobacteriumAnabaenasp. strain PCC 7120 can fix N2when combined nitrogen is not available in the growth medium. It has a family of 13 genes encoding proteins with both a Ser/Thr kinase domain and a His kinase domain. The function of these enzymes is unknown. Two of them are encoded bypkn41(alr0709) andpkn42(alr0710). These two genes are separated by only 72 bp on the chromosome, and our results indicate that they are cotranscribed. The expression ofpkn41andpkn42is induced by iron deprivation irrespective of the nature of the nitrogen source. Mutants inactivating eitherpkn41,pkn42, or both grow similarly to the wild type under normal conditions, but their growth is impaired either in the presence of an iron chelator or under conditions of nitrogen fixation and iron limitation, two situations where the demand for iron is particularly strong. Consistent with these results, these mutants display lower iron content than the wild type and a higher level of expression fornifJ1andnifJ2, which encode pyruvate:ferredoxin oxidoreductases. BothnifJ1andnifJ2are known to be induced by iron limitation. NtcA, a global regulatory factor for different metabolic pathways, binds to the putative promoter region ofpkn41, and the induction ofpkn41in response to iron limitation no longer occurs in anntcAmutant. Our results suggest thatntcAnot only regulates the expression of genes involved in nitrogen and carbon metabolism but also coordinates iron acquisition and nitrogen metabolism by activating the expression ofpkn41andpkn42.
Effect of some environmental parameters on fermentative hydrogen production by Enterobacter cloacae DM11
Authors: Nath Kaushik , Kumar Anish , Das Debabrata
Published: June 2006

Fermentative hydrogen production was carried out by Enterobacter cloacae DM11, using glucose as the substrate. The effects of initial substrate concentration, initial medium pH, and temperature were investigated. Results showed that at an initial glucose concentration of 1.0% (m/v), the molar yield of hydrogen was 3.31 mol (mol glucose)–1. However, at higher initial glucose concentration, both the rate and cumulative volume of hydrogen production decreased. The pH of 6.5 ± 0.2 at a temperature of 37 °C was found most suitable with respect to maximum rate of production of hydrogen in batch fermentation. Activation enthalpies of fermentation and that of thermal deactivation of the present process were estimated following a modified Arrhenius equation. The values were 47.34 and 118.67 kJ mol–1 K–1, respectively. The effect of the addition of Fe2+ on hydrogen production was also studied. It revealed that the presence of iron (Fe2+) in the media up to a concentration of 20 mg L–1 had a marginal enhancing effect on total hydrogen production. A simple model developed from the modified Gompertz equation was applied to estimate the hydrogen production potential, production rate, and lag-phase time in a batch process, based on the cumulative hydrogen production curves, using the software program Curve Expert 1.3. Key words: hydrogen, Enterobacter cloacae DM11, fermentation, glucose, H2 yield.
Sodium Paradoxically Reduces the Gastropressor Response in Patients With Orthostatic Hypotension
Authors: Raj Satish R. , Biaggioni Italo , Black Bonnie K. , Rali Aniket , Jordan Jens , Taneja Indu , Harris Paul A. , Robertson David
Published: June 2006

Orthostatic hypotension (OH) can cause syncope that is difficult to treat. We have found that 473 mL (16 oz) of water can increase systolic blood pressure (SBP) by >30 mm Hg in many OH patients (the gastropressor response). OH patients are routinely advised to increase their sodium intake to augment their blood volume. We tested the hypothesis that the ingestion of salt with water would increase the magnitude of the acute pressor response compared with water alone in patients with OH. Patients with OH (n=9; female=5; 65±3 years) underwent a randomized crossover trial of drinking water (H
2
O) and salt water (NaCl-H
2
O). Noninvasive heart rate and BP were measured with the patient seated for ≥60 minutes after ingestion. The area under the curve for SBP was greater with H
2
O than NaCl-H
2
O for the 30 minutes (714±388 mm Hg×min versus 364±369 mm Hg×min;
P
=0.002) and 60 minutes (1454±827 mm Hg×min versus 812±734 mm Hg×min;
P
=0.048) after ingestion. The increase in SBP with H
2
O was greater than with NaCl-H
2
O at 30 minutes (37±6 versus 18±5 mm Hg;
P
=0.006) but not at 60 minutes (17±6 versus 10±6 mm Hg;
P
=0.4). Norepinephrine increased after H
2
O (
P
=0.018) but not after NaCl-H
2
O (
P
=0.195). Both oral water and salt water increase BP in patients with OH. Instead of augmenting the gastropressor response, the additional salt paradoxically attenuates the pressor response to water. These data suggest a potentially important role for gastrointestinal osmolality in the activation of the sympathetic nervous system leading to cardiovascular reflexes responsible for the gastropressor response.
Oxidative Stress Mediates the Stimulation of Sympathetic Nerve Activity in the Phenol Renal Injury Model of Hypertension
Authors: Ye Shaohua , Zhong Huiquin , Campese Vito M.
Published: June 2006

Renal injury caused by the injection of phenol in the lower pole of one kidney increases blood pressure (BP), norepinephrine secretion from the posterior hypothalamic nuclei (PH), and renal sympathetic nerve activity in the rat. Renal denervation prevents these effects of phenol. We have also demonstrated that noradrenergic traffic in the brain is modulated by NO and interleukin-1β. In this study, we tested the hypothesis that the increase in sympathetic nervous system (SNS) activity in the phenol renal injury model is because of activation of reactive oxygen species. To this end, first we examined the abundance of several components of reduced nicotinamide-adenine dinucleotide phosphate oxidase (identified as the major source of reactive oxygen species), including gp91phox/Nox2, p22phox, p47phox, and Nox3 using real-time PCR. Second, we evaluated the effects of 2 superoxide dismutase mimetic, tempol (4-hydroxy-2,2,6,6-tetramethyl piperidinoxyl), and superoxide dismutase-polyethylene glycol on central and peripheral SNS activation caused by intrarenal phenol injection. Intrarenal injection of phenol raised BP, NE secretion from the PH, renal sympathetic nerve activity, and the abundance of reduced nicotinamide-adenine dinucleotide phosphate and reduced the abundance of interleukin-1β and neural-NO synthase mRNA in the PH, paraventricular nuclei, and locus coeruleus compared with control rats. When tempol or superoxide dismutase-polyethylene glycol were infused in the lateral ventricle before phenol, the effects of phenol on BP and SNS activity were abolished. The studies suggest that central activation of the SNS in the phenol-renal injury model is mediated by increased reactive oxygen species in brain nuclei involved in the noradrenergic control of BP.
Trends in the Incidence of Type 2 Diabetes Mellitus From the 1970s to the 1990s
Authors: Fox Caroline S. , Pencina Michael J. , Meigs James B. , Vasan Ramachandran S. , Levitzky Yamini S. , D’Agostino Ralph B.
Published: June 2006

Background—

Recent studies indicate that the prevalence of type 2 diabetes mellitus is increasing in the United States; less is known about trends in the incidence of type 2 diabetes mellitus.

Methods and Results—

Participants free of diabetes mellitus (n=3104; mean age 47 years; 1587 women) from the Framingham Offspring Study who attended a routine examination in the 1970s, 1980s, or 1990s were followed up for the 8-year incidence of diabetes mellitus. Diabetes was defined as a fasting plasma glucose ≥7.0 mmol/L or treatment with either insulin or a hypoglycemic agent. Pooled logistic regression was used to compare diabetes incidence across decades for participants between 40 and 55 years of age in each decade. The age-adjusted 8-year incidence rate of diabetes was 2.0%, 3.0%, and 3.7% among women and 2.7%, 3.6%, and 5.8% among men in the 1970s, 1980s, and 1990s, respectively. Compared with the 1970s, the age- and sex-adjusted odds ratio (OR) for diabetes was 1.40 (95% confidence interval [CI], 0.89 to 2.22) in the 1980s and 2.05 (95% CI, 1.33 to 3.14) in the 1990s (
P
for trend=0.0006). Among women, the OR was 1.50 (95% CI, 0.75 to 2.98) in the 1980s and 1.84 (95% CI, 0.95 to 3.55) in the 1990s (
P
for trend=0.07) compared with the 1970s, whereas among men, the OR was 1.33 (95% CI, 0.72 to 2.47) in the 1980s and 2.21 (95% CI, 1.25 to 3.90) in the 1990s (
P
for trend=0.003). Most of the increase in absolute incidence of diabetes occurred in individuals with body mass index ≥30 kg/m
2
(
P
for trend=0.03).

Conclusions—

In the present community-based sample of middle-aged adults, we observed a doubling in the incidence of type 2 diabetes over the last 30 years. Careful surveillance of changes in diabetes incidence may be necessary if current trends of excess adiposity continue.
In silico identification of putative promoter motifs of White Spot Syndrome Virus
Authors: Marks Hendrik , Ren Xin-Ying , Sandbrink Hans , van Hulten Mariëlle CW , Vlak Just M
Published: June 2006

Background

White Spot Syndrome Virus, a member of the virus family Nimaviridae, is a large dsDNA virus infecting shrimp and other crustacean species. Although limited information is available on the mode of transcription, previous data suggest that WSSV gene expression occurs in a coordinated and cascaded fashion. To search in silico for conserved promoter motifs (i) the abundance of all 4 through 8 nucleotide motifs in the upstream sequences of WSSV genes relative to the complete genome was determined, and (ii) a MEME search was performed in the upstream sequences of either early or late WSSV genes, as assigned by microarray analysis. Both methods were validated by alignments of empirically determined 5' ends of various WSSV mRNAs.

Results

The collective information shows that the upstream region of early WSSV genes, containing a TATA box and an initiator, is similar to Drosophila RNA polymerase II core promoter sequences, suggesting utilization of the cellular transcription machinery for generating early transcripts. The alignment of the 5' ends of known well-established late genes, including all major structural protein genes, identified a degenerate motif (ATNAC) which could be involved in WSSV late transcription. For these genes, only one contained a functional TATA box. However, almost half of the WSSV late genes, as previously assigned by microarray analysis, did contain a TATA box in their upstream region.

Conclusion

The data may suggest the presence of two separate classes of late WSSV genes, one exploiting the cellular RNA polymerase II system for mRNA synthesis and the other generating messengers by a new virus-induced transcription mechanism.
Mitochondrial phylogeny and phylogeography of East African squeaker catfishes (Siluriformes: Synodontis)
Authors: Koblmüller Stephan , Sturmbauer Christian , Verheyen Erik , Meyer Axel , Salzburger Walter
Published: June 2006

Background

Squeaker catfishes (Pisces, Mochokidae,Synodontis) are widely distributed throughout Africa and inhabit a biogeographic range similar to that of the exceptionally diverse cichlid fishes, including the three East African Great Lakes and their surrounding rivers. Since squeaker catfishes also prefer the same types of habitats as many of the cichlid species, we hypothesized that the East AfricanSynodontisspecies provide an excellent model group for comparative evolutionary and phylogeographic analyses.

Results

Our analyses reveal the existence of six major lineages ofSynodontisin East Africa that diversified about 20 MYA from a Central and/or West African ancestor. The six lineages show a clear geographic patterning. Two lineages are endemic to Lake Tanganyika (plus one non-endemic representative), and these are the only twoSynodontislineages that diversified further into a small array of species. One of these species is the cuckoo catfish (S. multipunctatus), a unique brood parasite of mouthbrooding haplochromine cichlids, which seems to have evolved in parallel with the radiation of its cichlid host lineage, the Tropheini. We also detect an accelerated rate of molecular evolution inS. multipunctatus, which might be the consequence of co-evolutionary dynamics.

Conclusion

We conclude that the ancestral lineage of today's East African squeaker catfish fauna has colonized the area before the Great Lakes have formed. This ancestor diversified rapidly into at least six lineages that inhabit lakes and rivers in East Africa. Lake Tanganyika is the only lake harboring a small species flock of squeaker catfishes.
The normal human chondro-osseous junctional region: evidence for contact of uncalcified cartilage with subchondral bone and marrow spaces
Authors: Lyons Tim J , McClure Sheena F , Stoddart Robert W , McClure John
Published: June 2006

Background

The chondro-osseous junctional region of diarthrodial joints is peculiarly complex and may be considered to consist of the deepest layer of non-calcified cartilage, the tidemark, the layer of calcified cartilage, a thin cement line (between the calcified cartilage and the subchondral bone) and the subchondral bone. A detailed knowledge of the structure, function and pathophysiology of the normal chondro-osseous junction is essential for an understanding of the pathogenesis of osteoarthrosis.

Methods

Full thickness samples from human knee joints were processed and embedded in paraffin wax. One hundred serial sections (10 μm thick) were taken from the chondro-osseous junctional region of a block from the medial tibial plateau of a normal joint. They were stained with haematoxylin and eosin and photographed. For a simple physical reconstruction images of each 10th sequential tissue section were printed and the areas of the photomicrographs containing the chondro-osseous junctional region were cut out and then overlaid so as to create a three-dimensional (3D) model of this region. A 3D reconstruction was also made using computer modelling.

Results

Histochemical staining revealed some instances where prolongations of uncalcified cartilage, delineated by the tidemark, dipped into the calcified cartilage and, in places, abutted onto subchondral bone and marrow spaces. Small areas of uncalcified cartilage containing chondrocytes (virtual islands) were seen, in two-dimensional (2D) sections, to be apparently entombed in calcified matrix. The simple physical 3D reconstruction confirmed that these prolongations of uncalcified cartilage were continuous with the cartilage of zone IV and demonstrated that the virtual islands of uncalcified cartilage were cross-sections of these prolongations. The computer-generated 3D reconstructions clearly demonstrated that the uncalcified prolongations ran through the calcified cartilage to touch bone and marrow spaces and confirmed that the apparent entombment of chondrocytes was a 2D artefact.

Conclusion

This study demonstrates that the chondro-osseous junctional region is more complex than previously described. The tidemark is a clearly defined boundary delineating uncalcified from calcified cartilage. It is not a straight line across a joint, but a complex three-dimensional structure that follows uncalcified cartilage prolongations dipping down through the calcified cartilage to abut onto subjacent bone or marrow spaces.
Active and passive displacement of transmembrane domains both occur during opsin biogenesis at the Sec61 translocon
Authors: Ismail Nurzian , Crawshaw Samuel G. , High Stephen
Published: June 2006

We used a site-specific crosslinking approach to study the membrane integration of the polytopic protein opsin at the endoplasmic reticulum. We show that transmembrane domain 1 occupies two distinct Sec61-based environments during its integration. However, transmembrane domains 2 and 3 exit the Sec61 translocon more rapidly in a process that suggests a displacement model for their integration where the biosynthesis of one transmembrane domain would facilitate the exit of another. In order to investigate this hypothesis further, we studied the integration of the first and third transmembrane domains of opsin in the absence of any additional C-terminal transmembrane domains. In the case of transmembrane domain 1, we found that its lateral exit from the translocon is clearly dependent upon the synthesis of subsequent transmembrane domains. By contrast, the lateral exit of the third transmembrane domain occurred independently of any such requirement. Thus, even within a single polypeptide chain, distinct transmembrane domains display different requirements for their integration through the endoplasmic reticulum translocon, and the displacement of one transmembrane domain by another is not a global requirement for membrane integration.
The connection between splicing and cancer
Authors: Srebrow Anabella , Kornblihtt Alberto R.
Published: June 2006

Alternative splicing is a crucial mechanism for generating protein diversity. Different splice variants of a given protein can display different and even antagonistic biological functions. Therefore, appropriate control of their synthesis is required to assure the complex orchestration of cellular processes within multicellular organisms. Mutations in cis-acting splicing elements or changes in the activity of constitutive or alternative splicing could have a profound regulatory proteins that compromise the accuracy of either impact on human pathogenesis, in particular in tumor development and progression. Mutations in splicing elements, for example, have been found in genes such as LKB1, KIT, CDH17, KLF6 and BRCA1, and changes in trans-acting regulators can affect the expression of genes such as Ron, RAC1 and CD44.
The effect of myoglobin concentration on aerobic dive limit in a Weddell seal
Authors: Wright T. J. , Davis R. W.
Published: June 2006

One physiological adaptation for prolonged dive duration in marine mammals is an elevated myoglobin (Mb) concentration in skeletal muscle. To determine the influence of Mb concentration on the aerobic dive limit (ADL), we modified a previously published model that simulated aerobic dives in a Weddell seal(Leptonychotes weddellii) and ran it for four Mb concentrations: 5,27, 54 and 108 g Mb kg–1 muscle representing 7%, 50%, 100%and 200%, respectively, of the normal Mb concentration in Weddell seal skeletal muscle. The model was run at increasing levels of muscular exertion and under postabsorptive and postprandial conditions to determine their effect on ADL. For each set of conditions, the model was also run at different levels of cardiac output (i.e. the dive response was varied) to determine the level of convective oxygen transport that optimized the ADL. In a postabsorptive state at a routine level of muscular exertion for a diving Weddell seal, a decrease in Mb concentration to 7% of normal caused a 39% decrease in the ADL(18 min to 11 min), while doubling the Mb concentration increased the ADL by 30% (18 min to 24 min). Under postprandial conditions at a routine level of muscular exertion, doubling the Mb concentration did not increase the ADL (12 min). The convective oxygen transport needed to meet the metabolic demands(Heat Increment of Feeding, HIF) of the splanchnic organs during digestion and assimilation required a cardiac output that was not optimal for the efficient use of muscle oxygen stores. This resulted in an over perfusion of the muscles and incomplete use of myoglobin-bound oxygen. As a result, the postprandial ADL was limited by the amount of oxygen stored in the blood, and increasing the Mb concentration had no effect on the ADL. We hypothesize that myoglobin concentration is optimized for the type and duration of dives routinely made by Weddell seals, and that a further increase may not increase the ADL for most free-ranging dives.
Valence Isomerism between Sterically Protected Methylenephosphine P-Sulfide and 1,2-Thiaphosphirane
Authors: Toyota Kozo , Takahashi Hiroaki , Shimura Kazuho , Yoshifuji Masaaki
Published: June 2006

Reaction of (diphenylmethylene)(2,4,6-tri-t-butylphenyl)phosphine with elemental sulfur afforded 3,3-diphenyl-2-(2,4,6-tri-t-butylphenyl)-1,2-thiaphosphirane 2-sulfide via methylenephosphine P-sulfide. Desulfurization reaction of the thiaphosphirane 2-sulfide with tris(dimethylamino)phosphine gave 3,3-diphenyl-2-(2,4,6-tri-t-butylphenyl)-1,2-thiaphosphirane. Valence isomerization occurred between the methylenephosphine P-sulfide and the thiaphosphirane by heat or by photo-irradiation. The structures of the methylenephosphine, the methylenephosphine P-sulfide, and the thiaphosphirane were analyzed by X-ray crystallography.
Hydrogenation on Supported Lanthanide–Palladium Bimetallic Catalysts: Appearance of Considerable Hydrogen Uptake
Authors: Imamura Hayao , Igawa Koji , Sakata Yoshihisa , Tsuchiya Susumu
Published: June 2006

Upon introducing of lanthanide metals (Ln : Eu or Yb) onto a Pd surface by the reaction of Pd/SiO2 with Eu or Yb metal dissolved in liquid ammonia, the ability of considerable hydrogen uptake by the catalyst appeared during the hydrogenation reaction. Hydrogenation over supported lanthanide–palladium bimetallic catalysts was studied at 173—213 K, especially concerning the effects of the reactants, support materials, Pd particle sizes, and dispersion on the hydrogenation behavior with the hydrogen uptake. For the hydrogenation of ethene, propene, butene or butadiene, considerable hydrogen uptake occurred preferentially, followed by hydrogenation using the hydrogen taken up the catalyst. The hydrogenation occurred by a rate-limited hydrogen uptake process. In marked contrast to olefin and butadiene, no hydrogen uptake was observed for the hydrogenation of acetylene, indicating the progress of the reaction by a different mechanism. The support materials (SiO2, Al2O3, ZrO2, MgO, and TiO2), Pd particle sizes and Pd dispersion in Pd/support were important factors in determining the hydrogen uptake by supported Ln–Pd catalysts and the resulting hydrogenation behavior.
Metalation of Water-Soluble Octabromoporphyrin with Lithium(I), Cadmium(II), and Mercury(II)
Authors: Tabata Masaaki , Nishimoto Jun , Ogata Akiko , Kusano Tohru , Nahar Nurun
Published: June 2006

A water-soluble porphyrin, 2,3,7,8,12,13,17,18-octabromo-5,10,15,20-tetrakis(4-sulfonatophenyl)porphyrin (H2obtpps4−; H2P4−) was synthesized and the equilibrium constants have been determined for the reaction of H2obtpps4− with lithium(I), cadmium(II), and mercury(II) at 25 °C in I = 0.1 mol dm−3 (NaNO3). The protonation constants of H2obtpps4− were found to be 104.83 ± 0.04 mol−1 dm3, 101.96 ± 0.06 mol−1 dm3, and 10−10.02 ± 0.02 mol dm−3 for K1 = [H3P3−][H+]−1[H2P4−]−1, K2 = [H4P2−][H+]−1[H3P3−]−1, and K−1 = [HP5−][H+][H2P4−]−1, respectively. The porphyrin reacted with lithium(I) in alkaline aqueous solution to form LiP5−, of which formation constant was 10−18.81 ± 0.02 mol dm−3 for KLiP = [LiP5−][H+]2[Li+]−1[H2P4−]−1. Sodium and potassium ions did not form their complexes under the same experimental conditions. The equilibrium constants for the formation of cadmium(II) and mercury(II) porphyrins defined by KMP = [MP4−][H+]2[M2+]−1[H2P4−]−1, M = Cd2+; Hg2+, were 10−8.60 ± 0.13 mol dm−3 and 100.12 ± 0.06 mol dm−3 for KCdP and KHgP, respectively. Mercury(II) also forms homodinuclear porphyrin, Hg2P, and the value was 103.57 ± 0.03 mol−1 dm3 for KHg2P = [Hg2P2−][Hg2+]−1[HgP4−]−1. The octabromo groups lower the basicity of the porphyrin, which results in the formation of lithium(I) porphyrin.
Oxidation of Organic Compounds with Tetrabutylammonium Periodate in the Presence of Lewis Acids in Aprotic Organic Solvents
Authors: Firouzabadi Habib , Sardarian Alireza , Badparva Hasan
Published: June 2006

Tetrabutylammonium periodate is able to oxidize alcohols to their carbonyl compounds, α-hydroxy ketones to α-diketones, α-hydroxy carboxylic acids to the carbonyl compounds (accompanied with decarboxylation), thiols to disulfides, thioethers to sulfoxides in CHCl3 and CH3CN in the presence of AlCl3 and BF3·Et2O as catalysts.
Flotation of Uranium from Seawater with Phosphate Esters of C-Undecylcalix[4]resorcinarene
Authors: Koide Yoshifumi , Terasaki Hiroyuki , Sato Hirotaka , Shosenji Hideto , Yamada Kimiho
Published: June 2006

Table-type chelating surfactants ([4]ArmX-R12, mX means the number of phosphates (P), carboxylic acid (Ac), and hydroxamic acid (Hx), respectively) have been derived from the calix[4]resorcinarene bearing tetradodecyl side chains ([4]Ar-R12), and applied to a collector of uranium flotation. The surface tension of the aqueous solution was 35 mN m−1 for [4]Ar5.6P-R6 (Rn means the alkyl chain length), 52 mN m−1 for [4]Ar5.9P-R12, 42 mN m−1 for [4]Ar8.0Ac-R12, and 48 mN m−1 for [4]Ar5.1Hx-R12. They formed UO2 complexes and floated the UO22+ from an aqueous solution by air-bubbling. Furthermore, [4]Ar5.9P-R12 and [4]Ar6.3P-R12 had competence to float the uranium from seawater. A trace amount of uranium in 450 cm3 of seawater was floated at 68—94% using 1—10 mg of [4]Ar5.9P-R12 or [4]Ar6.3P-R12. On the other hand, [4]Ar5.1Hx-R12 and [4]Ar8.0Ac-R12 brought about lower floatabilities. [4]ArmP-R12 could be recycled several times by dissolving the scum (uranium complex) in 5 mol dm−3 H2SO4.
Prosthodontic Self-treatment With Acrylic Resin Super Glue: A Case Report
Authors: Winkler Sheldon , Wood Robert , Facchiano Anne M. , Boberick Kenneth G. , Patel Amita R.
Published: June 2006

A case history is presented of a patient who fabricated 3 prostheses from autopolymerizing acrylic resin intended for fingernail augmentation and then cemented them into her mouth with super glue. Patients must be warned not to attempt self-treatment for esthetics with self-fabricated prostheses because severe adverse and irreversible hard and soft tissue reactions may occur.
Permissive Influence of Stress in the Expression of a U-Shaped Relationship between Serum Corticosterone Levels and Spatial Memory Errors in Rats
Authors: Park Collin R. , Campbell Adam M. , Woodson James C. , Smith Taro P. , Fleshner Monika , Diamond David M.
Published: June 2006

The relationship between glucocorticoids (GCs) and memory is complex, in that memory impairments can occur in response to manipulations that either increase or decrease GC levels. We investigated this issue by assessing the relationship between serum corticosterone (the primary rodent GC) and memory in rats trained in the radial arm water maze, a hippocampus-dependent spatial memory task. Each day, rats learned a new location of the hidden escape platform and then 30 min later their memory of the location of the platform was tested. Under control conditions, well-trained rats had excellent spatial memory and moderately elevated corticosterone levels (∼26 μg/dl versus a baseline of ∼2 μg/dl). Their memory was impaired when corticosterone levels were either reduced by metyrapone (a corticosterone synthesis inhibitor) or increased by acute stress (predator exposure), forming an overall U-shaped relationship between corticosterone levels and memory. We then addressed whether there was a causal relationship between elevated corticosterone levels and impaired memory. If elevated corticosterone levels were a sufficient condition to impair memory, then exogenously administered corticosterone, alone, should have impaired performance. However, we found that spatial memory was not impaired in corticosterone-injected rats that were not exposed to the cat. This work demonstrates that an intermediate level of corticosterone correlated with optimal memory, and either a decrease or an increase in corticosterone levels, in conjunction with strong emotionality, impaired spatial memory. These findings indicate that fear-provoking conditions, which are known to engage the amygdala, interact with stress levels of corticosterone to influence hippocampal functioning.
Further identities for the Wishart distribution with applications in regression
Authors: Haff L. R.
Published: June 2006

Matrix analogues are given for a known scalar identity which relates certain expectations with respect to the Wishart distribution. (The scalar identity was independently derived by C. Stein and L. Haff.) The matrix analogues are more aptly called “matrix extensions.” They can be derived by using the scalar identity; nevertheless, they are seen (in quite elementary terms) to be more general than the latter. A method of doing multivariate calculations is developed from the identities, and several examples are worked in detail. We compute the first two moments of the regression coefficients and another matrix arising in regression analysis. Also, we give a new result for the matrix analogue of squared multiple correlation: the bias correction of Ezekiel (1930), a result often used in model building, is extended to the case of two or more dependent variables.
A measure of aliasing and applications to two‐level fractional factorials
Authors: Monette Georges
Published: June 2006

This paper examines some properties of a measure of aliasing proposed by Hedayat, Raktoe, and Federer (1974). It is shown that in the case of balanced orthogonal designs with no repeated treatments, minimizing the alias measure is equivalent to minimizing tr Yar(ψ). Lower bounds are found for fixed eigenvalues of the design matrix. These results are applied to two‐level fractional factorials to show that in certain cases classical fractional‐factorial designs yield minimal solutions for the alias measure.
Some limit theorems for uniform and exponential spacings
Authors: Aly Emad‐Eldin A.A.
Published: June 2006

The asymptotic distributions of spacing statistics based on exponential and uniform spacings are studied, and the corresponding rates of convergence are also given.
Estimation of the mean of an exponential distribution in the presence of an outlier
Authors: Chikkagoudar M. S. , Kunchur S. H.
Published: June 2006

Kale and Sinha (1971) have found an estimator of the mean of an exponential distribution in the présence of an outlying observation with higher expected value. Here an alternative estimator of the mean is proposed and it is compared with the estimator of Kale and Sinha (1971) and the maximum likelihood estimator given by Kale (1975). The proposed estimator is found to be more efficient than the latter two estimators in some cases.
Rules for multiplication of any polykay by polykay products of weight 5
Authors: Nagambal P.N. , Tracy Derrick S.
Published: June 2006

Nagambal and Tracy [1] provided rules for multiplication of any polykay by another of weight 5. In [2], they proposed similar rules for multiplying a polykay by polykay products of weight 5. Here all such rules are présentés explicitly.
Spectral properties of the concurrent and forecasting seasonal linear filters of the X‐11‐ARIMA method
Authors: Dagum Estela Bee
Published: June 2006

This study analyzes the properties of the linear filters of the X‐11‐ARIMA seasonal adjustment method applied for current seasonal adjustment. It provides the general formula for the combined weights that result from the ARIMA model extrapolation filters with the X‐11 seasonal‐adjustment filters. The three cases studied correspond to the three ARIMA models automatically tested by the X‐11‐ARIMA program, namely, (0, 1, 1)(0, 1, 1), (0, 2, 2)(0, 1, 1), and (2, 1. 2)(0, 1,1). The parameter values chosen reflect different degrees of flexibility of the trend‐cycle and seasonal components. It is shown that the X‐11‐ARIMA linear filters for current seasonal adjustment are very flexible; they change with both the ARIMA extrapolation model and its parameter values, contrary to those of the X‐11 program, which are fixed for a given set of options.
Asymptotic distributions of quadratic forms occurring in changepoint problems
Authors: Erasmus C. M. , Lombard F.
Published: June 2006

A stochastic‐process approach is used to derive the asymptotic distributions of quadratic forms occurring in the analysis of changepoint data.
Two‐moment approximations to some null distributions in order‐restricted inference: Unequal sample sizes
Authors: Singh Bahadur , Wright F. T.
Published: June 2006

Bartholomew's statistics for testing homogeneity of normal means with ordered alternatives have null distributions which are mixtures of chi‐squared or beta distributions according as the variances are known or not. If the sample sizes are not equal, the mixing coefficients can be difficult to compute. For a simple order and a simple tree ordering, approximations to the significance levels of these tests have been developed which are based on patterns in the weight sets. However, for a moderate or large number of means, these approximations can be tedious to implement. Employing the same approach that was used in the development of these approximations, two‐moment chisquared and beta approximations are derived for these significance levels. Approximations are also developed for the testing situation in which the order restriction is the null hypothesis. Numerical studies show that in each of the cases the two‐moment approximation is quite satisfactory for most practical purposes.
Least‐squares estimation of transition probabilities from aggregate data
Authors: Kalbfleisch J. D. , Lawless J. F.
Published: June 2006

Consider a population of n individuals that move independently among a finite set {1, 2,……, k} of states in a sequence of trials. t = 0. 1, 2,…, m. each according to a Markov chain with transition probability matrix P. This paper deals with the problem of estimating P on the basis of aggregate data which record only the numbers of individuals that occupy each of the k states at times t = 0. 1,2,……,m. Estimation is accomplished using conditional least squares, and asymptotic results are verified for the case n → ∞. A weighted least‐squares estimator is introduced and compared with previous estimators. Some comments are made on estimability questions that arise when only aggregate data are available.
First passage game
Authors: Nair K. P. K. , Laughland A. R. , Srinivasan S.
Published: June 2006

Appealing to the theory of stochastic games, a two‐person, zero‐sum first passage game, which may be viewed as a generalization of the first passage decision problem, is developed. In the first passage game, the players have stationary optional strategies and the values are unique and these can be computed using an algorithm for terminating stochastic games. It is also shown that the solution of a recurrence game is closely related to that of the first passage game. Finally, it is shown that a finite step stochastic game with nonstationary transition probabilities and payoffs can be converted to a first passage game whose solution yields a solution of the original finite step game. The first passage game so obtained has stationary transition probabilities and payoffs. Because of its special structure, the solution method reduces to a dynamic programming recursion in the context of games.
A probabilistic model for table tennis
Authors: Schulman R. S. , Hamdan M. A.
Published: June 2006

A probabilistic model for table tennis is derived and probabilities of winning and expected durations are presented for a game and for a match. A simpler model, ignoring the effects of service, is compared with the complete model.
Moment inequalities for truncated multivariate distributions
Authors: Gupta A. K. , Tracy D. S.
Published: June 2006

In this note some properties of the absolute moments of a doubly truncated arbitrary multivariate distribution are studied and several moment inequalities are derived.
Convergence faible sur des espaces topologiques uniformes et suites aléatoires d'éléments aléatoires
Authors: Kohler Boris
Published: June 2006

Après quelques résultats de convergence faible, nous donnons des théorèmes de selection pour des éléments aléatoires sur des espaces uniformes. Nous rattachons un théorème de Fernandez (1971, p. 1740) á ces résultats.
Comparison of two measures of association in two‐way contingency tables
Authors: Hamdan M. A.
Published: June 2006

Stuart's (1953) measure of association in contingency tables, tC, based on Kendall's (1962) t, is compared with Goodman and Kruskal's (1954, 1959, 1963, 1972) measure G. First, it is proved that |G| ≥ |tC|; and then it is shown that the upper bound for the asymptotic variance of G is not necessarily always smaller than the upper bound for the asymptotic variance of tC. It is proved, however, that the upper bound for the coefficient of variation of G cannot be larger in absolute value than the upper bound for the coefficient of variation of tC. The asymptotic variance of tC is also derived and hence we obtain an upper bound for this asymptotic variance which is sharper than Stuart's (1953) upper bound.
Sampling a finite population in the presence of trend and correlation: Estimation of total 305‐day lactation production in cattle
Authors: Bartlett Roy F.
Published: June 2006

This paper studies the estimation of a finite population total in the presence of trend. A practical problem of dairy science is to estimate a cow's total 305‐day milk production given a number of test‐day records. We analyze this problem as one of estimating the total of a discrete population when the population values are correlated and exhibit a trend over time. Linear prediction estimators that are BLUE for known covariance and trend function linear in unknown parameters were applied to the estimation of the milk yield total. An empirical study compares BLUE with the expansion estimator and the procedure currently used by the Canadian Record of Performance for Dairy Cattle.
The distribution of random determinants
Authors: Alagar V. S.
Published: June 2006

The exact distribution of |Δn| where Δn is a random determinant with independent and identically distributed exponential elements is given for the cases n = 2 and 3. From the investigation of the behaviour of the density functions for these cases it is conjectured that for any fixed n, the probability density of |Δn| for large values of the argument is the same as the density of (Y/n)n, where Y is a gamma random variable.
An infinite class of PBIB designs
Authors: Saha G. M. , Das A. D.
Published: June 2006

In this paper, an infinite class of partially balanced incomplete block (PBIB) designs of m+1 associate classes is constructed through the use of a series of row‐orthogonal matrices known as partially balanced orthogonal designs (PBOD) of m‐associate classes. For the purpose, a series of PBOD is obtained through a method described herein. An infinite class of regular GD designs is also reported.
Young chains and rank orders
Authors: Narayana T. V. , Savage I. Richard , Saxena K. M. Lal
Published: June 2006

Savage (1956) obtained an easily applied necessary condition for the admissibility of two‐sample rank tests under alternatives having a monotone likelihood ratio. This condition is: rank order Z is more likely than rank order Z' if the Z‐path is above the Z'‐path in Young's lattice. This condition is easily applied and allows not only the proof of the inadmissibility of the Wilcoxon test under Lehmann alternatives but it can also be used to construct explicitly uniformly better tests. For Lehmann alternatives, we obtain another necessary criterion on rank orders which makes use of dominance.