bluuebunny/crossref_metadata_2025_split huggingface dataset:
Random MAX SAT, random MAX CUT, and their phase transitions
Authors: Coppersmith Don , Gamarnik David , Hajiaghayi MohammadTaghi , Sorkin Gregory B. 
Published: May 2004

AbstractWith random inputs, certain decision problems undergo a “phase transition.” We prove similar behavior in an optimization context. Given a conjunctive normal form (CNF) formulaFonnvariables and withm k‐variable clauses, denote by maxFthe maximum number of clauses satisfiable by a single assignment of the variables. (Thus the decision problemk‐SATis to determine if maxFis equal tom.) With the formulaFchosen at random, the expectation of maxFis trivially bounded by (3/4)m⩽ 𝔼 maxF⩽m. We prove that for random formulas withm= ⌊cn⌋ clauses: for constantsc< 1, 𝔼 maxFis ⌊cn⌋ − Θ(1/n); for largec, it approaches and in the “window”c= 1 + Θ(n−1/3), it iscn− Θ(1). Our full results are more detailed, but this already shows that the optimization problemMAX2‐SATundergoes a phase transition just as the 2‐SATdecision problem does, and at the same critical valuec= 1. Most of our results are established without reference to the analogous propositions for decision 2‐SAT, and can be used to reproduce them. We consider “online” versions ofMAX2‐SAT, and show that for one version the obvious greedy algorithm is optimal; all other natural questions remain open. We can extend only our simplestMAX2‐SATresults toMAXk‐SAT, but we conjecture a “MAXk‐SATlimiting function conjecture” analogous to the folklore “satisfiability threshold conjecture,” but open even fork= 2. Neither conjecture immediately implies the other, but it is natural to further conjecture a connection between them. We also prove analogous results for randomMAX CUT. © 2004 Wiley Periodicals, Inc. Random Struct. Alg., 2004
Prediction of preterm delivery in twin pregnancy: a prospective, observational study of cervical length and fetal fibronectin testing
Authors: Gibson J. L. , Macara L. M. , Owen P. , Young D. , Macauley J. , Mackenzie F. 
Published: May 2004

AbstractObjectiveTo evaluate prospectively cervical length measurements and fetal fibronectin detection as predictors of spontaneous preterm delivery in an unselected population of twin pregnancies.MethodsTransvaginal ultrasound assessments of cervical length were performed serially at 18, 24, 28 and 32 weeks' gestation. Receiver–operating characteristic curves were generated at each time point to determine the optimal cut‐off for cervical length and rate of change in cervical length in the prediction of preterm delivery (< 35 weeks). A bedside assay for the detection of fetal fibronectin in the maternal vaginal secretions was performed prior to cervical length measurements from 24 weeks. Likelihood ratios (LRs) were used to assess the performance of each test.ResultsThe spontaneous preterm delivery rate was 16.5% in 91 studied twin pregnancies. A cervical length ≤ 25 mm at 18 weeks (LR+ 9.7, sensitivity 14.3%) and ≤ 22 mm at 24 weeks (LR+ 9.6, sensitivity 28.6%) were the best predictors of preterm delivery. A shortening of cervical length ≥ 2.5 mm per week between 18 and 28 weeks' gestation also predicted preterm delivery (LR+ 10.8, sensitivity 16.7%). There was no relationship between the detection of fetal fibronectin and preterm delivery.ConclusionsThis study confirms the value of transvaginal ultrasound assessment of cervical length as a predictor of preterm delivery in twin pregnancies. However, the poor sensitivity of this test makes it unsuitable as a single predictor of preterm delivery. Fetal fibronectin testing does not identify twin pregnancies destined to deliver prematurely. Copyright © 2004 ISUOG. Published by John Wiley & Sons, Ltd.
Three‐dimensional (3D) and 4D color Doppler fetal echocardiography using spatio‐temporal image correlation (STIC)
Authors: Chaoui R. , Hoffmann J. , Heling K. S. 
Published: May 2004

AbstractObjectiveColor Doppler echocardiography is used to visualize three transverse planes: the four‐chamber, five‐chamber, and three vessels and trachea views. Color Doppler spatio‐temporal image correlation (STIC) is a new three‐dimensional (3D) technique allowing the acquisition of a volume of data from the fetal heart that is displayed as a cineloop of a single cardiac cycle. The aim of the study was to examine the potential of color Doppler STIC to evaluate normal and abnormal fetal hearts.MethodsThis prospective study included 35 normal fetuses and 27 fetuses with congenital heart defects (CHD) examined between 18 and 35 weeks of gestation. Volume acquisition was achieved by initiating the image capture sequence from the transverse four‐chamber view. Volumes were stored for later offline evaluation using a personal computer‐based workstation in a multiplanar mode and as spatial volume rendering.ResultsSuccessful acquisition was possible in all 62 cases. The three planes could be demonstrated in 31/35 healthy fetuses and in 24/27 fetuses with CHD. Spatial volume rendering was attempted in 18 fetuses with CHD. In the four normal fetuses with inadequate visualization using color Doppler STIC, the region of interest was perpendicular to the ultrasound beam. In two fetuses with CHD inadequate visualization was related to an enlarged heart in late gestation, in which the entire cardiac volume could not be acquired. The third case was an 18‐week fetus with complex CHD and transposed great vessels in which artifacts were related to confluent color signals as a result of low resolution in the reconstructed plane.ConclusionsSTIC in combination with color Doppler ultrasound is a promising new tool for multiplanar and 3D/4D rendering of the fetal heart. Limitations may be found later in gestation in fetuses with large hearts and early in gestation as a result of low discrimination of signals. In addition, insonation perpendicular to the structure of interest does not image color Doppler signals and should be avoided during acquisition. Copyright © 2004 ISUOG. Published by John Wiley & Sons, Ltd.
What causes the vulnerability of endemic animals? A case study from Sri Lanka
Authors: Wijesinghe Mayuri R. , Brooke M. de L. 
Published: May 2004

AbstractAround the world, endemic species with restricted ranges seem to be at particular risk of extinction. When range size is controlled, lowland continental species may be especially at risk, more so than island or montane species. Our study aimed to investigate reasons behind the high vulnerability of endemic species. In Sri Lanka, large‐scale national surveys and intensive localized fieldwork established that endemic plant and animal species are mostly associated with undisturbed rainforest habitats. On the other hand, non‐endemic species used both forest and non‐forest habitats almost equally, suggesting they are less likely to suffer from deleterious edge effects. To understand the different distribution of endemic and non‐endemic species, our study focused on rats. Compared to the widespread species, the endemic rat species had a larger home range and fed on fewer species of forest fruit, possibly indicating greater specialization. The abundance of the endemic species was also negatively correlated with the abundance of the non‐endemic species, to which it was behaviourally subordinate. Greater specialization and competitive inferiority could both contribute to the vulnerability of endemic species.
Long‐distance movements of the grey‐headed flying fox (Pteropus poliocephalus)
Authors: Tidemann Christopher R. , Nelson John E. 
Published: May 2004

AbstractThe grey‐headed flying fox Pteropus poliocephalus, a nationally vulnerable species, is endemic to coastal eastern Australia, from Maryborough, Queensland, through New South Wales to Melbourne, Victoria. Pteropus poliocephalus forages at night, primarily on eucalypt blossom within 50 km of traditional camps (day roosts), usually in dense, riparian vegetation. Several attempts have been made to track long‐distance movements of P. poliocephalus across its extensive and climatically highly variable range, but the technology has been inadequate for tracking at the required speed and scale. Satellite tracking was used to monitor movements of a 2‐year‐old male P. poliocephalus, trapped at the Currie Park camp in the north of the species' range (28°48′S) from January 2000, and another from its most southerly camp, Melbourne (37°50′S), from April 2000. The first flying fox moved camp 50 km noth‐east to Dallas Park, where it stayed until March, then transited at least 15 other camps between 28°12′–32°44′S, before returning to Dallas Park in September. The second flying fox remained in Melbourne until July, then transited at least six other camps to 33°44′S, before returning to Melbourne in January 2001. Both animals made round trips of at least 2000 km, traversing >4° latitude, before returning to their camps of origin, while other animals remained. The study suggests that P. poliocephalus is a partial migrant that uses winds to facilitate long‐distance movements, and underlines the importance of management at a national scale.
Phylogenetic relationships within the family Talpidae (Mammalia: Insectivora)
Authors: Motokawa Masaharu 
Published: May 2004

AbstractThe phylogenetic relationships within the family Talpidae (Mammalia, Insectivora) were inferred from parsimonious analysis of 55 morphological characters, which were collected from 43 skulls of 22 species, and which included all of the extant genera in the current taxonomy of the Talpidae. Two equally parsimonious cladograms were obtained. The Uropsilinae, Desmaninae and Talpinae subfamilies formed monophyletic clades, and the Desmaninae and Talpinae subfamilies were sister clades. The Talpinae subfamily was subdivided into the following clades: Urotrichus, Dymecodon, Scalopus–Scapanus, Parascalops–Scapanulus, Condylura, Neurotrichus, Scaptonyx and Talpini (Talpa, Euroscaptor, Scaptochirus, Parascaptor and Mogera). The Urotrichini (Urotrichus, Dymecodon and Neurotrichus) and Scalopini (Scalopus, Scapanus, Parascalops and Scapanulus) were considered to be paraphyletic, and were defined primarily by their ancestral characteristics. Since the genus Dymecodon was not clustered with Urotrichus, it was considered to be a valid genus, and not just a junior synonym of the latter. The Asian genus Euroscaptor was found to be a paraphyletic group, and deserves further systematic revision. The evolution from semi‐fossorial habit to fully fossorial habit seems to have occurred three times in the Scalopus–Scapanus, Parascalops–Scapanulus and Talpini clades. The migration of the Talpinae to North America from Eurasia probably occurred on four separate occasions in the Scalopus–Scapanus, Parascalops, Condylura and Neurotrichus lineages.
Adult female survival, population trend, and the implications of early primiparity in a capital breeder, the southern elephant seal (Mirounga leonina)
Authors: Pistorius P. A. , Bester M. N. , Lewis M. N. , Taylor F. E. , Campagna C. , Kirkman S. P. 
Published: May 2004

AbstractAdult female survival as a potential proximate factor responsible for observed changes in southern elephant seal Mirounga leonina populations was investigated. We compared the survival rate estimates from mark–recapture data for female elephant seals from the Marion Island population (using program MARK) for two periods (pre‐ and post‐decline) during the past 15 years and with estimates from another population in southern Argentina, which had increased steadily during the same period. Survival of prime‐age adult females increased significantly by 6.2% during the latter part of the decline at Marion Island, and the survival of adult females at the colony in southern Argentina was 3.2% greater than at Marion Island after the stabilization. We thereby demonstrated the importance of adult female survival in population regulation and emphasized the importance of monitoring adult females in order to understand population changes in southern elephant seals. In addition, we investigated whether reproductive expenditure early on in life reduces future reproductive potential in the population at Marion Island. We did this by estimating and comparing future survival and breeding probabilities of females primiparous at different ages. The future annual survival and breeding probabilities of females breeding at a young age, was similar to those from females primiparous at an older age. There was also no reduced survival in the year following first breeding in young or older first time breeders. Reproductive expenditure in young primiparous females therefore did not entail future fitness costs relative to older primiparous females, and we found no evidence supporting the existence of various life‐history strategies in terms of age of primiparity within a population of southern elephant seals.
Masticatory morphological diversity and chewing modes in South American caviomorph rodents (family Octodontidae)
Authors: Olivares A. Itatí , Verzi Diego H. , Vassallo Aldo I. 
Published: May 2004

AbstractThe relationship between masticatory morphology and chewing modes in all living genera of South American rodents in the family Octodontidae was analysed. Chewing directions and the patterns of molar occlusion were assessed. Factor and regression analyses of skull and jaw characters, and attributes of the adductor musculature, especially the line of action of masseters and pterygoids, were performed to check their relations with the chewing modes. Two basic chewing strategies are present in octodontids: oblique unilateral (associated with anterolingual jaw displacement, and alternate occlusion of left and right molar series), and propalinal bilateral (associated with mostly posteroanterior jaw displacement, and simultaneous occlusion). The skull and jaw characters examined are related only partly to these chewing strategies. The temporal pattern of muscle contraction provides a possible explanation for such a functional versatility. Propalinal grinding in octodontids could be achieved through simultaneous muscle contraction, with limited reliance on the lines of action of the involved muscles. Therefore, simultaneous contraction explains a similar propalinal masticatory mode in morphologically disparate genera. In accordance with phylogenetic information, oblique unilateral chewing is primitive in octodontids, and the derived propalinal mode has been developed independently at least twice in the evolution of the family.
Temporal dynamics in spatial organization of a rodent community in the Negev Highlands (Israel)
Authors: Shenbrot Georgy , Krasnov Boris 
Published: May 2004

AbstractDynamics of a rodent community were studied in the Negev Desert Highlands (Israel) during 8 years on 24 permanent 1‐ha plots representing six main habitat types. Based on theoretical models of habitat selection, we hypothesized that niche overlap between species of the same spatial guild should increase with density faster than that between species of different guilds. Data were analysed using multivariate (principal component and discriminant) analyses to test the hypothesis. Density changes in most rodent species followed fluctuations in the amount of rainfall. Habitat niche breadth was density‐dependent in six species and density‐independent in four species. Significant habitat shifts and switches of spatial guild membership were found in three of 10 species. Pairwise values of habitat overlap were significantly and positively correlated with density only in species pairs where both species demonstrated density‐dependent variation of habitat breadth. In most other pairs of species, overlap values were density‐independent. Comparison of changes in average within‐season values of habitat overlap with density within and among spatial guilds directly supported our hypothesis demonstrating faster increase of niche overlap with density between species of the same spatial guild than between species of different guilds.
Suppression of insulin signalling by a synthetic peptide KIFMK suggests the cytoplasmic linker between DIII‐S6 and DIV‐S1 as a local anaesthetic binding site on the sodium channel
Authors: Hirose Munetaka , Kuroda Yoshihiro , Sawa Shinichi , Nakagawa Terumichi , Hirata Masashi , Sakaguchi Masahiro , Tanaka Yoshifumi 
Published: May 2004

Acetyl‐KIFMK‐amide (KIFMK) restores fast inactivation to mutant sodium channels having a defective inactivation gate. Its binding site with sodium channels could be considered to be the cytoplasmic linker (III–IV linker) connecting domains III and IV of the sodium channel α subunit. There is a close resemblance of the amino‐acid sequences between the III–IV linker and the activation loop of the insulin receptor (IR). This resemblance of the amino‐acid sequences suggests that KIFMK may also modulate insulin signalling. In order to test this assumption, we studied the effects of KIFMK and its related (KIYEK, KIQMK, and DIYET) and unrelated (LPFFD) peptides on tyrosine phosphorylation or dephosphorylation of IR in vitro.
Purified IR was phosphorylated in vitro with insulin in the presence of various synthetic peptides and lignocaine. The phosphorylation level of IR was then evaluated after SDS–PAGE separation, followed by Western blot analysis with antiphosphotyrosine antibody.
KIFMK and KIYEK inhibited insulin‐stimulated autophosphorylation of IR. Lignocaine showed similar effects, but at a higher order of concentration. KIYEK and DIYET, but not KIFMK, dephosphorylated the phosphorylated tyrosine residues. The structurally unrelated peptide LPFFD had no effect either on phosphorylation or dephosphorylation of IR.
These results indicate that KIFMK, KIYEK, and lignocaine bind with the autophosphorylation sites of IR.
The present findings also suggest that KIFMK and lignocaine bind with the III–IV linker of sodium channel α subunit.

British Journal of Pharmacology (2004) 142, 222–228. doi:10.1038/sj.bjp.0705575
Functional evidence of a role for two‐pore domain potassium channels in rat mesenteric and pulmonary arteries
Authors: Gardener M J , Johnson I T , Burnham M P , Edwards G , Heagerty A M , Weston A H 
Published: May 2004

Experiments were performed to elucidate the mechanism by which alterations of extracellular pH (pHo) change membrane potential (EM) in rat mesenteric and pulmonary arteries.
Changing pHo from 7.4 to 6.4 or 8.4 produced a depolarisation or hyperpolarisation, respectively, in mesenteric and pulmonary arteries. Anandamide (10 μM) or bupivacaine (100 μM) reversed the hyperpolarisation associated with alkaline pHo, shifting the EM of both vessels to levels comparable to that at pH 6.4. In pulmonary arteries, clofilium (100 μM) caused a significant reversal of hyperpolarisation seen at pH 8.4 but was without effect at pH 7.4.
K+ channel blockade by 4‐aminopyridine (4‐AP) (5 mM), tetraethylammonium (TEA) (10 mM), Ba2+ (30 μM) and glibenclamide (10 μM) depolarised the pulmonary artery. However, shifts in EM with changes in pHo remained and were sensitive to anandamide (10 μM), bupivacaine (100 μM) or Zn2+ (200 μM).
Anandamide (0.3–60 μM) or bupivacaine (0.3–300 μM) caused a concentration‐dependent increase in basal tone in pulmonary arteries.
RT–PCR demonstrated the expression of TASK‐1, TASK‐2, THIK‐1, TRAAK, TREK‐1, TWIK‐1 and TWIK‐2 in mesenteric arteries and TASK‐1, TASK‐2, THIK‐1, TREK‐2 and TWIK‐2 in pulmonary arteries. TASK‐1, TASK‐2, TREK‐1 and TWIK‐2 protein was demonstrated in both arteries by immunostaining.
These experiments provide evidence for the presence of two‐pore domain K+ channels in rat mesenteric and pulmonary arteries. Collectively, they strongly suggest that modulation of TASK‐1 channels is most likely to have mediated the pH‐induced changes in membrane potential observed in these vessels, and that blockade of these channels by anandamide or bupivacaine generates a small increase in pulmonary artery tone.

British Journal of Pharmacology (2004) 142, 192–202. doi:10.1038/sj.bjp.0705691
If channel inhibitor ivabradine lowers heart rate in mice with enhanced sympathoadrenergic activities
Authors: Du Xiao‐Jun , Feng Xinheng , Gao Xiao‐Ming , Tan Tze Ping , Kiriazis Helen , Dart Anthony M 
Published: May 2004

Ivabradine selectively reduces heart rate (HR) by inhibiting the cardiac pacemaker If current, thus prolonging the duration of spontaneous depolarization in the sinus node. The activity of ivabradine under conditions of enhanced sympathoadrenergic activity has been addressed by investigating the effects of repeated oral administration in mice with sympathoadrenergic activation due to either stress, cardiac‐restricted overexpression of β2‐adrenergic receptors (β2AR), or β‐agonist administration. HR and left ventricular fractional shortening (FS) were determined by echocardiography.
Initial experiments showed that the conscious restrained state was associated with stress‐mediated sympathetic activation, while sympathetic withdrawal occurred under anaesthetized conditions. In wild‐type mice, ivabradine reduced HR under both conscious and anaesthetized states, with a similar degree in absolute reduction under both states. FS was unchanged by the treatment.
Ivabradine was similarly effective in reducing HR in the β2AR transgenic mice. Further, ivabradine at 10 mg kg−1 day−1 reduced the maximal HR increase in response to the β‐agonist isoproterenol, without modifying the response of contractile parameters.
These data indicate that oral administration of ivabradine in mice reduces HR while ventricular performance is maintained. This specific HR‐reducing action of ivabradine is well preserved under conditions that are associated with significant activation of the sympathoadrenergic system.

British Journal of Pharmacology (2004) 142, 107–112. doi:10.1038/sj.bjp.0705696
Endocannabinoid‐mediated short‐term synaptic plasticity: depolarization‐induced suppression of inhibition (DSI) and depolarization‐induced suppression of excitation (DSE)
Authors: Diana Marco A , Marty Alain 
Published: May 2004

Depolarization‐induced suppression of inhibition (DSI) and depolarization‐induced suppression of excitation (DSE) are two related forms of short‐term synaptic plasticity of GABAergic and glutamatergic transmission, respectively. They are induced by calcium concentration increases in postsynaptic cells and are mediated by the release of a retrograde messenger, which reversibly inhibits afferent synapses via presynaptic mechanisms.We review here:

The evidence accumulated during the 1990s that has led to the conclusion that DSI/DSE rely on retrograde signaling.
The more recent research that has led to the identification of endocannabinoids as the retrograde messengers responsible for DSI/DSE.
The possible mechanisms by which presynaptic type 1 cannabinoid receptors reduce synaptic efficacy during DSI/DSE.
The possible modes of induction of DSI/DSE by physiological activity patterns, and the partially conflicting evaluations of the calcium concentration increases required for cannabinoid synthesis.
Finally, the relation between DSI/DSE and other forms of long‐ and short‐term synaptic inhibition, which were more recently associated with the production of endocannabinoids by postsynaptic cells.

British Journal of Pharmacology (2004) 142, 9–19. doi:10.1038/sj.bjp.0705726