bluuebunny/crossref_metadata_2025 huggingface dataset:
The relationship between osteonecrosis of the proximal femur identified by MRI and lesions proven by histological examination
Authors: Calder J. D. , Hine A. L. , Pearse M. F. , Revell P. A.
Published: February 2008

Total hip replacement in patients with advanced osteonecrosis of the femoral head is often complicated by early loosening of the femoral component. Recent evidence has suggested that abnormal bone extending into the proximal femur may be responsible for the early failure of the femoral component. We aimed to identify which patients were at high risk of early failure by evaluating gadolinium-enhanced MR images of histologically-confirmed osteonecrotic lesions beyond the femoral head.

Although the MR signal intensity has been shown to correlate well with osteonecrosis in the femoral head, it was found to be relatively insensitive at identifying lesions below the head, with a sensitivity of only 51% and a predictive value of a negative result of only 48%. However, the specificity was 90%, with the predictive value of a positive MRI finding being 86%. Only those patients with osteonecrosis of the femoral head secondary to sickle-cell disease, who are known to be at high risk of early loosening, had changes in the MR signal in the greater trochanter and the femoral shaft. This observation suggests that changes in the MR signal beyond the femoral head may represent osteonecrotic lesions in areas essential for the fixation of the femoral component. Pre-operative identification of such lesions in the neck of the femur may be important when considering hip resurfacing for osteonecrosis of the femoral head, following which early loosening of the femoral component and fracture of the neck are possible complications.
Normal compartment pressures of the lower leg in children
Authors: Staudt J. M. , Smeulders M. J. C. , van der Horst C. M. A. M.
Published: February 2008

Compartment pressures have not previously been studied in healthy children. We compared the pressures in the four lower leg compartments of healthy children with those of healthy adults.

We included patients aged between two months and six years, and measured the pressures in 80 compartments of 20 healthy children using simple needle manometry. Measurements were repeated in a control group of 20 healthy adults.

The mean compartment pressure in the lower leg in children was significantly higher than in adults (p < 0.001). On average, pressures in the four compartments varied between 13.3 mmHg and 16.6 mmHg in the children and between 5.2 mmHg and 9.7 mmHg in the adults. The latter is in accordance with those recorded in the literature. The mean arterial pressure did not relate to age or to pressure in the compartment.

The findings of this study that the normal compartment pressure of the lower leg in healthy children is significantly higher than that in adults may be of considerable significance in clinical decision-making in children of this age.
Stimulation of salmon calcitonin on secretion of 17β-estradiol by the ovarian follicles of common carp, Cyprinus carpio
Authors: Paul Sudipta , Mukherjee Dola , Pramanick Kousik , Kundu Sourav , Bhattacharyya S P , De Priyanka , Mukherjee Dilip
Published: February 2008

The effects of salmon calcitonin (sCT) on the secretion of 17β-estradiol (E2) were examined in female common carp, Cyprinus carpio. Vitellogenic stage fish adapted to high-Ca water were i.p. injected with vehicle, sCT, human chorionic gonadotropin (hCG), or hCG plus sCT. To determine whether ovarian follicles are equipped with CT receptors, a CT binding assay was conducted. In the in vitro experiments, vitellogenic follicles were incubated with stimulators and inhibitors. Administration of sCT increased the basal and hCG-stimulated E2 release in vivo and in vitro. Binding characteristics of [125I]sCT to plasma membrane preparation of carp ovarian follicles showed saturability with high-affinity (Kd=48.48 pmol/l and Bmax=1.2 pmol/mg protein). To clarify the mechanism of E2 production by sCT, in vitro effect of sCT and hCG on aromatase activity (conversion of testosterone to E2) and cytochrome P450 aromatase (P450arom) gene expression in carp ovarian follicles were investigated. Salmon CT-stimulated both aromatase activity and P450arom gene expression in ovarian follicles of carp. sCT-stimulated E2 release by the ovarian follicles in vitro was augmented in the presence of dibutyryl cAMP. Inhibitor of protein kinase A (PKA), SQ 22536 inhibited sCT-stimulated steroid production in a dose-dependent manner. Specific inhibitor of protein kinase C (PKC), NPC-15437 dihydrochloride had no inhibitory effects on sCT-induced E2 release. The present study indicates that sCT binds specifically to carp ovary and stimulates E2 production by increasing the activity of cytochrome P450 aromatase and P450arom gene expression. The results further suggest that stimulatory action of sCT on E2 production is mediated through cAMP pathway.
Kisspeptin-13 inhibits insulin secretion without affecting glucagon or somatostatin release: study in the perfused rat pancreas
Authors: Silvestre R A , Egido E M , Hernández R , Marco J
Published: February 2008

Kisspeptins are a family of peptides encoded by the KISS1 gene, which binds to G-protein-coupled receptor (GPR54), an orphan GPR54 related to galanin receptors. Endogenous forms composed of 54, 14, and 13 amino acids have been identified. Kisspeptin and GPR54 mRNAs have been detected in pancreatic B and A cells. Furthermore, kisspeptin-54 has been shown to slightly stimulate the last phase of glucose-induced insulin secretion in mouse and human islets and to inhibit insulin release in MIN6 cells. We have investigated the effect of kisspeptin-13 on insulin, glucagon, and somatostatin secretion. The study was performed in the perfused rat pancreas. Glucose, arginine, carbachol, and exendin-4 were used as secretagogues. Hormones were measured by RIA. Kisspeptin-13 reduced glucose-induced insulin secretion in a dose-dependent manner (IC50=1.2 nM) and inhibited the insulin responses to both carbachol and exendin-4. Kisspeptin-13 blocked arginine-induced insulin secretion without affecting the glucagon or somatostatin responses to this amino acid, thus indicating that kisspeptin-13 influences B cells directly, rather than through an A- or D-cell paracrine effect. The reduction of the insulin response to exendin-4 induced by kisspeptin-13 was also observed in pertussis toxin-treated rats, thus suggesting an inhibition independent of Gi proteins. In view of the potent insulinostatic effect of kisspeptin-13, it is tempting to speculate that kisspeptins may be implicated in the regulation of B-cell secretion.
Physiological functions of the imprinted Gnas locus and its protein variants Gαs and XLαs in human and mouse
Authors: Plagge Antonius , Kelsey Gavin , Germain-Lee Emily L
Published: February 2008

The stimulatory α-subunit of trimeric G-proteins Gαs, which upon ligand binding to seven-transmembrane receptors activates adenylyl cyclases to produce the second messenger cAMP, constitutes one of the archetypal signal transduction molecules that have been studied in much detail. Over the past few years, however, genetic as well as biochemical approaches have led to a range of novel insights into the Gαs encoding guanine nucleotide binding protein, α-stimulating (Gnas) locus, its alternative protein products and its regulation by genomic imprinting, which leads to monoallelic, parental origin-dependent expression of the various transcripts. Here, we summarise the major characteristics of this complex gene locus and describe the physiological roles of Gαs and its ‘extra large’ variant XLαs at post-natal and adult stages as defined by genetic mutations. Opposite and potentially antagonistic functions of the two proteins in the regulation of energy homeostasis and metabolism have been identified in Gnas- and Gnasxl (XLαs)-deficient mice, which are characterised by obesity and leanness respectively. A comparison of findings in mice with symptoms of the corresponding human genetic disease ‘Albright's hereditary osteodystrophy’/‘pseudohypoparathyroidism’ indicates highly conserved functions as well as unresolved phenotypic differences.
Prolactin stimulates ubiquitination, initial internalization, and degradation of its receptor via catalytic activation of Janus kinase 2
Authors: Swaminathan Gayathri , Varghese Bentley , Thangavel Chellappagounder , Carbone Christopher J , Plotnikov Alexander , Kumar K G Suresh , Jablonski Elizabeth M , Clevenger Charles V , Goffin Vincent , Deng Luqin , Frank Stuart J , Fuchs Serge Y
Published: February 2008

Prolactin (PRL) activates its receptor to initiate signal transduction pathways (including activation of Janus kinases, Jak) but also stimulates downregulation of this receptor to limit the magnitude and duration of signaling. Degradation of the long form of PRL receptor (PRLr) depends on its phosphorylation on Ser349 that is required to facilitate PRLr ubiquitination. Signaling events that mediate PRL-induced degradation of PRLr remain to be elucidated. Here, we investigated the role of Jak2 activity in ligand-triggered increase of PRLr phosphorylation on Ser349, PRLr ubiquitination, endocytosis, and degradation. Using Jak2 reconstitution in Jak2-null cells as well as pharmacologic approaches, we found that treatment with PRL (but not with PRLr antagonist) promotes phosphorylation of PRLr on Ser349 and accelerates endocytosis of PRLr. Furthermore, PRL-stimulated PRLr phosphorylation, endocytosis, and degradation in Jak2-null cells reconstituted with wild type but not with catalytically inactive Jak2. We discuss how Jak2-mediated signaling might be transduced into Ser349 phosphorylation of PRLr as well as its ubiquitination and endocytosis.
Short pulse, diode pumped, passively Q-switched Nd:YAG laser at 946 nm quadrupled for UV production
Authors: Kimmelma Ossi , Tittonen Ilkka , Buchter Scott C.
Published: February 2008

We report on a compact UV-laser with a short pulse length of 1.9 ns at 236 nm. A passively Q-switched quasi-three-level Nd:YAG laser at 946 nm acts as the pump source. UV pulses are produced by two consecutive single-pass frequency doubling events, the first one from IR to blue with a BIBO crystal and the second one from blue to deep-UV with a β-BBO crystal. Conversion efficiency from 946 nm to 473 nm is 28% and from blue to UV 7%. Average power for UV is 7.6 mW with a energy and peak power of 230 nJ, and 120 W respectively.
Biopartitioning micellar chromatography separation methods: modelling quantitative retention–activity relationships of cephalosporins
Authors: Wu Li‐ping , Ye Li‐ming , Chen Cong , Wu Jia‐qi , Chen Yu
Published: February 2008

In this article, recent applications of chromatographic systems, particularly biopartitioning micellar chromatography (BMC) systems based on amphiphilic structures, have been reported. The aim is to take a look at the capability of quantitative retention–activity relationship (QRAR) models with BMC to describe and/or estimate the bioactivity of cephalosporins. Better qualification of BMC systems was obtained according to the octanol–water partition coefficient (log P); the bioactivity parameters (Lag‐T, T1/2β, F%, T1/a, P%, AUC and Cmax) were correlated with the retention factors of cephalosporins processed by Alltech‐chromstation software, and the classical data were compared with the predictive values based on QRAR models. The results indicate that using only one descriptor (the retention factor, k) to explain the pharmacokinetic and pharmacodynamic properties of cephalosporins is adequate, and this in vitro approach is an advanced tool for pharmacodynamics research. Copyright © 2008 John Wiley & Sons, Ltd.
ChemInform Abstract: Oxidation of Alcohols with Hydrogen Peroxide Catalyzed by Molybdenum(VI)—Peroxo Complex under Solvent‐Free Conditions.
Authors: Luan Yi , Wang Ge , Luck Rudy L. , Yang Mu , Han Xiao
Published: February 2008

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: Reductive Amination of Carbonyl Compounds with NaBH4—H3PW12O40 in THF and under Solvent‐Free Conditions.
Authors: Alinezhad Heshmatollah , Ardestani Ehsan
Published: February 2008

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: A Novel and Efficient Synthesis of 2‐Aryl‐2H‐indazoles via SnCl2‐Mediated Cyclization of 2‐Nitrobenzylamines.
Authors: Shi Da‐Qing , Dou Guo‐Lan , Ni Sai‐Nan , Shi Jing‐Wen , Li Xiao‐Yue , Wang Xiang‐Shan , Wu Hui , Ji Shun‐Jun
Published: February 2008

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: An Expeditious “Green” Michael Addition of Nitro Methane to Benzimidazole Chalcones in the Presence of TBAB as Surface Catalyst.
Authors: Dubey P. K. , Reddy P. V. V. Prasada , Srinivas K.
Published: February 2008

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: A [3 + 3] Anellation Approach to (+)‐Rhopaloic Acid B.
Authors: Brioche Julien C. R. , Goodenough Katharine M. , Whatrup David J. , Harrity Joseph P. A.
Published: February 2008

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: A Novel One‐Pot Synthesis of Pyrroloquinoline and Pyrroloisoquinoline Derivatives in Ionic Liquid.
Authors: Ma Chen , Ren Yan , Zhang Qun , Ding Kai , Zhao Jun , Zhang Dongju
Published: February 2008

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
ChemInform Abstract: Nucleophilic Additions and Redox Reactions of Polyhydroxypyrroline N‐Oxides on the Way to Pyrrolidine Alkaloids: Total Synthesis of Radicamine B (I).
Authors: Merino Pedro , Delso Ignacio , Tejero Tomas , Cardona Francesca , Goti Andrea
Published: February 2008

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
Nanocrystalline hydroxyapatite coatings from ultrasonated electrolyte: Preparation, characterization, and osteoblast responses
Authors: Narayanan R. , Kim So‐Young , Kwon Tae‐Yub , Kim Kyo‐Han
Published: February 2008

An electrochemical method of producing nanograined hydroxyapatite coatings on titanium surface is reported in this article. The electrolyte contained Ca(NO3)2 and NH4H2PO4 in the molar ratio of 1.67:1. The electrolyte had physiological pH and was ultrasonically agitated throughout the time of electrolysis. Coatings were deposited for 30 minutes at 10 and 15 mA/cm2 and contained monohydroxyapatite phase whose grain sizes were 18 and 25 nm, respectively. These sizes are comparable with the grain size of bone. Small globules of hydroxyapatite covered the coating surface completely. Cell viability and total protein assay studies were carried out using SaOS‐2 human osteoblast‐like cell line. Of the two, the coating produced at 10 mA/cm2 showed higher viability and protein activity and seems to be a promising material for osseointegration. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res 2008
Patients' predilections regarding informed consent for hospital treatments
Authors: Upadhyay Shweta , Beck Andrew , Rishi Adeel , Amoateng‐Adjepong Yaw , Manthous Constantine A.
Published: February 2008

BACKGROUND

Respect for patient autonomy is a core principle of American medicine. Informed consent is required for surgical procedures and blood transfusions but not for most medical treatments of hospitalized patients.

HYPOTHESIS

If given the option, patients want to give permission for common medical therapies during hospitalization.

SUBJECTS

Participants in the study were patients admitted to the medical service of a 350‐bed community teaching hospital.

METHODS

A questionnaire comprising 4 scenarios of varying risk/benefit ratios was administered to all patients who agreed to participate.

RESULTS

A total of 634 patients were admitted to the medicine service between June and August 2006. Two hundred and ten patients (103 men, 107 women), with a mean age (± SE) of 63.3 ± 1.1 years, agreed to answer the questionnaire. Of these patients, 85% wished to participate in even trivial medical decision making (ie, potassium supplementation), 92% wished to participate in treatments with moderate risk (ie, diuretic for congestive heart failure). When a risk was initially posed as less than a 5% risk of brain hemorrhage and benefits of therapy were substantially higher (eg, thrombolysis for pulmonary embolus), 93% wanted to make the decision. If the risk of brain hemorrhage was 20% or greater, 95% wanted to make the decision. Younger patients (<65 years) were more likely to prefer requiring doctors to obtain their “permission no matter what” than were older patients (≥65 years), and older patients were more likely to waive consent across levels of risk.

CONCLUSIONS

Most acutely ill hospitalized medicine patients wished to participate in even the most mundane aspects of their medical decision making. Although it is not logistically feasible to obtain informed consent for every treatment of every hospitalized patient, clinicians should be aware of patients' predilections and might consider offering opportunities for patients to participate in clinical decision making, especially for therapies that carry substantial risk. Journal of Hospital Medicine 2008;3:6–11. © 2008 Society of Hospital Medicine.
Limb bones asymmetry and stress in medieval and recent populations of Central Europe
Authors: Kujanová M. , Bigoni L. , Velemínská J. , Velemínský P.
Published: February 2008

Monitoring the degree of asymmetry in different parts of the human body can contribute to population studies, as it may be connected indirectly with the social structure, living conditions, and also with biomechanical stress affecting the person. Analysis of asymmetry may also assess preferential use of the right or left of the body during specific activities. This study is based on the measurements of bones of the upper and lower limbs of skeletons derived from the remarkable medieval cemeteries of Mikulčice‐Kostelisko (78 male, 132 female) and Prušánky (66 male, 69 female) (9th–12th centuries AD), and a series of skeletons representing a recent population from Bohemia (143 male, 157 female). The objective was to assess directional asymmetry (DA), fluctuating asymmetry (FA) and antisymmetry (AS) of the dimensions of the evaluated bones, and to use these data to compare the characteristics of the medieval and recent populations. DA was recorded in most dimensions. In the upper limb, the humerus exhibited the greatest expression of asymmetry, and, with the exception of the clavicle, DA was always more pronounced on the right side. Conversely, DA was less prevalent in the lower limb bones. It was more pronounced on the transverse, sagittal and circumferential dimensions of the diaphyses and epiphyses than on the length, and in most cases it was on the left side. The FA values were very low, and almost negligible in relation to the size. Nevertheless, FA was markedly more frequent on the lower than on the upper limb. In contrast to the medieval population, the recent population had higher FA and DA values. Thus, we propose that people from this medieval population were subjected to lower developmental stress than the recent sample. Copyright © 2008 John Wiley & Sons, Ltd.
Non‐Gaussian conductance noise in disordered electronic systems
Authors: Orlyanchik V. , Kozub V. I. , Ovadyahu Z.
Published: February 2008

The results of conductance‐noise experiments on disordered films of crystalline indium oxide in their glassy phase are discussed. The power‐spectrum of the noise has the usual 1/f form, and when measured under small bias, the noise is Gaussian even in samples as small as 2 mm. However at larger voltages V used in the conductance measurements the noise may acquire non‐Gaussian features with a non‐trivial dependence on V. Theoretical model relating this behavior to a non‐linear effect inherent to electronic transport in a hopping system is presented. It is concluded that the non‐Gaussian features can be observed whenever the systemis glassy. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Longitudinal resistivity in the quantum Hall effect regime in a split‐gate Si MOSFET with variable electron density
Authors: Shlimak I. , Friedland K.‐J. , Kravchenko S. V. , Ginodman V. , Butenko A. , Klapwijk T. M.
Published: February 2008

Longitudinal resistivity in the quantum Hall effect regime was measured in a Si MOSFET sample in which split‐gate allows to vary the electron density and filling factor in different parts of the sample. In case of equal gate voltages on both sides of the split, the resistance, measured across the split in zero and weak magnetic fields, is larger due to electron scattering by split‐induced potential barrier. However, in strong magnetic fields, the additional resistance disappears because the current flows mostly via the edge channels along the equipotential curves. In case of different gate voltages, the longitudinal resistance is different for opposite sides of the sample because the Hall voltage difference is added only to one side of the sample depending on the sign of the gradient of gate voltages and magnetic field direction. An increase of longitudinal resistance was observed when electrons across the split occupy Landau levels with opposite spin orientation. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Kubo conductivity in the IQHE regime within Hartree‐Fock
Authors: Sohrmann Christoph , Römer Rudolf A.
Published: February 2008

We compute the Kubo conductivity for mesoscopic quantum Hall samples taking into account the Coulomb interaction at the level of a Hartree‐Fock approximation. We first explain how to compute the conductivity by rewriting the matrix elements of the position operator in terms of phase‐shifted wave functions. Next, varying both magnetic field B and charge density ne, we can show that the resulting conductivity data is very different from a non‐interacting approach. Regions around the quantum Hall plateaus at integer filling factors remain quantized and the range of these quantized regions agrees with estimates based on a breakdown of screening condition. However, in the transition regions of linear screening, we find no evidence for stripes in the conductivity, contrary to recent experiments (D. H. Cobden et al., Phys. Rev. Lett. 82, 4695 (1999), T. Machida et al., Phys. Rev. 63(4), 045318 (2001) [1, 2]). This, together with an argument given in [2], seems to suggest an effect beyond numerically tractable system sizes. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Entanglement in disordered systems at criticality
Authors: Varga Imre , Méndez‐Bermúdez José Antonio
Published: February 2008

Entanglement is a physical resource of a quantum system just like mass, charge or energy. Moreover it is an essential tool for many purposes of nowadays quantum information processing, e.g. quantum teleportation, quantum cryptography or quantum computation. In this work we investigate an extended system of N qubits. In our system a qubit is the absence or presence of an electron at a site of a tight‐binding system. Several measures of entanglement between a given qubit and the rest of the system and also the entanglement between two qubits and the rest of the system are calculated in a one‐electron picture in the presence of disorder. We invoke the power law band random matrix model which even in one dimension is able to produce multifractal states that fluctuate at all length scales. The concurrence, the tangle and the entanglement entropy all show interesting scaling properties. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Central moments in quantum chemistry
Authors: Small David W. , Head‐Gordon Martin
Published: February 2008

We define central moments of operators on finite‐dimensional vector spaces and study some of their basic aspects. Central moments may be viewed as generalizations of the dispersion of a Hermitian operator. We show how eigenvalues may be represented by central moments, and how central moments may be used to obtain Krylov subspace approximations for operators on inner product spaces. We show that central‐moments approximations are compatible with the concepts of size‐consistency in quantum chemistry, and we use this to suggest a foundation for central‐moments approximations in Coupled Cluster theory. © 2008 Wiley Periodicals, Inc. Int J Quantum Chem, 2008
L2‐absolute and input‐to‐state stabilities of equations with nonlinear causal mappings
Authors: Gil' M. I.
Published: February 2008

Nonlinear scalar equations with causal mappings are considered. These equations include differential, difference, differential‐delay, integro‐differential and other traditional equations. Estimates for the L2‐norms of solutions are established. These estimates give us explicit conditions for the absolute and input‐to‐state stabilities of the considered equations. The Aizerman‐type problem from the theory of absolute stability is also discussed.

The suggested approach enables us to consider various classes of systems from the unified point of view. Copyright © 2008 John Wiley & Sons, Ltd.
The ‘lead vessel’: a vascular ultrasound feature of metastasis in the ovaries
Authors: Testa A. C. , Mancari R. , Di Legge A. , Mascilini F. , Salutari V. , Scambia G. , Ferrandina G.
Published: February 2008

Objective

To investigate, in a series of metastatic and primary invasive ovarian lesions examined by color Doppler, the prevalence of a main peripheral vessel penetrating into the central part of the ovarian mass with a tree‐shaped morphology, defined as the ‘lead vessel’.

Methods

This was a retrospective study of 31 patients with histopathologically confirmed metastatic involvement of the ovary and 106 patients with confirmed primary invasive ovarian carcinoma, who had undergone standardized ultrasound examination, with established definitions of ultrasound characteristics. We retrieved sonographic images and videoclips, focusing on the detection of the lead vessel.

Results

The presence of the lead vessel was detected in 11/31 (35.4%) metastatic ovarian tumors, and in only two (0.01%) cases of primary ovarian carcinoma (P = 0.0001). At color Doppler analysis, metastatic ovarian lesions were characterized by significantly lower pulsatility index (P = 0.0001) and resistance index (P = 0.0001) values, and significantly higher peak systolic velocity (P = 0.0002) and time‐averaged maximum velocity (P = 0.04) values, when compared with primary ovarian carcinomas. The lead vessel was detected in 11/21 (52%) solid metastatic lesions and in no cases of multilocular or multilocular‐solid lesions (P = 0.008).

Conclusion

The lead vessel is a novel sonographic feature of vascular morphology in solid ovarian metastases. The more frequent observation of this feature in metastatic ovarian tumors compared with primary invasive ovarian carcinomas warrants further investigation in order to explore its potential role in the diagnosis of metastatic ovarian masses. Copyright © 2008 ISUOG. Published by John Wiley & Sons, Ltd.
Evolution of strength and hydraulic connectivity during dehydration: Results from a microcrack model
Authors: Simpson Guy D. H.
Published: February 2008

A two‐dimensional cellular automaton model based on the elastic mechanics of tensile (mode I) microcracks was developed to investigate the evolution of rock strength and hydraulic connectivity during progressive dehydration. Fluid produced by dehydration is assumed to be accommodated by microcracks, which propagate through a simulated rock matrix owing to elevated fluid pressures. Crack propagation affects rheology by stress relaxation and interaction, and it affects hydrology by permitting fluid flow between neighboring cracks. Numerical simulations with undrained boundary conditions show that reactions releasing small quantities of fluid (<0.25 wt %) in a rock matrix with zero initial hydraulic connectivity induce large strength reductions (approximately 80–90%). Strength reduction occurs abruptly at the onset of dehydration and continues until approximately 10% reaction, when a low‐strength plateau is reached. Subsequent reaction causes almost no further effect on rock strength until the percolation threshold is attained, at which point the strength drops to zero. Results with drained boundary conditions yield similar strength reductions before hydraulic connectivity of the crack network is achieved. Thereafter, fluid drainage allows partial strength recovery. The results indicate that the dominant rheological response induced by dehydration is caused by the generation of fluid overpressures and is unrelated to the establishment of hydraulic connectivity coinciding with the percolation threshold. Although rocks characterized by zero initial hydraulic connectivity retain additional strength relative to rocks with initial hydraulic connectivity, the magnitude of this additional strength is small (<20% original strength).
Long‐period magnetospheric‐ionospheric perturbations during northward interplanetary magnetic field
Authors: Huang Chao‐Song , Sofko G. J. , Koustov A. V. , MacDougall J. W. , Greenwald R. A. , Ruohoniemi J. M. , Villain J. P. , Lester M. , Watermann J. , Papitashvili V. O. , Hughes W. J.
Published: February 2008

In this paper we present observations of long‐period magnetospheric‐ionospheric perturbations during northward interplanetary magnetic field (IMF). On November 10–11, 1998, the IMF was northward for 29 hours. The solar wind and IMF parameters were relatively steady. After the IMF had been northward for 14 hours, strong ionospheric velocity (or electric field) perturbations were observed by the Iceland West HF radar in the postmidnight/dawn sector. The velocity perturbations showed periods in the range 50–60 min, with a mean value ∼54 min. The Super Dual Auroral Radar Network observed periodic changes of nightside ionospheric convection. For each cycle a large‐scale convection cell formed around 0200 magnetic local time (MLT) near magnetic latitude 70° and grew for ∼30 min. The convection cell then moved eastward with a mean velocity of ∼1.4 km s−1. The final position of the cell focus was around 0600 MLT near magnetic latitude 77°. Ground magnetometers recorded weak magnetic perturbations with periods 50–60 min in both the premidnight and postmidnight sectors. The GOES 8 satellite also observed magnetospheric magnetic field perturbations with similar periods at L ∼ 6 on the nightside. The satellite and the key radars which observed the convection oscillations are nearly magnetically conjugate, so the good temporal correlation between the satellite and radar data indicates that the magnetospheric and ionospheric perturbations have a common source. We propose that the magnetospheric‐ionospheric perturbations originated within the magnetosphere. The transformation of the magnetospheric tail from an extended to a more dipolar shape during northward IMF is associated with 40–60 min period global tail oscillations which ultimately result in the generation of field‐aligned currents and nightside ionospheric convection vortices near X = −10 RE. If the proposed mechanism is correct, it will be possible to infer the magnetospheric cavity shape from the measured periodicity of the tail oscillations during northward IMF.
Effects of a large mesospheric temperature enhancement on the hydroxyl rotational temperature as observed from the ground
Authors: Melo Stella M. L. , Lowe R. P. , Pendleton W. R. , Taylor M. J. , Williams B. , She C. Y.
Published: February 2008

The rotational temperature obtained from the rotational population distribution in the bands of the hydroxyl airglow has been shown to be a suitable proxy for the temperature at a height of 87 km [She and Lowe, 1998]. In this paper we examine in detail simultaneous observations on November 2–3, 1997, at Fort Collins, Colorado (41°N, 105°W), with both a sodium temperature lidar and the Coupling, Energetics, and Dynamics of Atmospheric Regions (CEDAR) OH mesospheric temperature mapper during which significant differences between the hydroxyl and lidar temperatures occur. The large differences are associated with a major temperature enhancement in the region of the peak of the hydroxyl emission. We model the effect on the shape of the emission rate profile of the hydroxyl airglow caused by the large temperature enhancement observed on this night by the lidar. As a result of the temperature sensitivity of the processes that give rise to the airglow, the profile shows major distortions from its normal shape. These distortions in turn lead to hydroxyl rotational temperatures that differ significantly from the 87‐km lidar observations. The mean rotational temperature deduced in this way agrees well with the observed values. Such deviations in the temperature are expected to be rare, occurring only when a large temperature enhancement occurs near the peak of the airglow emission profile.
Simulations of Alfvén waves in the geomagnetic tail and their auroral signatures
Authors: Wright Andrew N. , Allan W.
Published: February 2008

Observations show that Ultra‐Low Frequency (ULF) Alfvén waves in the magnetotail have distinctive properties depending upon their location. In particular, those in the plasma sheet boundary layer (PSBL) have a larger amplitude and favor earthward propagation compared to those in the tail lobe which have the polarization of standing waves. The PSBL waves are also associated with electron acceleration and optical auroral emissions that exhibit equatorward motion. In this paper we present simulations of MHD wave coupling in the magnetotail to support an explanation for how Alfvén waves with these properties may be established. The simulations also suggest the waves should have periods from 5 min to >20 min, and produce auroral emissions in the ionosphere having a latitudinal range of 40–130 km and equatorward speed of order 1 kms–1. Field aligned currents are typically a few μAm−2.
Reconnection voltage as a function of IMF clock angle
Authors: Fedder J. A. , Mobarry C. M. , Lyon J. G.
Published: February 2008

Magnetic reconnection between the interplanetary magnetic field (IMF) and the geomagnetic field is thought to play a major role in the transfer of solax wind momentum and energy to the magnetosphere. Both analytic modeling and analysis of geophysical data have shown that this coupling process should be a sensitive function of the clock angle of the IMF. In this letter we present results from a 3‐dimensional, magnetohydrodynamic (MHD), global numerical simulation code for the reconnection voltage between the closed geomagnetic field and the IMF as a function of the IMF clock angle. These results are consistent with a sin (θ/2) functional behavior.
Observations in the transverse ion energization region
Authors: Whalen B. A. , Watanabe S. , Yau A. W.
Published: February 2008

We present here the first direct observations of thermal (0 ≤ E/Q ≤ 25 Volts) and suprathermal (E/Q > 50 Volts) ion distributions from the Suprathermal Ion Mass Spectrometer (SMS) on the EXOS‐D spacecraft in and near the Transverse Ion Energization (TIE) region. It is shown that the TIE region exists on field lines closely related to the auroral zone and at altitudes which vary between 3000 to 6000 km on the day side. This process also occurs on the night side at lower altitudes, but no clear examples when the spacecraft was in the TIE region at these local times have been found to date. The altitude range over which the energization occurs is narrow, less than 100 km. In the region, all ions (major and minor species) are energized to approximately the same energy (temperature) perpendicular to the magnetic field (
) and ejected into the magnetosphere by the gradient
force. Above the region, the energized plasma expands outward along magnetic field lines forming “conic” distributions. However, distribution function observations above the TIE region indicate that significant variations from that expected from conservation of the first invariant occur when the ions have travelled only a few thousand kilometers upwards from the source.
The neutral thermosphere at Arecibo during geomagnetic storms
Authors: Burnside R. G. , Tepley C. A. , Sulzer M. P. , Fuller‐Rowell T. J. , Torr D. G. , Roble R. G.
Published: February 2008

Over the past five years, simultaneous incoherent scatter and optical observations have been obtained at Arecibo, Puerto Rico, during two major geomagnetic storms. The first storm we examine occurred during the World Day campaign of 12–16 January 1988, where on 14 January 1988, Kp values greater than 7 were recorded. An ion‐energy balance calculation shows that atomic oxygen densities at a fixed height on 14 January 1988 were about twice as large as they were on the quiet days in this period. Simultaneous radar and Fabry‐Perot interferometer observations were used to infer nighttime O densities on 14–15 January 1988 that were about twice as large as on adjacent quiet nights. On this night, unusually high westward ion velocities were observed at Arecibo. The Fabry‐Perot measurements show that the normal eastward flow of the neutral wind was reversed on this night. The second storm we examine occurred on the night of 13–14 July 1985, when Kp values reached only 4+, but the ionosphere and thermosphere responded in a similar manner as they did in January 1988. On the nights of both 13–14 July 1985 and 14–15 January 1988, the electron densities observed at Arecibo were significantly higher than they were on nearby geomagnetically quiet nights. These results indicate that major storm effects in thermospheric winds and composition propagate to low latitudes and have a pronounced effect on the ionospheric structure over Arecibo.
Poynting flux measurements on a satellite: A diagnostic tool for space research
Authors: Kelley M. C. , Knudsen D. J. , Vickrey J. F.
Published: February 2008

The first satellite observations of the total field‐aligned component of the quasi‐dc Poynting flux are presented for two passes over the polar region, one in the noon sector and one in the afternoon. The energy input due to electron precipitation is also presented. In the noon pass the downward Poynting flux in the auroral oval was comparable to the kinetic energy input rate. The peak electromagnetic energy input rate of 6 ergs/(cm² s) equaled the peak particle input while the integrated electromagnetic value along the trajectory was 60% that of the particles. In the afternoon pass the peak electromagnetic energy input was also about 6 ergs/(cm² s), but the peak particle energy was 6 times this value. The average electromagnetic input was 10% of the particle input for the pass. In this study we can measure the Poynting flux only over a limited range of scale sizes; thus the contribution to the total energy budget in the polar cap cannot be determined. Both passes show small regions characterized by upward Poynting flux suggesting a neutral wind dynamo. There is also evidence during part of the noontime pass that the external generator acted in opposition to an existing wind field since the Poynting flux was greater than the estimate of Joule heating from the electric field measurement alone (i.e., from ΣpE²). In the course of deriving Poynting's theorem for the geophysical case we also present a proof that ground magnetometer systems respond primarily to the Hall current which does not depend upon geometric cancellation between the field generated by Pedersen and field‐aligned currents.
Interstellar pickup protons at pressure‐balanced structures
Authors: Isenberg Philip A.
Published: February 2008

A recent attempt to measure the presence of interstellar pickup protons in the distant solar wind through their effects on the variations within pressure‐balanced structures found no evidence of these particles (Burlaga et al., 1990). That study concluded that the pickup protons, expected to be correlated with the solar wind density through the charge exchange ionization process, had become smeared in the radial direction. The resulting constant pressure rendered these particles undetectable by the analysis used. This paper presents an improved analysis which takes into account the cooling of these particles in the expanding solar wind. This improvement does not change the conclusions of the previous work. The possibility that quasi‐linear perpendicular diffusion is responsible for the inferred smearing across field lines is then investigated. It is shown that this mechanism can easily produce the required transport over the radial dimension of such a structure.
Some transient aspects of tidal propagation
Authors: Vial François , Forbes Jeffrey M. , Miyahara Saburo
Published: February 2008

The effects of transient forcing on the structure of some tidal modes are investigated using a time‐dependent numerical model. After presentation of the numerical scheme, some of the main features of tidal field variations are presented. The simulated tidal structures are interpreted as consisting of beats between tidal modes and transient waves near tidal periods. From these simulations, several types of information are obtained. Vertical group velocities are calculated and compared with those computed using the analytical expressions of Richmond (1975). Several possible definitions of the setup time are given, and the results from our model calculations are compared with those obtained by Bernard (1981). We found that the (2, 2) setup time is longer (several weeks) than the (1, 1) setup time, contrary to the Bernard conclusions. From these setup time estimates, some conclusions regarding the interpretation of observations and comparisons with steady state model calculations are drawn. Finally, similar results obtained for a two‐dimensional gravity wave are analyzed to clarify further basic mechanisms acting on tidal structure variations induced by transient forcing.
A finite difference solution of the polar electrojet current mapping boundary value problem
Authors: Werner D. H. , Ferraro A. J.
Published: February 2008

An investigation is made of how the polar electrojet currents and associated electric fields map down to the ground. The boundary value problem which characterizes the downward mapping of the electrojet current will be formulated using potential theory. The electrojet current is represented by a simple Cowling model in which the geomagnetic field is vertical. A numerical solution to the electrojet mapping boundary value problem is obtained via a finite difference technique. This model is employed to study the downward mapping of the polar electrojet current during intense magnetic storms occurring under sunspot maximum daytime conditions. Results of this analysis suggest that as the current maps down through the D region, from an electrojet source in the E region, it is being attenuated as well as rotated. The rotation, however, is not present at altitudes below the D region. A possible application of electrojet mapping theory to the interpretation of high‐latitude ionospheric modification data taken during polar electrojet events is discussed.
A search for parallel electric fields by observing secondary electrons and photoelectrons in the low‐altitude auroral zone
Authors: Fung Shing F. , Hoffman R. A.
Published: February 2008

The high sensitivities of the auroral secondary electron and atmospheric photoelectron spectra (<100 eV) to weak parallel dc electric fields make the particle distributions ideal for locating the lower boundary to the auroral electrostatic potential structures, which are often regarded as providing the mechanism responsible for the acceleration of auroral particles. The effects of weak parallel electric fields on the differential spectra of the low‐energy electrons observed in inverted‐V events are demonstrated with a set of heuristic model calculations. The spectral variations as a function of altitude of these electron populations in inverted‐V events observed by the Dynamics Explorer 2 spacecraft are examined separately for events connected to dark and sunlit local atmospheres. By comparing the altitude dependence of the observed spectra with the model calculations, we show that there can be no more than a 2‐volt potential drop on average between 400 and 900 km altitudes, corresponding to a distributed parallel dc electric field of less than 4 µV/m under the inverted‐V electron precipitation regions. Isotropy of the photoelectrons in inverted‐V events is also found to extend beyond the topside ionosphere, in accordance with the existence of a potential structure above the satellite. Statistical results on the spectral dependence of the secondary electrons on the inverted‐V primary beam parameters are also presented.
Microscale structure of the interplanetary medium and solar wind control of the time lags in the auroral zone geomagnetic response
Authors: Hruška A. , Wilson Margaret D.
Published: February 2008

While the level of auroral zone geomagnetic activity, as measured by the AE index, is determined by the value of the southward component, Bs, of the interplanetary magnetic field (IMF), the delay in the geomagnetic response is modified by the microscale fluctuations of the IMF vector B. The fluctuations are characterized by the square root σz of the variance of the solar magnetospheric (SM) z component of B. For extreme values of Bs(Bs > 5 nT and Bs = 0) the geomagnetic disturbances associated with small values of σz last longer than those associated with large σz. Conversely, for other values of Bs, the magnetosphere responds to the quasi‐stationary interplanetary conditions with a shorter delay than to the time dependent solar wind conditions. Autocorrelations of the solar wind (SW), parameters evaluated for various time lags are always stronger when the initial value of σz is small than when it is large. Analysis of the autocorrelations and of the geomagnetic responses corresponding to them suggests that, for positive but not extremely large values of Bs, the temporal fluctuations of B trigger the internal magnetospheric (or the SW‐magnetospheric coupling) processes which increase the observed time lags in the auroral zone geomagnetic activity. The value of σz is the SW parameter indicating whether the magnetosphere responds to SW conditions almost immediately (within less than ∼1 hour) or whether the magnetospheric response is more gradual and is delayed for another ∼1 to ∼4 hours. The data analyzed in this study indicate the existence of magnetospheric processes delaying the geomagnetic response to the SW conditions for Bs = 0 but they do not allow us to draw conclusions on the effects of σz when Bs is extremely high or equal to zero. Future short‐term forecasts of geomagnetic activity are likely to be based on the SW data obtained from an upwind located satellite and appropriate adjustments of the forecasts are in order to account for the effects of the fluctuations.