bluuebunny/crossref_metadata_2025 huggingface dataset:
Parathyroid risk in total thyroidectomy for bilateral, benign, multinodular goitre: report of 351 surgical cases
Authors: Page C , Strunski V
Published: March 2007

Aims: To evaluate the risk of hypocalcaemia (transient or permanent) after total thyroidectomy for bilateral, benign, multinodular goitre, the frequency and impact of unintentional parathyroidectomy, and the value of parathyroid gland autotransplantation during thyroid surgery.

Materials and methods: This was a retrospective study of 351 surgical patients who had undergone total thyroidectomy for bilateral, benign, multinodular goitre over a seven-year period. The primary endpoint was serum calcium concentration immediately post-operatively and during follow up. Normal serum calcium concentration was defined as 2 mmol/l. Parathyroid data were collected during surgery and histological examination.

Results: In 62 per cent of cases, no hypocalcaemia had been observed after surgery. In 35 per cent of cases, transient hypocalcaemia had been observed after surgery. In 3 per cent of cases, chronic hypocalcaemia had been present six months after surgery. Permanent hypoparathyroidism had been diagnosed two years after surgery in 1.4 per cent of cases. Unintentional parathyroidectomy had been detected in 5.2 per cent of cases. Parathyroid gland autotransplantation had been performed in 7 per cent of cases during surgery.

Conclusion: Permanent hypoparathyroidism is rare, although transient hypoparathyroidism occurs relatively frequently. Unintentional parathyroidectomy and parathyroid gland autotransplantation do not affect serum calcium levels.
Future People, Involuntary Medical Treatment in Pregnancy and the Duty of Easy Rescue
Authors: SAVULESCU JULIAN
Published: March 2007

I argue that pregnant women have a duty to refrain from behaviours (e.g. taking illicit drugs) or to allow certain acts to be done to them (e.g. caesarean section) for the sake of their foetus if the foetus has a reasonable chance of living and being in a harmed state if the woman does not refrain from those behaviours or allow those things to be done to her. There is a proviso: that her refraining from acting or allowing acts to be performed upon her does not significantly harm her. This duty does not presuppose that the foetus is a person. It is grounded on principles of respect for the interests of sentient beings and prevention of harm to future individuals. I give an argument for a general duty of easy rescue.
Respecting Persons, Respecting Preferences
Authors: VALDMAN MIKHAIL
Published: March 2007

In this article, I argue that the state has a prima facie obligation to help its citizens satisfy their autonomous preferences. I argue that this obligation is grounded in the state's obligation to respect its citizens as persons, and that part of what is involved in respecting someone as a person is helping her satisfy her autonomous preferences. I argue that that which makes preferences autonomous is also that which makes them, and not their non-autonomous counterparts, worthy of respect. In addition, I reject other views of what makes preferences worthy of respect, in particular Ronald Dworkin's view that only preferences for one's own enjoyment of some goods or opportunities deserve political consideration. Finally, I consider the state's obligation towards immoral autonomous preferences, and I argue that the state's prima facie obligation to promote the satisfaction of autonomous preferences is quite strong.
Rational Choice, Changes in Values over Time, and Well-Being
Authors: MCKERLIE DENNIS
Published: March 2007

Sometimes we make decisions which affect our lives at times when we will hold values that are different from our values at the time the decision is made. What is the reasonable way to make such a choice? Some think we should accept a requirement of temporal neutrality and take both sets of values into account, others think we should decide on the strength of our present values, yet others think that in evaluating what will happen at that other time we should use the values that we will endorse at that time instead of our present values. These views see the problem as one about finding some attitude towards time itself that is distinctively rational. This article argues that these views are subject to serious objections. It suggests that instead we should think in terms of well-being. If a person approves of, or positively responds to, the way their life is going they will experience more well-being than if there is no positive response. The article explores the implications of a positive response condition on well-being for deciding what it is rational to do in cases involving changing goals.
Schultz's Sidgwick
Authors: SKELTON ANTHONY
Published: March 2007

Bart Schultz's Henry Sidgwick: Eye of the Universe is a welcome addition to the growing literature on Sidgwick. In this article, I direct my attention for the most part to one aspect of what Schultz says about Sidgwick's masterpiece, The Methods of Ethics, as well as to what he does not say about Sidgwick's illuminating but neglected work Practical Ethics. This article is divided into three sections. In the first, I argue that there is a problem with Schultz's endorsement of the view that Sidgwick's moral epistemology combines elements of both coherentism and foundationalism. In the second, I argue that Schultz has failed to do justice to Sidgwick's mature views in Practical Ethics. In the final section, I briefly say something about Schultz's suggestion that Sidgwick succumbed to both racism and dishonesty.
NEW RECORDS OF CONIFERS IN CAMBODIA AND LAOS
Authors: THOMAS P. , SENGDALA KHAMPHONE , LAMXAY VICHITH , KHOU EANGHOURT
Published: March 2007

Thirty-three conifer species are currently recorded from Vietnam, Laos and Cambodia. All species are recorded from Vietnam but only six have been recorded from Cambodia and nine from Laos. Recent botanical surveys have recorded one additional species from Cambodia and seven from Laos. New distributions within those countries have also been recorded. This paper discusses those records.
A NEW SPECIES OF BARLERIA (ACANTHACEAE) FROM OMAN
Authors: KNEES S. G. , LASER S. , MILLER A. G. , PATZELT A.
Published: March 2007

A new species of Barleria (Acanthaceae), Barleria samhanensis Knees, A.G.Mill. & A.Patzelt, is described from southern Oman and a provisional assessment of its conservation status is provided. Further support is given for the recognition of the summit of Jabal Samhan as a distinct floristic unit.
Research Revolution at Eversheds
Authors: Mancino Melanie
Published: March 2007

Melanie Mancino discusses the implementation of a firmwide research and enquiry service at national law firm Eversheds. It explains why the decision was made to centralise the service, and how this was achieved, and goes on to explore why it was important for standardisation to take place. It ends by looking at the process involved in introducing an electronic enquiry management system and provides a summary of basic functionality. The benefits of the new service for the both the firm and the IS team are also highlighted.
Visit to the Faculty of Law in the University of Jos, Nigeria
Authors: Power Gerry
Published: March 2007

Gerry Power was invited to go to the University of Jos in April 2006 to present workshops to the Law Faculty and other interested legal professionals on using the internet for legal research. He writes about his experiences in dealing with running online workshops whilst coping with electricity shortages and the incredible experience of Nigeria!
The Present and Future for Lawlinks
Authors: Raper Diane
Published: March 2007

Diane Raper describes the ongoing project at the University of Kent to upgrade the free Lawlinks portal established nearly ten years ago by Sarah Carter. The emphasis is on ensuring linking is working, establishing new links, and generally making the site more user-friendly, both to Kent law students and the outside world.
Magnetic structures in the heliosheath
Authors: Avinash K. , Zank G. P.
Published: March 2007

We propose a solitary wave model for small scale magnetic structures observed in the solar wind and more recently in the Voyager 1 observations of the heliosheath. The model is based on the recent, fully nonlinear theory of solitary waves by McKenzie et al. (2001, 2004). Our solutions i.e., magnetic holes, humps, trains of holes and humps, are strongly nonlinear (70 to 80% change in the magnetic field at the centre), propagate at large angles (>60°) to the mean magnetic field and are well approximated by Gaussians. The structures are almost pressure balanced with an anti‐correlation between the magnetic field and the plasma density, and no change in the magnetic vector across the structure. These features are consistent with observations of magnetic structures in the heliosheath.
Volcanic activity influenced by tectonic earthquakes: Static and dynamic stress triggering at Mt. Merapi
Authors: Walter T. R. , Wang R. , Zimmer M. , Grosser H. , Lühr B. , Ratdomopurbo A.
Published: March 2007

Mt. Merapi is one of the most dangerous volcanoes in Indonesia, located within the tectonically active region of south‐central Java. This study investigates how Mt. Merapi affected ‐ and was affected by ‐ nearby tectonic earthquakes. In 2001, a Mw6.3 earthquake occurred in conjunction with an increase in fumarole temperature at Mt. Merapi. In 2006, another Mw6.3 earthquake took place, concomitant with an increase of magma extrusion and pyroclastic flows. Here, we develop theoretical models to study the amount of stress transfer between the earthquakes and the volcano, showing that dynamic, rather than static, stress changes are likely responsible for the temporal and spatial proximity of these events. Our examination of the 2001 and 2006 events implies that volcanic activity at Mt. Merapi is influenced by stress changes related to remote tectonic earthquakes, a finding that is important for volcano hazard assessment in this densely inhabited area.
A numerical simulation study of dissolved organic carbon accumulation in the northern Adriatic Sea
Authors: Polimene L. , Pinardi N. , Zavatarelli M. , Allen J. I. , Giani M. , Vichi M.
Published: March 2007

A mechanistic explanation for the accumulation of dissolved organic carbon (DOC), observed in coastal seas such as the Northern Adriatic Sea, is proposed here on the basis of numerical simulations of the marine ecosystem dynamics carried out with a coupled biogeochemical‐circulation model. The biogeochemical model is based on the European Regional Seas Ecosystem Model (ERSEM) upgraded with a more detailed representation of the DOC‐bacteria interactions and resolving different level of DOC lability/refractivity. The circulation model is the Adriatic Sea implementation of the Princeton Ocean Model. The analysis of simulations confirms the important role of the Po river nutrient input on the ecosystem dynamics and highlights the presence of a strong across‐shelf trophic gradient that, affecting the Bacterial Growth Efficiency (BGE), could be a key factor for the DOC accumulation. The simulations show the importance of circulation features in modulating the exchanges between areas having different trophic structure such as the western coastal strip, strongly influenced by the Po river runoff, and the open sea areas in the centre of the northern Adriatic sub‐basin. The DOC produced in the high energy system of the Po runoff coastal strip, characterized by high BGE, is transported toward the open areas, which is a more oligotrophic environment with lower BGE. In this area the DOC turnover time is strongly increased giving rise to the DOC accumulation.
Role of Value Compatibility in it Adoption
Authors: Bunker Deborah , Kautz Karl-Heinz , Nguyen Anne Luu Thanh
Published: March 2007

Compatibility has been recognised as an important element in the adoption of IT innovations in organisations but as a concept it has been generally limited to technical or functional factors. Compatibility is also significant, however, with regard to value compatibility between the organisation, and the adopted IT innovation. We propose a framework to determine value compatibility analysing the organisation's and information system's structure, practices and culture, and explore the value compatibility of an organisation with its adopted self-service computer-based information system. A case study was conducted to determine the congruence of an organisation's value and IT value compatibility. This study found that there was a high correspondence in the organisational structure and practice dimensions; however, there were organisational culture disparities. The cultural disparities reflected the self-service acceptance and training issues experienced by the case organisation. These findings add insight into the problems experienced with value compatibility and the adoption of the information systems, and show the potential use of the proposed framework in the detection of such problems.
Near-adiabatic quench experiments on short YBa2Cu3O7−δ coated conductors
Authors: Wang X. , Trociewitz U. P. , Schwartz J.
Published: March 2007

Minimum quench energy and normal zone propagation velocity are measured on short YBa2Cu3O7−δ coated conductors in self-field at temperatures ranging from 40to77K. The sample is cooled via a cryocooler with a cryostat pressure of ∼10−4Pa, creating a nearly adiabatic environment. A normal zone is created by pulsing a heater that is attached to the sample surface with a thin layer of alumina-filled epoxy. The minimum quench energy is determined by identifying the minimum heater energy that creates a propagating normal zone, and the propagation velocity is determined from the time delay between voltage signals in voltage taps distributed along the length of the conductor. It is found that the minimum quench energy is on the order of 1J and the normal zone propagation velocity ranges from 1–40mm∕s. These results are compared to similar measurements on other coated conductor architectures and geometries and to the classical adiabatic quench propagation model.
Study of optical elastic scattering in a quasiperiodically poled LiTaO3 crystal
Authors: Xie Z. D. , Zhao G. , Xu P. , Gao Z. D. , Zhu S. N.
Published: March 2007

In this letter we report the experimental result on the study of light scattering in a one-dimensional quasiperiodically poled LiTaO3 crystal. The infrared scattering signal in the crystal was upconverted into visible band by sum frequency with incident light, forming a set of coaxial conical second harmonic beam with a quasiperiodic ratio at the radius. The quasi-phase-matching significantly enhanced such a nonlinear interaction. The angular distribution of scattering light in crystal was extracted from the experimental result. This reveals a possible application of quasiperiodic structure on the study of light scattering.
Efficient terahertz generation using trap-enhanced fields in semi-insulating photoconductors by spatially broadened excitation
Authors: Kim Dae Sin , Citrin D. S.
Published: March 2007

The combined effects of large trap-enhanced fields (TEFs) near the anode in semi-insulating photoconductors and enhanced terahertz emission by spatially nonuniform optical illumination are investigated using a self-consistent Poisson–Monte Carlo solver for the carrier transport. In addition, we distinguish self-consistently the screening contributions to the terahertz radiation associated with the Coulomb and radiation fields by incorporating the three-dimensional Maxwell equations into the solver. Efficient terahertz generation is obtained by reducing the impact of these screening effects, which are the main factors underlying the saturation of the terahertz radiation power, by exploiting an elliptical excitation aperture as eccentric as possible with the major axis parallel to the anode and lying to the maximum extent within the large TEF region that occurs within ∼5μm of the anode.
Multiferroic BiFeO3 thin films deposited on SrRuO3 buffer layer by rf sputtering
Authors: Zheng R. Y. , Gao X. S. , Zhou Z. H. , Wang J.
Published: March 2007

Sr Ru O 3 (SRO) acts as an effective buffer layer for growth of multiferroic BiFeO3 (BFO) thin films deposited on Pt∕TiO2∕SiO2∕Si substrates by radio frequency sputtering. Phase identification by using x-ray diffraction and texture studies by using atomic force microscopy show that the SRO buffer layer promotes crystallization and formation of the perovskite phase at lowered temperature. It significantly reduces the leakage current of multiferroic BFO films, giving rise to a much improved square ferroelectric hysteresis loop, in contrast to the poor loop for BFO on bare Pt∕TiO2∕SiO2∕Si substrate. A much enlarged remnant polarization (2Pr) of 144μC∕cm2 and a coercive field (Ec) of 386kV∕cm were obtained with the BFO thin film deposited on SRO∕Pt∕TiO2∕SiO2∕Si at 600°C. The BFO thin film with SRO buffer layer also shows a large nonvolatile polarization (ΔP=Psw−Pnsw) of 122μC∕cm2 at 20μs, which promises excellent performance for random access memories. Further interestingly, it exhibits little polarization fatigue up to 5×1010 switching cycles, at a relatively high voltage of 10V, although a notable degradation of polarization is shown at the low voltage of 6V, indicating weak domain pinning. The multiferroic thin film demonstrates a weak ferromagnetic loop with a saturation magnetization (Ms) of 1.92emu∕cm3 and coercivity (Hc) of 325Oe.
Gaussian excitations model for glass-former dynamics and thermodynamics
Authors: Matyushov Dmitry V. , Angell C. Austen
Published: March 2007

We describe a model for the thermodynamics and dynamics of glass-forming liquids in terms of excitations from an ideal glass state to a Gaussian manifold of configurationally excited states. The quantitative fit of this three parameter model to the experimental data on excess entropy and heat capacity shows that “fragile” behavior, indicated by a sharply rising excess heat capacity as the glass transition is approached from above, occurs in anticipation of a first-order transition—usually hidden below the glass transition—to a “strong” liquid state of low excess entropy. The distinction between fragile and strong behavior of glass formers is traced back to an order of magnitude difference in the Gaussian width of their excitation energies. Simple relations connect the excess heat capacity to the Gaussian width parameter, and the liquid-liquid transition temperature, and strong, testable, predictions concerning the distinct properties of energy landscape for fragile liquids are made. The dynamic model relates relaxation to a hierarchical sequence of excitation events each involving the probability of accumulating sufficient kinetic energy on a separate excitable unit. Super-Arrhenius behavior of the relaxation rates, and the known correlation of kinetic with thermodynamic fragility, both follow from the way the rugged landscape induces fluctuations in the partitioning of energy between vibrational and configurational manifolds. A relation is derived in which the configurational heat capacity, rather than the configurational entropy of the Adam–Gibbs equation, controls the temperature dependence of the relaxation times, and this gives a comparable account of the experimental observations without postulating a divergent length scale. The familiar coincidence of zero mobility and Kauzmann temperatures is obtained as an approximate extrapolation of the theoretical equations. The comparison of the fits to excess thermodynamic properties of laboratory glass formers, and to configurational thermodynamics from simulations, reveals that the major portion of the excitation entropy responsible for fragile behavior resides in the low-frequency vibrational density of states. The thermodynamic transition predicted for fragile liquids emerges from beneath the glass transition in case of laboratory water and the unusual heat capacity behavior observed for this much studied liquid can be closely reproduced by the model.
One-dimensional arrays of superconducting quantum interference devices as magnetic-field-tuned superconducting detectors
Authors: Kuo Watson , Wu C. S. , Shyu J. H. , Chen C. D.
Published: March 2007

This study experimentally demonstrates a superconducting detector that can be switched for charge signal and superconducting phase signal detection by tuning a magnetic field. In zero magnetic field, the one-dimensional array of superconducting quantum interference devices exhibits superconducting coherency and is phase sensitive. The array may become insulating and charge sensitive when a small perpendicular magnetic field is applied.
Estimation of line tension and contact angle from heterogeneous nucleation experimental data
Authors: Hienola A. I. , Winkler P. M. , Wagner P. E. , Vehkamäki H. , Lauri A. , Napari I. , Kulmala M.
Published: March 2007

Using the classical nucleation theory corrected with line tension and experimental data of heterogeneous nucleation of n-nonane, n-propanol, and their mixture on silver particles of three different sizes, the authors were able to estimate the line tensions and the microscopic contact angles for the above mentioned systems. To do this they applied generalized Young’s equation for the line tension and calculated the interfacial tensions using Li and Neumann's equation [Adv. Colloid Interface Sci. 39, 299 (1992)]. It has been found that, for both unary and binary systems, the line tension is negative and the resulting microscopic contact angle derived from experimental nucleation data is most of the time larger than the macroscopic one. This is in contrast to earlier studies where the influence of line tension has not been accounted for. The values of the three phase contact line tension obtained in this way are of the same order of magnitude as the estimations for other systems reported in literature. The line tension effect also decreases considerably the nucleation barrier.
Cooperative polymer dynamics under nanoscopic pore confinements probed by field-cycling NMR relaxometry
Authors: Fatkullin Nail , Kausik Ravinath , Kimmich Rainer
Published: March 2007

Reptational dynamics of bulk polymer chains on a time scale between the Rouse mode relaxation time and the so-called disengagement time is not compatible with the basic thermodynamic law of fluctuations of the number of segments in a given volume. On the other hand, experimental field-cycling NMR relaxometry data of perfluoropolyether melts confined in Vycor, a porous silica glass of nominal pore dimension of 4nm, closely display the predicted signatures for the molecular weight and frequency dependences of the spin-lattice relaxation time in this particular limit, namely T1∝M−1∕2ν1∕2. It is shown that this contradiction is an apparent one. In this paper a formalism is developed suggesting cooperative chain dynamics under nanoscopic pore confinements. The result is a cooperative reptational displacement phenomenon reducing the root-mean-squared displacement rate correspondingly but showing the same characteristic dependences as the ordinary reptation model. The tube diameter effective for cooperative reptation is estimated on this basis for the sample system under consideration and is found to be of the same order of magnitude as the nominal pore diameter of Vycor.
Photodissociation of vibrationally excited SH and SD radicals at 288 and 291nm: The S(D21) channel
Authors: Janssen Liesbeth M. C. , van der Loo Mark P. J. , Groenenboom Gerrit C. , Wu Shiou-Min , Radenović Dragana Č. , van Roij André J. A. , Garcia Ivan Anton , Parker David H.
Published: March 2007

Ultraviolet photodissociation of SH (XΠ2, υ″=2–7) and SD (XΠ2, υ″=3–7) has been studied at 288 and 291nm, using the velocity map imaging technique to probe the angular and speed distributions of the S(D21) products. Photodissociation cross sections for the AΣ+2←XΠ2(υ″) and Δ2←XΠ2(υ″) transitions have been obtained by ab initio calculations at the CASSCF-MRSDCI/aug-cc-pV5Z level of theory. Both the experimental and theoretical results show that SH/SD photodissociation from XΠ2 (υ″⩽7) proceeds via the repulsive wall of the AΣ+2 state. The angular distributions of S(D21) indicate that the dissociation approaches the sudden recoil limit of the AΣ+2 state, yielding strongly polarized fragments. The S(D21) atoms are predominantly produced with total electronic angular momentum perpendicular to the recoil axis.
Statistical analysis of fluctuations and noise-driven transport in particle-in-cell simulations of plasma turbulence
Authors: Holod I. , Lin Z.
Published: March 2007

The problem of discrete particle noise has been studied based on direct fluctuation measurements from gyrokinetic particle-in-cell simulations of stable plasmas. From the statistical analysis of electrostatic potential time evolution, the space-time correlation function has been measured. Fluctuation spectra have been constructed and analyzed in detail. Noise-driven transport is calculated using the quasilinear expression for the diffusion coefficient and the obtained noise spectrum. The theoretical value of electron heat conductivity shows good agreement with that measured in the simulation. It has been shown that for the realistic parameters in actual turbulence simulations, the noise-driven transport depends linearly on the entropy of the system. This study makes it possible to estimate and subtract the noise contribution to the total transport during turbulence simulations.
Conductance modulation by individual acceptors in Si nanoscale field-effect transistors
Authors: Ono Y. , Nishiguchi K. , Fujiwara A. , Yamaguchi H. , Inokawa H. , Takahashi Y.
Published: March 2007

The authors measured low-temperature (6–28K) conductance in nanoscale p-channel field-effect transistors lightly doped with boron. They observed a conductance modulation, which they ascribed to the trapping/detrapping of single holes by/from individual acceptors. The statistics of the appearance of the modulation in a few ten samples indicates that the number of acceptors is small, or even just one, suggesting that what the authors have observed is single-charge-transistor operation by a single-acceptor quantum dot.
Alloying induced degradation of the absorption edge of InAsxSb1−x
Authors: Bansal Bhavtosh , Dixit V. K. , Venkataraman V. , Bhat H. L.
Published: March 2007

In As x Sb 1 − x alloys show a strong bowing in the energy gap, the energy gap of the alloy can be less than the gap of the two parent compounds. The authors demonstrate that a consequence of this alloying is a systematic degradation in the sharpness of the absorption edge. The alloy disorder induced band-tail (Urbach tail) characteristics are quantitatively studied for InAs0.05Sb0.95.
Role of the electron blocking layer in the low-temperature collapse of electroluminescence in nitride light-emitting diodes
Authors: Grzanka S. , Franssen G. , Targowski G. , Krowicki K. , Suski T. , Czernecki R. , Perlin P. , Leszczyński M.
Published: March 2007

The low-temperature breakdown of the electroluminescence intensity (ELI) of blue/violet InGaN-based light-emitting diodes (LEDs) is shown to be independent of the structural details of the LED active region. Instead, the presence of an electron blocking layer (EBL) plays a decisive role. The authors attribute the ELI collapse to the low-temperature hole-blocking properties of the EBL. However, removing the EBL leads to a much reduced ELI because of a disproportional increase of electron overflow processes, which shows that the presence of an EBL in blue/violet InGaN-based LEDs is still essential. Optimization of the EBL by means of Mg doping is discussed.
Features of phonon-limited electron mobility behavior of double-gate field-effect transistor with (111) Si surface channel
Authors: Yamamura Tsuyoshi , Sato Shingo , Omura Yasuhisa
Published: March 2007

One-dimensional self-consistent calculations and relaxation time approximations are used to study the phonon-limited electron mobility of the inversion layer at room temperature for ultrathin body Si (111) layers in single-gate (SG) and double-gate (DG) silicon-on-insulator (SOI) metal-oxide-semiconductor field-effect transistors (MOSFET’s). Assuming a 5-nm-thick SOI layer, it is shown that intravalley phonon scattering (acoustic-phonon scattering) in the DG SOI MOSFET inversion layer is strongly suppressed within a range of medium effective field (Eeff) values; DG SOI MOSFETs have higher phonon-limited electron mobility than SG SOI MOSFET’s. Many simulations strongly suggest that the suppression of acoustic-phonon scattering in a 5nm TSOI DG SOI MOSFET primarily stems from the reduction of the form factor (F00) value within medium Eeff values.
Numerical calculations of the total ac loss of Cu-stabilized YBa2Cu3O7−δ coated conductor with a ferromagnetic substrate
Authors: Nguyen Doan N. , Sastry Pamidi V. P. S. S. , Schwartz Justin
Published: March 2007

A numerical model is developed to calculate the total alternating-current (ac) loss of Cu-stabilized YBa2Cu3O7−δ (YBCO) coated conductors with a ferromagnetic substrate when carrying an alternating transport current in an ac background magnetic field. The time evolutions of current and magnetic field distributions along the width of the conductor are calculated by solving the one-dimensional Poisson equation for the magnetic vector potential. In addition to the ac loss dissipated in the superconducting layer, the ferromagnetic loss in the substrate and eddy current loss in the Cu stabilizer are also modeled. In the calculations, the superconducting voltage-current behavior is assumed to follow a power law. The model is capable of addressing other practical aspects of YBCO conductors, including the field dependence of the critical current density, and n value, and nonuniformities in the conductor. The magnetic shielding of the ferromagnetic substrate, however, was ignored in the calculations. Numerical results are compared with analytical and experimental results for some special cases.
Pleiotrophin is a neurotrophic factor for spinal motor neurons
Authors: Mi Ruifa , Chen Weiran , Höke Ahmet
Published: March 2007

Regeneration in the peripheral nervous system is poor after chronic denervation. Denervated Schwann cells act as a “transient target” by secreting growth factors to promote regeneration of axons but lose this ability with chronic denervation. We discovered that the mRNA for pleiotrophin (PTN) was highly up-regulated in acutely denervated distal sciatic nerves, but high levels of PTN mRNA were not maintained in chronically denervated nerves. PTN protected spinal motor neurons against chronic excitotoxic injury and caused increased outgrowth of motor axons out of the spinal cord explants and formation of “miniventral rootlets.” In neonatal mice, PTN protected the facial motor neurons against cell death induced by deprivation from target-derived growth factors. Similarly, PTN significantly enhanced regeneration of myelinated axons across a graft in the transected sciatic nerve of adult rats. Our findings suggest a neurotrophic role for PTN that may lead to previously unrecognized treatment options for motor neuron disease and motor axonal regeneration.
Retroviral insertional mutagenesis identifies RUNX genes involved in chronic myeloid leukemia disease persistence under imatinib treatment
Authors: Miething Cornelius , Grundler Rebekka , Mugler Claudia , Brero Simone , Hoepfl Josef , Geigl Jochen , Speicher Michael R. , Ottmann Oliver , Peschel Christian , Duyster Justus
Published: March 2007

The kinase inhibitor imatinib mesylate targeting the oncoprotein Bcr-Abl has revolutionized the treatment of chronic myeloid leukemia (CML). However, even though imatinib successfully controls the leukemia in chronic phase, it seems not to be able to cure the disease, potentially necessitating lifelong treatment with the inhibitor under constant risk of relapse. On a molecular level, the cause of disease persistence is not well understood. Initial studies implied that innate features of primitive progenitor cancer stem cells may be responsible for the phenomenon. Here, we describe an assay using retroviral insertional mutagenesis (RIM) to identify genes contributing to disease persistence
in vivo
. We transplanted mice with bone marrow cells retrovirally infected with the Bcr-Abl oncogene and subsequently treated the animals with imatinib to select for leukemic cells in which the proviral integration had affected genes modulating the imatinib response. Southern blot analysis demonstrated clonal outgrowth of cells carrying similar integration sites. Candidate genes located near the proviral insertion sites were identified, among them the transcription factor
RUNX3
. Proviral integration near the
RUNX3
promoter induced RUNX3 expression, and Bcr-Abl-positive cell lines with stable or inducible expression of RUNX1 or RUNX3 were protected from imatinib-induced apoptosis. Furthermore, imatinib treatment selected for RUNX1-expressing cells
in vitro
and
in vivo
after infection of primary bone marrow cells with Bcr-Abl and RUNX1. Our results demonstrate the utility of RIM for probing molecular modulators of targeted therapies and suggest a role for members of the
RUNX
transcription factor family in disease persistence in CML patients.
Mineralocorticoid receptor overexpression in forebrain decreases anxiety-like behavior and alters the stress response in mice
Authors: Rozeboom Aaron M. , Akil Huda , Seasholtz Audrey F.
Published: March 2007

Although numerous stress-related molecules have been implicated in vulnerability to psychiatric illness, especially major depression and anxiety disorders, the role of the brain mineralocorticoid receptor (MR) in stress, depression, and affective function is not well defined. MR is a steroid hormone receptor that detects circulating glucocorticoids with high affinity and has been primarily implicated in controlling their basal level and circadian rhythm. To specifically address the role of MR in hypothalamic-pituitary-adrenal axis activity and anxiety-related behaviors, we generated transgenic mice with increased levels of MR in the forebrain (MRov mice) by using the forebrain-specific calcium/calmodulin-dependent protein kinase II α promoter to direct expression of MR cDNA. A mild but chronic elevation in forebrain MR results in decreased anxiety-like behavior in both male and female transgenic mice. Female MRov mice also exhibit a moderate suppression of the corticosterone response to restraint stress. Increased forebrain MR expression alters the expression of two genes associated with stress and anxiety, leading to a decrease in the hippocampal glucocorticoid receptor (GR) and an increase in serotonin receptor 5HT-1a, consistent with the decreased anxiety phenotype. These data suggest that the functions of forebrain MR may overlap with GR in hypothalamic-pituitary-adrenal axis regulation, but they dissociate significantly from GR in the modulation of affective responses, with GR overexpression increasing anxiety-like behavior and MR overexpression dampening it. These findings point to the importance of the MR:GR ratio in the control of emotional reactivity.
Structure and reactivity of LpxD, the
N
-acyltransferase of lipid A biosynthesis
Authors: Buetow Lori , Smith Terry K. , Dawson Alice , Fyffe Stewart , Hunter William N.
Published: March 2007

The external layer of the Gram-negative bacterial outer membrane is primarily composed of a protective, selectively permeable LPS. The biosynthesis of LPS relies on UDP-3-
O
-acyl-glucosamine
N
-acyltransferase (LpxD), which transfers 3-hydroxy-arachidic acid from acyl carrier protein to the 2′ amine of UDP-3-
O
-myristoyl glucosamine in
Chlamydia trachomatis
. Our crystallographic study reveals that LpxD is a homotrimer, each subunit of which is constructed from a novel combination of an N-terminal uridine-binding domain, a core lipid-binding domain, and a C-terminal helical extension. Highly conserved residues dominate nucleotide binding. Phe-43 and Tyr-49 form π-stacking interactions with uracil, and Asn-46 and His-284 form hydrogen bonds with the phosphate groups. These interactions place the glucosamine moiety at the catalytic center formed by two adjacent subunits. Here His-247 and His-284 contribute to a mechanism involving nucleophilic attack by the amine of one substrate on the carbonyl carbon of an acyl carrier protein thioester conjugate. Serendipitously, our study reveals a fatty acid (FA) binding groove near the catalytic center. MS elucidated the presence of a FA mixture binding to LpxD, with palmitic acid the most prevalent. The placement of UDP-
N
-acetylglucosamine and the FA provides details of
N
-acyltransferase ligand interactions and allows for a description of structure and reactivity at an early stage of LPS assembly.
Functional residues serve a dominant role in mediating the cooperativity of the protein ensemble
Authors: Liu Tong , Whitten Steven T. , Hilser Vincent J.
Published: March 2007

Conformational fluctuations in proteins have emerged as a potentially important aspect of biological function, although the precise relationship and the implications have yet to be fully explored. Numerous studies have reported that the binding of ligand can influence fluctuations. However, the role of the binding site in mediating these fluctuations is not known. Of particular interest is whether in addition to serving as structural scaffolds for recognition and catalysis, active-site residues may also play a role in modulating the cooperative network. To address this question, we employ an experimentally validated ensemble-based description of proteins to elucidate the extent to which perturbations at different sites can influence the cooperative network in the protein. Applying this method to a database of test proteins, it is found statistically that binding sites are located in regions most able to affect the cooperative network, even for cooperative interactions between residues distant to the binding sites. This indicates that the conformational manifold under native conditions is determined by the network of cooperative interactions within the protein and suggests that proteins have evolved to use these conformational fluctuations in carrying out their functions. Furthermore, because the energetic coupling pattern calculated for each protein is robust and relatively insensitive to sequence, these studies further suggest that binding sites evolved in regions of the protein that are inherently poised to take advantage of the fluctuations in the native structure.
Network activity-independent coordinated gene expression program for synapse assembly
Authors: Valor Luis M. , Charlesworth Paul , Humphreys Lawrence , Anderson Chris N. G. , Grant Seth G. N.
Published: March 2007

Global biological datasets generated by genomics, transcriptomics, and proteomics provide new approaches to understanding the relationship between the genome and the synapse. Combined transcriptome analysis and multielectrode recordings of neuronal network activity were used in mouse embryonic primary neuronal cultures to examine synapse formation and activity-dependent gene regulation. Evidence for a coordinated gene expression program for assembly of synapses was observed in the expression of 642 genes encoding postsynaptic and plasticity proteins. This synaptogenesis gene expression program preceded protein expression of synapse markers and onset of spiking activity. Continued expression was followed by maturation of morphology and electrical neuronal networks, which was then followed by the expression of activity-dependent genes. Thus, two distinct sequentially active gene expression programs underlie the genomic programs of synapse function.
VEGF is an essential mediator of the neurogenic and behavioral actions of antidepressants
Authors: Warner-Schmidt Jennifer L. , Duman Ronald S.
Published: March 2007

The neural mechanisms underlying the cellular and behavioral responses to antidepressants are not yet known. Up-regulation of growth factors and adult neurogenesis suggest a role for one or more of these factors in the action of antidepressants. One candidate of interest is vascular endothelial growth factor (VEGF), which was initially characterized for its role in angiogenesis, but also exerts direct mitogenic effects on neural progenitors
in vitro
. Results of this study demonstrate that VEGF is induced by multiple classes of antidepressants at time points consistent with the induction of cell proliferation and therapeutic action of these treatments. We find that VEGF signaling through the Flk-1 receptor is required for antidepressant-induced cell proliferation. We also show that VEGF-Flk-1 signaling is required and sufficient for behavioral responses in two chronic and two subchronic antidepressant models. Taken together, these studies identify VEGF and VEGF-Flk-1 signaling as mediators of antidepressant actions and potential targets for therapeutic intervention.
The changing carbon cycle at Mauna Loa Observatory
Authors: Buermann Wolfgang , Lintner Benjamin R. , Koven Charles D. , Angert Alon , Pinzon Jorge E. , Tucker Compton J. , Fung Inez Y.
Published: March 2007

The amplitude of the CO
2
seasonal cycle at the Mauna Loa Observatory (MLO) increased from the early 1970s to the early 1990s but decreased thereafter despite continued warming over northern continents. Because of its location relative to the large-scale atmospheric circulation, the MLO receives mainly Eurasian air masses in the northern hemisphere (NH) winter but relatively more North American air masses in NH summer. Consistent with this seasonal footprint, our findings indicate that the MLO amplitude registers North American net carbon uptake during the warm season and Eurasian net carbon release as well as anomalies in atmospheric circulation during the cold season. From the early 1970s to the early 1990s, our analysis was consistent with that of Keeling
et al.
[Keeling CD, Chin JFS, Whorf TP (1996)
Nature
382:146–149], suggesting that the increase in the MLO CO
2
amplitude is dominated by enhanced photosynthetic drawdown in North America and enhanced respiration in Eurasia. In contrast, the recent decline in the CO
2
amplitude is attributed to reductions in carbon sequestration over North America associated with severe droughts from 1998 to 2003 and changes in atmospheric circulation leading to decreased influence of Eurasian air masses. With the return of rains to the U.S. in 2004, both the normalized difference vegetation index and the MLO amplitude sharply increased, suggesting a return of the North American carbon sink to more normal levels. These findings indicate that atmospheric CO
2
measurements at remote sites can continue to play an important role in documenting changes in land carbon flux, including those related to widespread drought, which may continue to worsen as a result of global warming.
Role of RNA polymerase IV in plant small RNA metabolism
Authors: Zhang Xiaoyu , Henderson Ian R. , Lu Cheng , Green Pamela J. , Jacobsen Steven E.
Published: March 2007

In addition to the three RNA polymerases (RNAP I–III) shared by all eukaryotic organisms, plant genomes encode a fourth RNAP (RNAP IV) that appears to be specialized in the production of siRNAs. Available data support a model in which dsRNAs are generated by RNAP IV and RNA-dependent RNAP 2 (RDR2) and processed by DICER (DCL) enzymes into 21- to 24-nt siRNAs, which are associated with different ARGONAUTE (AGO) proteins for transcriptional or posttranscriptional gene silencing. However, it is not yet clear what fraction of genomic siRNA production is RNAP IV-dependent, and to what extent these siRNAs are preferentially processed by certain DCL(s) or associated with specific AGOs for distinct downstream functions. To address these questions on a genome-wide scale, we sequenced ≈335,000 siRNAs from wild-type and RNAP IV mutant
Arabidopsis
plants by using 454 technology. The results show that RNAP IV is required for the production of >90% of all siRNAs, which are faithfully produced from a discrete set of genomic loci. Comparisons of these siRNAs with those accumulated in
rdr2
and
dcl2 dcl3 dcl4
and those associated with AGO1 and AGO4 provide important information regarding the processing, channeling, and functions of plant siRNAs. We also describe a class of RNAP IV-independent siRNAs produced from endogenous single-stranded hairpin RNA precursors.
Paradoxical influence of hippocampal neurogenesis on working memory
Authors: Saxe Michael D. , Malleret Gaël , Vronskaya Svetlana , Mendez Indira , Garcia A. Denise , Sofroniew Michael V. , Kandel Eric R. , Hen René
Published: March 2007

To explore the function of adult hippocampal neurogenesis, we ablated cell proliferation by using two independent and complementary methods: (
i
) a focal hippocampal irradiation and (
ii
) an inducible and reversible genetic elimination of neural progenitor cells. Previous studies using these methods found a weakening of contextual fear conditioning but no change in spatial reference memory, suggesting a supportive role for neurogenesis in some, but not all, hippocampal-dependent memory tasks. In the present study, we examined hippocampal-dependent and -independent working memory using different radial maze tasks. Surprisingly, ablating neurogenesis caused an improvement of hippocampal-dependent working memory when repetitive information was presented in a single day. These findings suggest that adult-born cells in the dentate gyrus have different, and in some cases, opposite roles in distinct types of memory.
Folate biofortification of tomato fruit
Authors: Díaz de la Garza Rocío I. , Gregory Jesse F. , Hanson Andrew D.
Published: March 2007

Folate deficiency leads to neural tube defects and other human diseases, and is a global health problem. Because plants are major folate sources for humans, we have sought to enhance plant folate levels (biofortification). Folates are synthesized from pteridine,
p
-aminobenzoate (PABA), and glutamate precursors. Previously, we increased pteridine production in tomato fruit up to 140-fold by overexpressing GTP cyclohydrolase I, the first enzyme of pteridine synthesis. This strategy increased folate levels 2-fold, but engineered fruit were PABA-depleted. We report here the engineering of fruit-specific overexpression of aminodeoxychorismate synthase, which catalyzes the first step of PABA synthesis. The resulting fruit contained an average of 19-fold more PABA than controls. When transgenic PABA- and pteridine-overproduction traits were combined by crossing, vine-ripened fruit accumulated up to 25-fold more folate than controls. Folate accumulation was almost as high (up to 15-fold) in fruit harvested green and ripened by ethylene-gassing, as occurs in commerce. The accumulated folates showed normal proportions of one-carbon forms, with 5-methyltetrahydrofolate the most abundant, but were less extensively polyglutamylated than controls. Folate concentrations in developing fruit did not change in controls, but increased continuously throughout ripening in transgenic fruit. Pteridine and PABA levels in transgenic fruit were >20-fold higher than in controls, but the pathway intermediates dihydropteroate and dihydrofolate did not accumulate, pointing to a flux constraint at the dihydropteroate synthesis step. The folate levels we achieved provide the complete adult daily requirement in less than one standard serving.