bluuebunny/crossref_metadata_2025 huggingface dataset:
Optical and electrical control of slow light in p-doped and intrinsic quantum-dot electroabsorbers
Authors: Kondratko Piotr Konrad , Chang Shu-Wei , Su Hui , Chuang Shun-Lien
Published: June 2007

Room temperature p-doped and intrinsic quantum-dot semiconductor electroabsorption modulator is utilized as an optical group delay. Electrical (reverse voltage and forward current, below transparency) and optical controllable delay is realized by means of counterpropagating coherent population oscillation. Because of carrier dynamics, the experimental observations show bandwidth increase with reverse voltage and dependence of group delay on background absorption. Moreover, experimental observations show maximum group delay at a particular pump intensity, which is attributed to inhomogeneous contributions and saturation effects in quantum dots.
Strong terahertz absorption bands in a scaled plasmonic crystal
Authors: Teperik T. V. , García de Abajo F. J. , Popov V. V. , Shur M. S.
Published: June 2007

The authors show the existence of strong absorption bands at terahertz frequencies in scaled plasmonic crystals composed of a periodic arrangement of two-dimensional electron-gas shells. The absorption bands appear as a result of the excitation of plasmon modes supported by the shells and can be tuned throughout the entire terahertz spectral region by varying the electron-gas density in the shells. These plasmonic crystals exhibit promising properties enabling their applications as tunable terahertz filters, absorbers, and thermally activated sources.
Probing electronic excitations in organic light-emitting diodes via Raman scattering
Authors: Arif M. , Guha S. , Tsami A. , Scherf U.
Published: June 2007

The authors present Raman scattering studies from ethyl-hexyl substituted polyfluorene (PF)-based light-emitting diodes in the presence of injected and photogenerated charge carriers. The Raman background systematically increases with increased charge density and the Raman peaks exhibit asymmetric line shapes characteristic of a Breit-Wigner-Fano (BWF) resonance, indicating interference effects between the electronic continuum and phonons. A complete BWF line shape analysis of the intraring stretch mode at 1605cm−1 is provided. These results are compared with p-doped PF; by increasing the doping concentration, it is seen that the center of the electronic continuum lies at ∼0.2eV.
Multiferroic properties and dielectric relaxation of BiFeO3∕Bi3.25La0.75Ti3O12 double-layered thin films
Authors: Huang Fengzhen , Lu Xiaomei , Lin Weiwei , Cai Wei , Wu Xiumei , Kan Yi , Sang Hai , Zhu Jinsong
Published: June 2007

Bi Fe O 3  (BFO)∕Bi3.25La0.75Ti3O12 (BLT) films were prepared on (111) Pt∕Ti∕SiO2∕Si substrates via metal organic decomposition method. The multiferroic and dielectric properties of the films were studied. It was found that the ferroelectric polarization and dielectric constant of the films were enhanced by introducing BLT as a barrier layer between BFO and Pt bottom electrode, while the ferromagnetism of BFO was not influenced. More interestingly, the films showed dielectric relaxor behavior, and the possible causes of which were discussed.
Optimization of nano-magneto-optic sensitivity using dual dielectric layer enhancement
Authors: Wang S. , Barman A. , Schmidt H. , Maas J. D. , Hawkins A. R. , Kwon S. , Harteneck B. , Cabrini S. , Bokor J.
Published: June 2007

We discuss maximization of the sensitivity of magneto-optical detection of single nanomagnets. We show that a combination of optimized dielectric coating on the magnets with an antireflection coated substrate can increase the areal magneto-optic sensitivity by about three orders of magnitude in the deep nanometer range. A dual layer nanofabrication process is developed to implement this approach, and magnetization switching of single nickel nanomagnets with 50nm diameter is demonstrated.
Subwavelength resolution with a negative-index metamaterial superlens
Authors: Aydin Koray , Bulu Irfan , Ozbay Ekmel
Published: June 2007

Negative-index metamaterials are candidates for imaging objects with sizes smaller than a half-wavelength. The authors report an impedance-matched, low loss negative-index metamaterial superlens that is capable of resolving subwavelength features of a point source with a 0.13λ resolution, which is the highest resolution achieved by a negative-index metamaterial. By separating two point sources with a distance of λ∕8, they were able to detect two distinct peaks on the image plane. They also showed that the metamaterial based structure has a flat lens behavior.
Extended conjugation and donor-acceptor substitution to improve the third-order optical nonlinearity of small molecules
Authors: May Joshua C. , Biaggio Ivan , Bures Filip , Diederich François
Published: June 2007

The authors use donor-acceptor substitution to increase the third-order polarizability γ of small cyanoethynylethene molecules by lowering the energy corresponding to the first optical transition. They identify a weak power-law dependence for γ depending on the number of conjugated electrons that separate the donor and acceptors (N1.5), which is the result of the two competing contributions that depend on the conjugation length: the energy separation of the ground and first excited states and the strength of the transition dipole matrix elements. The molecules are highly efficient with respect to their small masses and fall within a factor of 50 of the theoretical limit for centrosymmetric molecules, putting them among the best molecules measured to date.
Spin transport through multilayer graphene
Authors: Nishioka Masaya , Goldman A. M.
Published: June 2007

The magnetoresistance (MR) of Co/multilayer graphene/Co spin valve structures has been studied. A positive MR of up to 0.39% at 2K with switching at magnetic fields that are consistent with the magnetization orientations inferred from anisotropic MR data obtained for the Co contacts has been observed. The positive MR decreases with increasing excitation current and eventually changes sign. The positive MR decreases with increasing temperature, but the negative MR has no temperature dependence.
Reduction of optical damage in lithium niobate crystals by thermo-electric oxidization
Authors: Falk M. , Woike Th. , Buse K.
Published: June 2007

The impact of conventional and of electric-field enhanced thermal oxidization on photorefractive index changes in nominally undoped lithium niobate crystals is investigated. Light-induced birefringence changes are measured with a Senarmont compensator for various light intensities and for crystals after different oxidization treatments. It is shown that the conventional annealing in oxygen atmosphere suppresses the unwanted index changes by a factor of 5. However, thermo-electric oxidization leads to a suppression by one order of magnitude. This effect is attributed to a permanent lowering of the amount of photoexcitable charge carriers achieved by the thermo-electric oxidization treatment. Such oxidized crystals can be very useful for, e.g., second harmonic generation or optical parametric oscillation.
Nonlinearities and parametric amplification in superconducting coplanar waveguide resonators
Authors: Tholén Erik A. , Ergül Adem , Doherty Evelyn M. , Weber Frank M. , Grégis Fabien , Haviland David B.
Published: June 2007

Experimental investigations of the nonlinear properties of superconducting niobium coplanar waveguide resonators are reported. The nonlinearity due to a current dependent kinetic inductance of the center conductor is strong enough to realize bifurcation of the nonlinear oscillator. When driven with two frequencies near the threshold for bifurcation, parametric amplification with a gain of +22.4dB is observed.
Improved photostability of organic thin film transistors with tantalum oxide/poly(4-vinylphenol) double gate insulators
Authors: Zhao Yihua , Dong Guifang , Wang Liduo , Qiu Yong
Published: June 2007

In this letter, the authors investigated the photostability of pentacene organic thin film transistors (OTFTs) with Ta2O5 gate insulators. Under illumination, the threshold voltage shift of the Ta2O5-based OTFTs reached 5.51V. The obvious photoinstability was attributed to the electron trapping ability of the Ta2O5 film. To solve this problem, poly(4-vinylphenol) (PVP), a type of polymer with low trap density and high photostability was used to modify Ta2O5. It was found that OTFTs with Ta2O5∕PVP double gate insulators showed improved performance, and the voltage shift after illumination was greatly reduced to 0.04V.
Stable hydrogen sensors from AlGaN∕GaN heterostructure diodes with TiB2-based Ohmic contacts
Authors: Wang Hung-Ta , Anderson T. J. , Kang B. S. , Ren F. , Li Changzhi , Low Zhen-Ning , Lin Jenshan , Gila B. P. , Pearton S. J. , Osinsky A. , Dabiran Amir
Published: June 2007

The use of TiB2-based Ohmic contacts on Pt-gate AlGaN∕GaN heterostructure diode hydrogen sensors is shown to provide very stable operation for detection of 1% H2 in air under field conditions where temperature is allowed to vary. In contrast, the use of more conventional Ti∕Al∕Pt∕Au Ohmic contacts led to higher background variations in current that affect the ultimate detection threshold of the sensors. Combined with a differential pair geometry that compares current from an active diode with Pt-gate contact and a passive diode with Ti∕Au gate, the more stable TiB2-based Ohmic contacts reduce false alarms due to ambient temperature changes. The diodes exhibit a change in forward current of more than 1mA at 1.5V when 1% H2 is introduced into an air ambient.
Ultrafast hot electron relaxation time anomaly in InN epitaxial films
Authors: Tsai Tsong-Ru , Chang Chih-Fu , Gwo S.
Published: June 2007

Ultrafast carrier dynamics in InN epitaxial films was investigated by using femtosecond time-resolved pump-probe reflectivity measurements with a photon energy of 1.58eV. The hot electron relaxation time decreased with increasing electron density (n), measuring at n−0.5. The result was contradictory to what was expected from the hot phonon effect and the screening effect. The authors attributed this result to the important role played by electron-electron scattering in hot electron relaxation.
Extraordinary optical transmission with coaxial apertures
Authors: Orbons Shannon M. , Roberts Ann , Jamieson David N. , Haftel Michael I. , Schlockermann Carl , Freeman Darren , Luther-Davies Barry
Published: June 2007

Recently it has been predicted that “cylindrical” surface plasmons (CSP’s) on cylindrical interfaces of coaxial ring apertures produce a different form of extraordinary optical transmission that extends to ever increasing wavelengths as the dielectric ring narrows. This letter presents experimental confirmation of this CSP assisted extraordinary transmission. Nanoarrays of submicron coaxial apertures are fabricated in a thin silver film on a glass substrate and far-field transmission spectra are measured. The experimental spectrum is in close agreement with predictions from finite-difference time-domain simulations and CSP dispersion theory. The role of cylindrical surface plasmons in producing extraordinary transmission is thus confirmed.
Simulated and observed variability in ocean temperature and heat content
Authors: AchutaRao K. M. , Ishii M. , Santer B. D. , Gleckler P. J. , Taylor K. E. , Barnett T. P. , Pierce D. W. , Stouffer R. J. , Wigley T. M. L.
Published: June 2007

Observations show both a pronounced increase in ocean heat content (OHC) over the second half of the 20th century and substantial OHC variability on interannual-to-decadal time scales. Although climate models are able to simulate overall changes in OHC, they are generally thought to underestimate the amplitude of OHC variability. Using simulations of 20th century climate performed with 13 numerical models, we demonstrate that the apparent discrepancy between modeled and observed variability is largely explained by accounting for changes in observational coverage and instrumentation and by including the effects of volcanic eruptions. Our work does not support the recent claim that the 0- to 700-m layer of the global ocean experienced a substantial OHC decrease over the 2003 to 2005 time period. We show that the 2003–2005 cooling is largely an artifact of a systematic change in the observing system, with the deployment of Argo floats reducing a warm bias in the original observing system.
Probing nucleation, reverse annealing, and chaperone function along the reaction path of HIV-1 single-strand transfer
Authors: Zeng Yining , Liu Hsiao-Wei , Landes Christy F. , Kim Yoen Joo , Ma Xiaojing , Zhu Yongjin , Musier-Forsyth Karin , Barbara Paul F.
Published: June 2007

Reverse transcription of the HIV-1 genome involves several nucleic acid rearrangement steps that are catalyzed (chaperoned) by the nucleocapsid protein (NC), including the annealing of the transactivation response region (TAR) RNA of the genome to the complementary sequence (TAR DNA) in minus-strand strong-stop DNA. It has been extremely challenging to obtain unambiguous mechanistic details on the annealing process at the molecular level because of the kinetic involvement of a complex and heterogeneous set of nucleic acid/protein complexes of variable structure and variable composition. Here, we investigate the
in vitro
annealing mechanism using a multistep single-molecule spectroscopy kinetic method. In this approach, an immobilized hairpin is exposed to a multistep programmed concentration sequence of NC, model complementary targeted-oligonucleotides, and buffer-only solutions. The sequence controllably “drags” single immobilized TAR hairpins among the kinetic stable states of the reaction mechanism; i.e., reactants, intermediates, and products. This single-molecule spectroscopy method directly probes kinetic reversibility and the chaperone (catalytic) role of NC at various stages along the reaction sequence, giving access to previously inaccessible kinetic processes and rate constants. By employing target oligonucleotides for specific TAR regions, we kinetically trap and investigate structural models for putative nucleation complexes for the annealing process. The new results lead to a more complete and detailed understanding of the ability of NC to promote nucleic acid/nucleic acid rearrangement processes. This includes information on the ability of NC to chaperone “reverse annealing” in single-strand transfer and the first observation of partially annealed, conformational substates in the annealing mechanism.
Amyloidogenic potential of foie gras
Authors: Solomon Alan , Richey Tina , Murphy Charles L. , Weiss Deborah T. , Wall Jonathan S. , Westermark Gunilla T. , Westermark Per
Published: June 2007

The human cerebral and systemic amyloidoses and prion-associated spongiform encephalopathies are acquired or inherited protein folding disorders in which normally soluble proteins or peptides are converted into fibrillar aggregates. This is a nucleation-dependent process that can be initiated or accelerated by fibril seeds formed from homologous or heterologous amyloidogenic precursors that serve as an amyloid enhancing factor (AEF) and has pathogenic significance in that disease may be transmitted by oral ingestion or parenteral administration of these conformationally altered components. Except for infected brain tissue, specific dietary sources of AEF have not been identified. Here we report that commercially available duck- or goose-derived foie gras contains birefringent congophilic fibrillar material composed of serum amyloid A-related protein that acted as a potent AEF in a transgenic murine model of secondary (amyloid A protein) amyloidosis. When such mice were injected with or fed amyloid extracted from foie gras, the animals developed extensive systemic pathological deposits. These experimental data provide evidence that an amyloid-containing food product hastened the development of amyloid protein A amyloidosis in a susceptible population. On this basis, we posit that this and perhaps other forms of amyloidosis may be transmissible, akin to the infectious nature of prion-related illnesses.
Memory CD8+T cells are gatekeepers of the lymph node draining the site of viral infection
Authors: Xu Ren-Huan , Fang Min , Klein-Szanto Andres , Sigal Luis J.
Published: June 2007

It is uncertain how immunity protects against systemic viral diseases. Here, we demonstrate that in the absence of persistent virus, not only antibodies but also recall responses by long-lived memory CD8+T cells prevent mousepox, a disease caused by ectromelia virus, a close relative of the virus of human smallpox. Moreover, we show that to protect, recall CD8+T cells directly kill targets in the lymph node draining the primary site of infection thus curbing systemic viral spread. Therefore, our work provides the basis for a model where lymph nodes are not just organs where lymphocytes become activated and proliferate but also the sites where a major fight against virus spread takes place.
Transposition of the rice miniature inverted repeat transposable element
mPing
in
Arabidopsis thaliana
Authors: Yang Guojun , Zhang Feng , Hancock C. Nathan , Wessler Susan R.
Published: June 2007

An active miniature inverted repeat transposable element (MITE),
mPing
, was discovered by computer-assisted analysis of rice genome sequence. The
mPing
element is mobile in rice cell culture and in a few rice strains where it has been amplified to >1,000 copies during recent domestication. However, determination of the transposase source and characterization of the mechanism of transposition have been hampered by the high copy number of
mPing
and the presence of several candidate autonomous elements in the rice genome. Here, we report that
mPing
is active in
Arabidopsis thaliana
, where its transposition is catalyzed by three sources of transposase from rice: the autonomous
Ping
and
Pong
elements and by a cDNA derived from a
Ping
transcript. In addition to transposase, the product of a second element-encoded ORF of unknown function is also required for
mPing
transposition. Excision of
mPing
in
A. thaliana
is usually precise, and transposed copies usually insert into unlinked sites in the genome that are preferentially in or near genes. As such, this will be a valuable assay system for the dissection of MITE transposition and a potentially powerful tagging system for gene discovery in eukaryotes.
Scaling metabolic rate fluctuations
Authors: Labra Fabio A. , Marquet Pablo A. , Bozinovic Francisco
Published: June 2007

Complex ecological and economic systems show fluctuations in macroscopic quantities such as exchange rates, size of companies or populations that follow non-Gaussian tent-shaped probability distributions of growth rates with power-law decay, which suggests that fluctuations in complex systems may be governed by universal mechanisms, independent of particular details and idiosyncrasies. We propose here that metabolic rate within individual organisms may be considered as an example of an emergent property of a complex system and test the hypothesis that the probability distribution of fluctuations in the metabolic rate of individuals has a “universal” form regardless of body size or taxonomic affiliation. We examined data from 71 individuals belonging to 25 vertebrate species (birds, mammals, and lizards). We report three main results. First, for all these individuals and species, the distribution of metabolic rate fluctuations follows a tent-shaped distribution with power-law decay. Second, the standard deviation of metabolic rate fluctuations decays as a power-law function of both average metabolic rate and body mass, with exponents −0.352 and −1/4 respectively. Finally, we find that the distributions of metabolic rate fluctuations for different organisms can all be rescaled to a single parent distribution, supporting the existence of general principles underlying the structure and functioning of individual organisms.
Going all the way: how Hindawi became an open access publisher
Authors: PETERS Paul
Published: June 2007

As the Hindawi Publishing Corporation approaches its tenth anniversary, the author looks back at the history of Hindawi and examines a number of challenges that the company has faced over the past decade. These challenges include the rapid expansion of the company's workforce, the establishment of a standard editorial system for its journals, and the conversion of Hindawi's entire operation to an open access publication model. Although some of Hindawi's characteristics may not be common among other publishers, many of the challenges that Hindawi has faced are the result of recent developments within the scholarly publishing market that have implications for the entire industry.
The challenge of open access for university presses
Authors: THATCHER Sanford G.
Published: June 2007

University presses were founded in the late 19th century to help alleviate a problem of market failure, namely insufficient demand in the commercial marketplace to sustain a publishing operation on the basis of sales alone. Now, in the face of claims about another type of market failure – insufficient funds to sustain library subscriptions to STM journals – calls have come forth to change the economic model of publishing from sales‐based to grants‐based, offering the fruits of knowledge free to all users with an Internet connection. This paper examines both the challenges and the opportunities that the variants of ‘open access’ present to university presses, as they seek to fulfill their traditional mission of disseminating knowledge ‘far and wide’ while remaining sustainable as businesses.
Journal publishing systems: outsource or in‐house?
Authors: WARE Mark
Published: June 2007

This article describes a framework to help publishers decide whether they should develop and host their own proprietary online journal system, or whether they should outsource this activity. We also suggest a practical high‐level checklist for comparing journal systems.
From sailing boat to steamship: the role of the publisher in an open access environment
Authors: DE VRIES Saskia C. J.
Published: June 2007

The Internet has been a huge success in the academic world, as it makes it possible for academics to share and find research materials; open access has therefore become a fact of life for academic publishing. But what is the role of publishers in this new environment? The key functions of publishing – organizing peer review, editorial support, graphic design, marketing, and distribution of academic information – do not just disappear; publishers still have a role here, but they need to take a more service‐minded perspective. Academics still need to find ways to ensure the dissemination of their output; it is important that they realize that this will cost money, whether it is brought in‐house or outsourced. The IMISCOE project, on which Amsterdam University Press has recently embarked, offers an entirely new publishing model oriented towards online dissemination of academic research results, as well as in book form.
Amelioration of Carcinogen‐Induced Toxicity in Mice by Administration of a Potentized Homeopathic Drug, Natrum Sulphuricum 200
Authors: Bhattacharjee Nandini , Pathak Surajit , Khuda-Bukhsh Anisur Rahman
Published: June 2007

To examine if a potentized homeopathic drug, Natrum Sulphuricum 200 (Nat Sulph‐200) has protective potentials against hepatocarcinogenesis, liver tumors were induced in mice through chronic feeding of P‐dimethylaminoazobenzene (p‐DAB; initiator of hepatocarcinogenesis) and phenobarbital (PB; promoter). Mice were divided into five sub‐groups: fed normal low protein diet (Gr. I, normal control); fed normal low protein plus alcohol‐200 (vehicle of the homeopathic remedy) (Gr. II); fed diet mixed with 0.06% p‐DAB plus 0.05% PB (Gr. III); fed diet and carcinogens like Gr.III, plus alcohol 200 (positive control for drug fed mice) (Gr. IV) and fed diet and carcinogens like Gr. III, plus Natrum Sulphuiricum‐200 (Gr. V; drug fed). Mice were sacrificed at day 7, 15, 30, 60, 90 and day 120 for study of cytogenetical endpoints like chromosome aberrations (CA), micronuclei (MN), mitotic index (MI) and sperm head anomaly (SHA) and biochemical toxicity parameters like aspartate amino transferase (AST), alanine amino transferase (ALT), acid (AcP) and alkaline (AlkP) phosphatases, lipid peroxidation (LPO) and reduced glutathione (GSH) content. Less number of liver tumors were observed in Gr. V (drug fed) mice. Administration of Nat Sulph 200 reduced genomic damage, activities of AcP, AlkP, AST, ALT, LPO and increased GSH content. Therefore, independent replication of the study by others is encouraged.
CNS 7056
Authors: Kilpatrick Gavin J. , McIntyre Margaret S. , Cox Richard F. , Stafford Jeffrey A. , Pacofsky Gregory J. , Lovell Gwyer G. , Wiard Robert P. , Feldman Paul L. , Collins Holly , Waszczak Barbara L. , Tilbrook Gary S.
Published: June 2007

Background:

A new benzodiazepine derivative, CNS 7056, has been developed to permit a superior sedative profile to current agents,i.e., more predictable fast onset, short duration of sedative action, and rapid recovery profile. This goal has been achieved by rendering the compound susceptible to metabolismviaesterases. The authors now report on the profile of CNS 7056in vitroandin vivo.

Methods:

The affinity of CNS 7056 and its carboxylic acid metabolite, CNS 7054, for benzodiazepine receptors and their selectivity profiles were evaluated using radioligand binding. The activity of CNS 7056 and midazolam at subtypes (α1β2γ2, α2β2γ2, α3β2γ2, α5β2γ2) of the γ-aminobutyric acid type A (GABAA) receptor was evaluated using the whole cell patch clamp technique. The activity of CNS 7056 at brain benzodiazepine receptorsin vivowas measured in rats using extracellular electrophysiology in the substantia nigra pars reticulata. The sedative profile was measured in rodents using the loss of righting reflex test.

Results:

CNS 7056 bound to brain benzodiazepine sites with high affinity. The carboxylic acid metabolite, CNS 7054, showed around 300 times lower affinity. CNS 7056 and CNS 7054 (10 μm) showed no affinity for a range of other receptors. CNS 7056 enhanced GABA currents in cells stably transfected with subtypes of the GABAAreceptor. CNS 7056, like midazolam and other classic benzodiazepines, did not show clear selectivity between subtypes of the GABAAreceptor. CNS 7056 (intravenous) caused a dose-dependent inhibition of substantia nigra pars reticulata neuronal firing and recovery to baseline firing rates was reached rapidly. CNS 7056 (intravenous) induced loss of the righting reflex in rodents. The duration of loss of righting reflex was short (< 10 min) and was inhibited by pretreatment with flumazenil.

Conclusions:

CNS 7065 is a high-affinity and selective ligand for the benzodiazepine site on the GABAAreceptor. CNS 7056 does not show selectivity between GABAAreceptor subtypes. CNS 7056 is a potent sedative in rodents with a short duration of action. Inhibition of substantia nigra pars reticulata firing and the inhibition of the effects of CNS 7056 by flumazenil show that it acts at the brain benzodiazepine receptor.
A Double-blind, Placebo-controlled, Dose–Response Pilot Study Evaluating Intradiscal Etanercept in Patients with Chronic Discogenic Low Back Pain or Lumbosacral Radiculopathy
Authors: Cohen Steven P. , Wenzell Daniel , Hurley Robert W. , Kurihara Connie , Buckenmaier Chester C. , Griffith Scott , Larkin Thomas M. , Dahl Erik , Morlando Bennie J.
Published: June 2007

Background:

In recent years, convincing evidence has emerged implicating tumor necrosis factor α as a causative factor in radiculopathy and discogenic back pain. But although preliminary open-label studies demonstrated promising results for the treatment of low back pain with tumor necrosis factor-α inhibitors, early optimism has been tainted by a controlled study showing no significant benefit in sciatica. To determine whether outcomes might be improved by a more direct route of administration, the authors evaluated escalating doses of intradiscal etanercept in 36 patients with chronic lumbosacral radiculopathy or discogenic low back pain.

Methods:

A double-blind, placebo-controlled pilot study was conducted whereby six patients received 0.1, 0.25, 0.5, 0.75, 1.0, or 1.5 mg etanercept intradiscally in each pain-generating disc. In each escalating dose group of six patients, one received placebo. A neurologic examination and postprocedure leukocyte counts were performed in all patients at 1-month follow-up visits. In patients who experienced significant improvement in pain scores and function, follow-up visits were conducted 3 and 6 months after the procedure.

Results:

At 1-month follow-up, no differences were found for pain scores or disability scores between or within groups for any dose range or subgroup of patients. Only eight patients remained in the study after 1 month and elected to forego further treatment. No complications were reported, and no differences were noted between preprocedure and postprocedure leukocyte counts.

Conclusions:

Although no serious side effects were observed in this small study, a single low dose of intradiscal etanercept does not seem to be an effective treatment for chronic radicular or discogenic low back pain.
Endotracheal Intubation in Patients with Cervical Spine Immobilization
Authors: Maharaj Chrisen H. , Buckley Elma , Harte Brian H. , Laffey John G.
Published: June 2007

Background:

The Airtraq laryngoscope (Prodol Ltd., Vizcaya, Spain) is a novel single-use tracheal intubation device. The authors compared ease of intubation with the Airtraq and Macintosh laryngoscopes in patients with cervical spine immobilization in a randomized, controlled clinical trial.

Methods:

Forty consenting patients presenting for surgery requiring tracheal intubation were randomly assigned to undergo intubation using a Macintosh (n = 20) or Airtraq (n = 20) laryngoscope. All patients were intubated by one of four anesthesiologists experienced in the use of both laryngoscopes.

Results:

No significant differences in demographic or airway variables were observed between the groups. All but one patient, in the Macintosh group, were successfully intubated on the first attempt. The Airtraq reduced the duration of intubation attempts (mean ± SD: 13.2 ± 5.5vs.20.3 ± 12.2 s), the need for additional maneuvers, and the intubation difficulty scale score (0.1 ± 0.5vs.2.7 ± 2.5). Tracheal intubation with the Airtraq caused fewer alterations in blood pressure and heart rate.

Conclusions:

These findings demonstrate the utility of the Airtraq laryngoscope for tracheal intubation in patients with cervical spine immobilization.
Painful Nerve Injury Shortens the Intracellular Ca2+ Signal in Axotomized Sensory Neurons of Rats
Authors: Fuchs Andreas , Rigaud Marcel , Hogan Quinn H.
Published: June 2007

Background:

Neuropathic pain is inadequately treated and poorly understood at the cellular level. Because intracellular Ca2+ signaling critically regulates diverse neuronal functions, the authors examined effects of peripheral nerve injury on the Ca2+ transient that follows neuronal activation.

Methods:

Cytoplasmic Ca2+ levels were recorded by digital microfluorometry from dissociated dorsal root ganglion neurons of hyperalgesic animals after ligation of the fifth lumbar spinal nerve and control animals. Neurons were activated by field stimulation or by K+ depolarization.

Results:

Transients in presumptively nociceptive, small, capsaicin-sensitive neurons were diminished after axotomy, whereas transient amplitude increased in axotomized nonnociceptive neurons. Axotomy diminished the upward shift in resting calcium after transient recovery. In contrast, nociceptive neurons adjacent to axotomy acquired increased duration of the transient and greater baseline shift after K+ activation. Transients of nonnociceptive neurons adjacent to axotomy showed no changes after injury. In nociceptive neurons from injured rats that did not develop hyperalgesia, transient amplitude and baseline offset were large after axotomy, whereas transient duration in the adjacent neurons was shorter compared with neurons excised from hyperalgesic animals, which show normalization of these features.

Conclusions:

A diminished Ca2+ signal in axotomized neurons may be in part due to loss of Ca2+ influx through voltage-gated Ca2+ channels. The upward shift in resting Ca2+ level after activation, which is diminished after axotomy in presumed nociceptive neurons, is a previously unrecognized aspect of neuronal plasticity. These changes in the critical Ca2+ signal may mediate various injury-related abnormalities in Ca2+-dependent neuronal.
Effects of Isoflurane and Sevoflurane Anesthesia on Arteriovenous Shunt Flow in the Lower Limb of Diabetic Patients without Autonomic Neuropathy
Authors: Negoro Takaaki , Mizumoto Kazuhiro , Ogawa Koji , Hironaka Yasuo , Kakutani Tetsuya , Hatano Yoshio
Published: June 2007

Background:

Failure of sympathetic nerve control caused by diabetic neuropathy results in vasodilation of arteriovenous shunts. The aim of this study was to test the hypothesis that the function of arteriovenous anastomoses was disordered in mild diabetic patients without apparent neuropathy, and that volatile anesthetics opened arteriovenous shunts more greatly in nondiabetic patients than diabetic patients.

Methods:

Autonomic system function was assessed by cardiovascular reflex tests. Arterial–venous oxygen content difference (A-VΔO2) and partial oxygen pressure index (Pvo2/Pao2, the ratio of oxygen tension in femoral vein blood to that in femoral artery blood) were measured before and during isoflurane or sevoflurane anesthesia in 16 diabetic and 22 nondiabetic patients. Skin temperatures of the foot and leg were measured in 14 diabetic and 15 nondiabetic patients using thermography before and during anesthesia.

Results:

Pvo2/Pao2 before anesthesia was significantly higher in diabetic patients. In nondiabetics, venous oxygen content significantly increased and A-VΔO2 markedly decreased during anesthesia, but these parameters were unchanged in diabetics. Foot temperatures were higher in diabetics before anesthesia, and increased gradually and significantly in both groups during anesthesia, but with a greater increase in nondiabetic patients. Induction of anesthesia caused a larger decrease in leg temperature in diabetics than in nondiabetics.

Conclusions:

Diabetic patients have a higher Pvo2/Pao2 and a small core-to-peripheral temperature gradient before anesthesia, suggesting latent dysfunction of the autonomic nerve system, even in the absence of autonomic neuropathy. Volatile anesthesia opens the arteriovenous shunt in nondiabetics to a greater extent than in diabetic patients.
Reducing Myocardial Injury by Minimizing Imbalance between Oxygen Supply and Demand
Authors: Braunwald Eugene , Warner David S.
Published: June 2007

Factors Influencing Infarct Size following Experimental Coronary Artery Occlusion. By P. R. Maroko, J. K. Kjekshus, B. E. Sobel, T. Watanabe, J. W. Covell, J. Ross, Jr., and E. Braunwald. Circulation 1971; 43:67–82. Reprinted with permission.

The purpose of this study was to determine whether hemodynamic and pharmacologic factors can influence the extent and severity of myocardial necrosis produced by coronary occlusion. In 48 dogs, 10 to 14 epicardial leads were recorded on the anterior surface of the left ventricle in the distribution and vicinity of the site of occlusion of a branch of the left anterior descending coronary artery. The average S-T segment elevation for each animal was determined at 5-min intervals after occlusion. This elevation was used as an index of the presence and severity of myocardial ischemic injury. Isoproterenol, ouabain, glucagon, bretylium, and tachycardia given prior to a repeated occlusion each increased the severity and extent of ischemic injury, while propranolol decreased it. Elevation of arterial pressure with methoxamine reduced the occlusion-induced S-T segment elevation, and lowering of the mean arterial pressure by hemorrhage had the opposite effect. In 19 additional experiments, propranolol, isoproterenol, and alterations in arterial pressure produced similar alterations in S-T segment elevation when these interventions were applied as long as 3 hr after ligation. Myocardial creatine phosphokinase (CPK) activity determined 24 hr after coronary artery ligation correlated well with S-T segment elevation at the same sites recorded 15 min after ligation. Moreover, isoproterenol increased and propranolol decreased the area of depression of myocardial CPK activity. We conclude that the hemodynamic status and neurohumoral background at the time of coronary occlusion and for at least 3 hr thereafter can alter the extent and severity of myocardial ischemic injury and myocardial necrosis.
A functional genomics strategy reveals clockwork orange as a transcriptional regulator in the Drosophila circadian clock
Authors: Matsumoto Akira , Ukai-Tadenuma Maki , Yamada Rikuhiro G. , Houl Jerry , Uno Kenichiro D. , Kasukawa Takeya , Dauwalder Brigitte , Itoh Taichi Q. , Takahashi Kuniaki , Ueda Ryu , Hardin Paul E. , Tanimura Teiichi , Ueda Hiroki R.
Published: June 2007

The Drosophila circadian clock consists of integrated autoregulatory feedback loops, making the clock difficult to elucidate without comprehensively identifying the network components in vivo. Previous studies have adopted genome-wide screening for clock-controlled genes using high-density oligonucleotide arrays that identified hundreds of clock-controlled genes. In an attempt to identify the core clock genes among these candidates, we applied genome-wide functional screening using an RNA interference (RNAi) system in vivo. Here we report the identification of novel clock gene candidates including clockwork orange (cwo), a transcriptional repressor belonging to the basic helix–loop–helix ORANGE family. cwo is rhythmically expressed and directly regulated by CLK–CYC through canonical E-box sequences. A genome-wide search for its target genes using the Drosophila genome tiling array revealed that cwo forms its own negative feedback loop and directly suppresses the expression of other clock genes through the E-box sequence. Furthermore, this negative transcriptional feedback loop contributes to sustaining a high-amplitude circadian oscillation in vivo. Based on these results, we propose that the competition between cyclic CLK–CYC activity and the adjustable threshold imposed by CWO keeps E-box-mediated transcription within the controllable range of its activity, thereby rendering a Drosophila circadian clock capable of generating high-amplitude oscillation.
Clockwork Orange is a transcriptional repressor and a new Drosophila circadian pacemaker component
Authors: Kadener Sebastian , Stoleru Dan , McDonald Michael , Nawathean Pipat , Rosbash Michael
Published: June 2007

Many organisms use circadian clocks to keep temporal order and anticipate daily environmental changes. In Drosophila, the master clock gene Clock promotes the transcription of several key target genes. Two of these gene products, PER and TIM, repress CLK–CYC-mediated transcription. To recognize additional direct CLK target genes, we designed a genome-wide approach and identified clockwork orange (cwo) as a new core clock component. cwo encodes a transcriptional repressor that synergizes with PER and inhibits CLK-mediated activation. Consistent with this function, the mRNA profiles of CLK direct target genes in cwo mutant flies manifest high trough values and low amplitude oscillations. Because behavioral rhythmicity fails to persist in constant darkness (DD) with little or no effect on average mRNA levels in flies lacking cwo, transcriptional oscillation amplitude appears to be linked to rhythmicity. Moreover, the mutant flies are long period, consistent with the late repression indicated by the RNA profiles. These findings suggest that CWO acts preferentially in the late night to help terminate CLK–CYC-mediated transcription of direct target genes including cwo itself. The presence of mammalian homologs with circadian expression features (Dec1 and Dec2) suggests that a similar feedback mechanism exists in mammalian clocks.
The Flask model: emergence of nutrient‐recycling microbial ecosystems and their disruption by environment‐altering ‘rebel’ organisms
Authors: Williams Hywel T. P. , Lenton Timothy M.
Published: June 2007

Here we introduce a new model of life–environment interaction, which simulates an evolving microbial community in a ‘Fask’ of liquid with prescribed inputs of nutrients. The flask is seeded with a clonal population of ‘microbes’ that are subject to mutation on genetic loci that determine their nutrient uptake patterns, release patterns, and their effects on, and response to, other environmental variables. In contrast to existing models of life‐environment interaction, notably Daisyworld, what benefits the individual organisms is decoupled from their ‘global’ (system‐level) effects. A robust property of the model is the emergence of ecosystems that tend toward a state where nutrients are efficiently utilised and differentially recycled, with a correlated increase in total population. Organisms alter the environment as a free ‘by‐product’ of their growth, and their growth is constrained by adverse environmental effects. This introduces environmental feedback, which can disrupt the model ecosystems, even though there are no constraints on the conditions to which the organisms can theoretically adapt. ‘Rebel’ organisms can appear that grow rapidly by exploiting an under‐utilised resource, but in doing so shift the environment away from the state to which the majority of the community are adapted. The result can be a population crash with lossof recycling, followed by later recovery, or in extreme cases, a total extinction of the system. Numerous runs of these ‘flask’ ecosystems show that tighter environmental constraints on growth make the system more vulnerable to internally generated ecosystem extinction.
WOULD YOU LIKE TO ENTER FIRST WITH A LOW‐QUALITY GOOD?
Authors: Lambertini Luca , Tedeschi Piero
Published: June 2007

Using a two‐period duopoly model with vertical differentiation, we show that there exists a unique subgame perfect equilibrium where the first entrant supplies a lower quality and gains higher profits than the second entrant. We also prove that this entry sequence is socially efficient.
Influence of egg predation and physical disturbance on lake trout Salvelinus namaycush egg mortality and implications for life‐history theory
Authors: Fitzsimons J. D. , Jonas J. L. , Claramunt R. M. , Williston B. , Williston G. , Marsden J. E. , Ellrott B. J. , Honeyfield D. C.
Published: June 2007

The influence of egg predators and physical disturbance on lake trout Salvelinus namaycush egg mortality was investigated in situ in Lake Michigan where recruitment is below detectable levels and egg predator abundance is high. Comparisons were made with Lake Champlain where recruitment is low and egg predator abundance is also low and with Parry Sound (Lake Huron) where recruitment is moderate and egg predators are in low abundance. A multi‐density egg seeding method (100 to 5000 eggs m−2) was used to quantify the effect of physical disturbance and egg predation on egg loss. Wind fetch was used as an index of physical disturbance and comparisons across all locations and egg densities suggested that at sites with high wind fetch (>5 km), physical disturbance may be a greater source of egg loss than predation. When analyses were limited to those sites having a wind fetch of <5 km, the percentage of eggs recovered was found to be linearly related to predator density. The strength of this relationship was based largely on egg recovery at 500 and 1000 eggs m−2 because recovery at lower (100, 250 eggs m−2) and very high (5000 eggs m−2) densities was not significantly related to predator density. The reason for this is probably that at low egg densities, crayfish Orconectes spp., the major egg predator at most sites, had difficulty finding and consuming eggs and at high egg densities they became satiated. Egg loss was directly related to wind fetch for Lake Michigan and on average six‐fold greater than for Parry Sound suggesting that without corresponding changes in fecundity and age structure, lake trout populations in large lakes like Lake Michigan are inherently less productive than those from enclosed inland waters.
Starvation and low feeding levels result in an enrichment of 13C in lipids and 15N in protein of Nile tilapia Oreochromis niloticus L.
Authors: Gaye‐Siessegger J. , Focken U. , Abel Hj , Becker K.
Published: June 2007

The influence of different feeding levels below and slightly above maintenance on whole body δ13C and δ15N values of Nile tilapia Oreochromis niloticus was examined. The energy budget of each fish was determined by indirect calorimetry. The δ13C values of the lipid‐free material of Nile tilapia fed below and slightly above maintenance level did not differ between the feeding groups, but the δ13C values in the lipids and the δ15N values of the lipid‐free material showed small but significant differences. Those fish with a negative lipid retention had significantly higher δ13C values in the lipid fraction compared to fish that synthesized fatty acids. There was a significant negative correlation between the amount of energy metabolized by the fish and both the δ13C values in the lipids and the δ15N values of the lipid‐free material. Fasting and feeding below the maintenance level may influence the isotopic composition of animals and should therefore be considered in ecological and nutritional studies.
Evidence for an autumn downstream migration and the subsequent estuarine residence of 0+ year juvenile Atlantic salmon Salmo salar L., in England
Authors: Pinder A. C. , Riley W. D. , Ibbotson A. T. , Beaumont W. R. C.
Published: June 2007

The use of passive integrated transponder technology facilitated the first observations of the autumn migration of 0+ year Atlantic salmon Salmo salar parr into tidal rearing habitats in the U.K. The quality of these habitats in relation to smolt production and the ecological significance of this alternative life‐history strategy are presently not understood.
Diurnal and seasonal behaviour of adult and juvenile European catfish as determined by radio‐telemetry in the River Berounka, Czech Republic
Authors: Slavík O. , Horký P. , Bartoš L. , Kolářová J. , Randák T.
Published: June 2007

The first telemetry study analysing behaviour of the largest freshwater predator in European rivers, Silurus glanis, was performed bimonthly during the years 2002–2004. Movement of juveniles and adults occurred mostly in the same time intervals. The only statistical differences occurred for nocturnal activity in spring and autumn. In spring and winter, activity was low with the peaks during daylight, and in autumn, maximal movement was recorded during dusk. In summer, the European catfish were active across the whole 24 h even during high‐flow conditions. During all other seasons, movement was inversely related to flow rate. Maximal home ranges occurred in summer, being larger for adults. Juveniles and adults were spatially segregated. With increasing flow, fish were displaced, and individuals from both groups got closer to each other. Only juveniles migrated downstream from the upstream isolated river stretch suggesting a negative impact of lateral obstructions on the fish population structure.