bluuebunny/crossref_metadata_2025 huggingface dataset:
In vitro interaction of human fibroblasts and platelets with a shape‐memory polyurethane
Authors: Farè Silvia , Valtulina Viviana , Petrini Paola , Alessandrini Edoardo , Pietrocola Giampiero , Tanzi M. Cristina , Speziale Pietro , Visai Livia
Published: February 2005

Physicochemical and mechanical properties, in vitro cytotoxicity, cytocompatibility, and platelet adhesion were investigated on a shape‐memory polyether‐based polyurethane (MM‐5520 SMPu) using the polyether‐based Pellethane 2363‐80AE (Pell‐2363 SPU) as reference. MM‐5520 SMPu and Pell‐2363 SPU showed similar average molecular weights and different surface properties, with a higher hydrophilicity and roughness for the SMPu. By tensile tests and dynamic mechanical analysis, the peculiar characteristics of the MM‐5520 SMPu were evidenced: strong temperature‐dependent behavior for SMPu compared with SPU, and a high shape recovery. MM‐5520 SMPu did not show any cytotoxic effect on the adhesion and proliferation of human skin fibroblasts and gingival fibroblasts, and a good cytocompatibility was observed with both cell types, as demonstrated by cell counting and scanning electron microscopy observations. SMPu compared with SPU showed higher adsorption of extracellular matrix proteins such as fibronectin, fibrinogen, and collagens. Proteins adsorbed onto SMPu significantly enhanced the adhesion and proliferation of human fibroblasts. The interaction of SMPu with platelets was studied with platelet rich plasma. Fewer platelets adhered to the SMPu, with minor morphological variations than onto the SPU. The cytocompatibility and hemocompatibility of MM‐5520 SMPu combined with its unique properties such as change in shape or in stiffness, depending on practical requirements, make this shape‐memory material potentially advantageous for biomedical applications. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res 73A: 1–11, 2005
Osteoblast response to thermally oxidized Ti6Al4V alloy
Authors: Saldaña L. , Vilaboa N. , Vallés G. , González‐Cabrero J. , Munuera L.
Published: February 2005

We have recently reported that thermal oxidation treatments of Ti6Al4V at 500° and 700°C for 1 h result in the formation of an outer “ceramic” layer of rutile that do not decrease the high in vitro corrosion resistance of the alloy. In the present work, surface roughness was measured and found marginally increased as a consequence of oxidation of the alloy at 700°C, but not at 500°C. We have evaluated the biocompatibility of the oxidized surfaces, by assessing cell adhesion, proliferation, and differentiation of primary cultures of human osteoblastic cells. Compared with polished alloy, both thermal treatments increased osteoblast adhesion measured as cell attachment, β1 integrin and FAK‐Y397 expression, as well as cytoskeletal reorganization. Compared with treatment at 500°C, thermal oxidation at 700°C enhanced cell adhesion. Treatment at 700°C transiently impaired cell proliferation and viability, which were not altered in alloys oxidized at 500°C. Several markers of osteoblastic differentiation such as procollagen I peptide, alkaline phosphatase, osteocalcin, and mineralized nodule formation were found either unaffected or differentially increased by alloys treated either at 500° or 700°C. In addition, thermal oxidation at 700°C also increased osteoprotegerin secretion. Taken together, our results indicate that thermal oxidation treatments at 500° or 700°C for 1 h improve the in vitro biocompatibility of Ti6Al4V. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res 73A: 97–107, 2005
Assessment of the cytocompatibility of different coated titanium surfaces to fibroblasts and osteoblasts
Authors: Harris Llinos G. , Patterson Louisa M. , Bacon Claire , Gwynn Iolo ap , Richards R. Geoff
Published: February 2005

Over the years, many metal and polymer implants have been developed for internal fracture fixation. However, there are always some problems associated with their application, such as implant loosening or infection. This study describes how the morphology and adhesion of both fibroblasts and osteoblasts to two manufactured commercially pure, medical implant‐quality anodized titanium surfaces (TS and TSS), and five modified titanium surfaces (TLF, low friction gray anodized titanium; TIG, nitrogen ion implanted TSS; THY, TSS grafted with sodium hyaluronate; TAST, TSS coated with hydrophilic hydrogel; and TT, tiodized TS) were used to obtain an indication of their relative cytocompatibility and to assess which modified surface could potentially be used in vivo. Small variations were observed both qualitatively and quantitatively in the spreading and adhesion of fibroblasts and osteoblasts to the studied surfaces. Overall, fibroblast spreading and adhesion were greatest on the TIG and TLF surfaces. Osteoblast spreading and adhesion were greatest on TS, TIG, and TAST surfaces. No fibroblasts or osteoblasts were found attached to the THY‐coated surfaces. Coating medical implant‐quality anodized titanium surfaces (TS and TSS) with a TLF, TAST, or more specifically TIG could probably improve soft tissue adhesion and/or osseointegration of bone in vivo. However, it seemed that a hyaluronic acid coating (THY) has potential as a coating in areas where cell adhesion is undesirable, such as orbital fractures, where muscles should avoid adhesion to the implant, and distal radius fractures, where tendons should freely glide over the implant. © 2005 Wiley Periodicals, Inc. J Biomed Mater Res 73A: 12–20, 2005
XMVB: A program for ab initio nonorthogonal valence bond computations
Authors: Song Lingchun , Mo Yirong , Zhang Qianer , Wu Wei
Published: February 2005

An ab initio nonorthogonal valence bond program, called XMVB, is described in this article. The XMVB package uses Heitler–London–Slater–Pauling (HLSP) functions as state functions, and calculations can be performed with either all independent state functions for a molecule or preferably a few selected important state functions. Both our proposed paired‐permanent–determinant approach and conventional Slater determinant expansion algorithm are implemented for the evaluation of the Hamiltonian and overlap matrix elements among VB functions. XMVB contains the capabilities of valence bond self‐consistent field (VBSCF), breathing orbital valence bond (BOVB), and valence bond configuration interaction (VBCI) computations. The VB orbitals, used to construct VB functions, can be defined flexibly in the calculations depending on particular applications and focused problems, and they may be strictly localized, delocalized, or bonded‐distorted (semidelocalized). The parallel version of XMVB based on MPI (Message Passing Interface) is also available. © 2005 Wiley Periodicals, Inc. J Comput Chem 26: 514–521, 2005
Skin model surface temperatures during single and multiple cryogen spurts used in laser dermatologic surgery
Authors: Ramirez‐San‐Juan Julio C. , Aguilar Guillermo , Tuqan Alia T. , Kelly Kristen M. , Nelson J. Stuart
Published: February 2005

Background

Although cryogen spray cooling (CSC) is used to minimize the risk of epidermal damage during laser dermatologic surgery, concern has been expressed that CSC may induce cryo‐injury. In order to address this concern, it is necessary to evaluate the effects of prolonged exposure of human skin phantoms (HSP) to CSC.

Objective

To measure the minimum surface temperature (Tmin) and the time at which it occurs (tTmin) as well as determine the time the sprayed HSP surface remains below 0°C (sub‐zero time, Δts) and −26°C (residence time, Δtr) during the application of single (SCS) and multiple (MCS) cryogen spurts. Two initial HSP substrate temperatures were studied, Ti: 23 and 70°C.

Study Design/Materials and Methods

An epoxy‐based HSP was constructed to measure Tmin, tTmin, Δts, and Δtr, for 17 spray patterns: 1 SCS with a total cryo‐delivery time (Δtc) of 40 milliseconds; 8 MCS patterns with identical Δtc, but with a total cooling time (Δttotal) varying from 50 to 280 milliseconds; and 8 SCS patterns that matched the Δttotal of the MCS patterns.

Results

For both Ti, our results show that it is possible to distinguish between two different cooling regimes. For Δttotal ≤ 110 milliseconds, the differences between SCS and MCS patterns with the same Δttotal for all variables (Tmin, tTmin, Δts, Δtr) are negligible. Most importantly, all these variables show a remarkable linear dependence with Δttotal. In the interval 110 milliseconds < Δttotal < 280 milliseconds, Tmin and tTmin are similar for SCS and MCS, while Δts and Δtr show more pronounced differences between the two spray patterns. In this interval, the values of Tmin and Δts for MCS remain invariant and similar to the corresponding values for Δttotal = 110 milliseconds.

Conclusions

These results suggest that: (1) similar epidermal protection may be attained with SCS and MCS for Δttotal ≤ 110 milliseconds; and (2) for 110 milliseconds < Δttotal ≤ 280 milliseconds, MCS help to maintain Δts similar to that of SCS at Δttotal = 100 milliseconds, which may be beneficial to prevent cryo‐injury. Lasers Surg. Med. 36:141–146, 2005. © 2005 Wiley‐Liss, Inc.
A fast multi‐level convolution boundary element method for transient diffusion problems
Authors: Wang C.‐H. , Grigoriev M. M. , Dargush G. F.
Published: February 2005

A new algorithm is developed to evaluate the time convolution integrals that are associated with boundary element methods (BEM) for transient diffusion. This approach, which is based upon the multi‐level multi‐integration concepts of Brandt and Lubrecht, provides a fast, accurate and memory efficient time domain method for this entire class of problems. Conventional BEM approaches result in operation counts of order O(N2) for the discrete time convolution over N time steps. Here we focus on the formulation for linear problems of transient heat diffusion and demonstrate reduced computational complexity to order O(N3/2) for three two‐dimensional model problems using the multi‐level convolution BEM. Memory requirements are also significantly reduced, while maintaining the same level of accuracy as the conventional time domain BEM approach. Copyright © 2005 John Wiley & Sons, Ltd.
Discrete material optimization of general composite shell structures
Authors: Stegmann J. , Lund E.
Published: February 2005

A novel method for doing material optimization of general composite laminate shell structures is presented and its capabilities are illustrated with three examples. The method is labelled Discrete Material Optimization (DMO) but uses gradient information combined with mathematical programming to solve a discrete optimization problem. The method can be used to solve the orientation problem of orthotropic materials and the material selection problem as well as problems involving both. The method relies on ideas from multiphase topology optimization to achieve a parametrization which is very general and reduces the risk of obtaining a local optimum solution for the tested configurations. The applicability of the DMO method is demonstrated for fibre angle optimization of a cantilever beam and combined fibre angle and material selection optimization of a four‐point beam bending problem and a doubly curved laminated shell. Copyright © 2005 John Wiley & Sons, Ltd.
Targeted therapy: For kids, too
Authors: Corey Seth J.
Published: February 2005

Innovative hypothesis‐driven clinical trials have achieved major successes over the past several decades in treating children and adolescents with cancer. DNA‐damaging cytotoxic agents have cured children with cancer. While the mission is not yet accomplished, chemotherapy has been validated. None of these drugs were designed specifically for a pediatric disease. Continued progress will require new strategies. Now being tested for adult cancers, these strategies include gene therapy, immunotherapy, cancer prevention, and signal transduction inhibitor (STI) therapy. Of these, the most promising is STI therapy, also known as molecular therapeutics or targeted therapy. For this therapy to succeed, components of signal transduction (i.e., candidate drug targets) must be identified, the targets relevant to cancers, and the drugs available for trial. Because STI therapy is biologically driven and because therapy will be tailored depending on the molecular profile of a specific patient's tumor, clinical pediatric oncologists will need to acquire greater understanding of signaling pathways and their therapeutic relevance. With examples drawn from pediatric oncology, the critical steps in the pre‐clinical development of targeted therapy are reviewed here. © 2005 Wiley‐Liss, Inc.
Safety and tolerability of denufosol tetrasodium inhalation solution, a novel P2Y2 receptor agonist: Results of a phase 1/phase 2 multicenter study in mild to moderate cystic fibrosis
Authors: Deterding Robin , Retsch‐Bogart George , Milgram Laura , Gibson Ron , Daines Cori , Zeitlin Pamela L. , Milla Carlos , Marshall Bruce , LaVange Lisa , Engels Jean , Mathews Dave , Gorden JoAnn , Schaberg Amy , Williams Judy , Ramsey Bonnie ,   for the Cystic Fibrosis Foundation Therapeutics Development Network
Published: February 2005

Denufosol tetrasodium (INS37217) is a selective P2Y2 agonist that stimulates ciliary beat frequency and Cl− secretion in normal and cystic fibrosis (CF) airway epithelia, and is being investigated as an inhaled treatment for CF. The Cl− secretory response is mediated via a non‐CFTR pathway, and the driving force for Cl− secretion is enhanced by the effect of P2Y2 activation to also inhibit epithelial Na+ transport. Denufosol is metabolically more stable and better tolerated, and may enhance mucociliary clearance for a longer period of time than previously investigated P2Y2 agonists. The goal of this phase 1/phase 2 study was to assess the safety and tolerability of single and repeated doses of aerosolized denufosol in subjects with CF. The study was a double‐blind, placebo‐controlled, multicenter comparison of ascending single doses of denufosol (10, 20, 40, and 60 mg, administered by inhalation via the Pari LC Star® nebulizer) vs. placebo (normal saline), followed by a comparison of twice‐daily administration of the maximum tolerated dose (MTD) of denufosol or placebo for 5 days. Thirty‐seven adult (18 years of age or older) and 24 pediatric (5–17 years of age) subjects with CF were evaluated in five cohorts. Subjects were randomized in a 3:1 ratio to receive either denufosol or placebo within each cohort. The percent of subjects experiencing adverse events was similar between the denufosol and placebo groups. The most common adverse event in subjects receiving denufosol was chest tightness in adult subjects (39%) and cough in pediatric subjects (56%). Three (7%) subjects receiving denufosol and one (7%) subject receiving placebo experienced a serious adverse event. Forced expiratory volume in 1 sec (FEV1) profiles following dosing were similar across treatment groups, with some acute, reversible decline seen in both groups, most notably in subjects with lower lung function at baseline. In conclusion, doses up to 60 mg of denufosol inhalation solution were well‐tolerated in most subjects. Some intolerability was noted among subjects with lower baseline lung function. Based on the results of this phase 1/phase 2 study, the Therapeutics Development Network (TDN) of the Cystic Fibrosis Foundation (CFF) and Inspire Pharmaceuticals, Inc., recently completed a multicenter, 28‐day, phase 2 safety and efficacy clinical trial of denufosol inhalation solution in CF subjects with mild lung disease. Pediatr Pulmonol. 2005; 39:339–348. © 2005 Wiley‐Liss, Inc.
Sleep and breathing on the first night after adenotonsillectomy for obstructive sleep apnea
Authors: Nixon G.M. , Kermack A.S. , McGregor C.D. , Davis G.M. , Manoukian J.J. , Brown K.A. , Brouillette R.T.
Published: February 2005

Adenotonsillectomy (T&A) has established effectiveness for the treatment of obstructive sleep apnea (OSA). However, more than 20% of children with OSA have respiratory compromise requiring medical intervention in the postoperative period. The reasons for this complication are not well‐defined. We aimed to compare the nature and severity of sleep‐disordered breathing in children with mild and severe OSA on the first night following adenotonsillectomy. Ten children were classified into groups of mild and severe OSA, based on preoperative testing. On the first night after T&A, they underwent polysomnography, including electroencephalograph, submental electromyography, bilateral electro‐oculograms, monitoring of respiratory movements, heart rate, ECG, and oxygen saturation. Sleep‐disordered breathing was assessed by the apnea‐hypopnea index, the SaO2 nadir, and the desaturation index, including dips in saturation below 90% (DI90). Sleep quality was assessed by sleep efficiency, time spent in each sleep state, and respiratory arousal index. Obstructive events occurred postoperatively in all children, but were more frequent in those with severe OSA preoperatively: the median (interquartile range) mixed/obstructive apnea/hypopnea indicies were 6.9 (2.2–9.8) events/hr and 21.5 (15.1–112.1) events/hr for the mild OSA group and the severe OSA group, respectively (P = 0.009). Obstructive events were the major cause of desaturation during sleep postoperatively. Sleep quality was severely disrupted in both groups, with reductions in both slow‐wave sleep and rapid eye movement sleep. In conclusion, despite removal of obstructing lymphoid tissue, upper airway obstruction occurred on the first postoperative night in children with OSA. This study is the first to demonstrate the mechanism of respiratory compromise after adenotonsillectomy, a common postoperative complication in children with severe OSA. Pediatr Pulmonol. 2005; 39:332–338. © 2005 Wiley‐Liss, Inc.
Underestimation of the peak flow variability in asthmatic children: Evaluation of a new formula
Authors: Vargas Mario H. , Ruiz‐Gutiérrez Héctor Hernán , Espinosa‐Serafin Concepción , Zúñiga‐Vázquez Guillermo , Furuya María E.Y.
Published: February 2005

Asthma guidelines suggest evaluation of peak expiratory flow (PEF) variability, but timing for the two PEF measurements is not mentioned. Usual formula calculates amplitude as percentage of mean day‐night PEF values. Since PEF circadian changes follow a sinusoidal function, we reasoned that variability might be calculated by measuring PEF at 4 pm (PEF1) and either at 10 am or 10 pm (PEF2) with the formula %variability = 200 · |PEF1‐PEF2|/PEF2. Children with stable, mild intermittent asthma were recruited from an Asthma Clinic and asked to perform PEF measurements at even hours during a week, until 12 measurements covering a 24‐h period were accomplished. From these measurements we calculated PEF variability through several methods. Accuracy of such methods to predict actual PEF variability was assessed through the concordance correlation coefficient (rc). Thirty five asthmatic children were recruited. Actual PEF variability, calculated with the usual formula using the highest and lowest PEF obtained at any time of the 24 h cycle had a median of 37.3% (range, 0–88.5%). Variability calculated through other methods was: usual formula with highest and lowest PEF obtained from the sinusoidal curve, 21.4% (rc = 0.79); usual formula with PEF measured at 4 pm and 4 am, 17.8% (rc = 0.67); proposed formula using PEF measured at 4 pm and either 10 pm, 15.9% (rc = 0.68), or 10 am, 17.4% (rc = 0.69). Some examples with PEF measured in the morning (8 am or 10 am) and at night (8 pm or 10 pm) yielded median PEF variability from 4.0% (rc = 0.18) to 8.7% (rc = 0.38). Current methods for calculating PEF variability seemed not to be accurate enough as to be confident, suggesting that an in‐deep reevaluation of the usefulness of PEF variability or, conversely, of the methods to assess it, should be done. Pediatr Pulmonol. 2005; 39:325–331. © 2005 Wiley‐Liss, Inc.
Accuracy of a 12‐lead electrocardiogram in screening patients with suspected heart failure for open access echocardiography: a systematic review and meta‐analysis
Authors: Khunti K. , Squire I. , Abrams K.R. , Sutton A.J.
Published: February 2005

Aim:

The aim of this study was to examine the usefulness of 12‐lead electrocardiogram in screening patients with suspected heart failure for open access echocardiography. We carried out a systematic review and meta‐analysis of published observational studies. Published studies were identified in the Medline and Embase databases, this was supplemented by key texts, personal reference collections and examining the cited references in the above sources. English language articles in which patients were referred from primary care with a presumptive diagnosis of heart failure to an open access echocardiography service were reviewed. We included studies that reported both electrocardiography findings and echocardiography as a reference standard. Primary outcome measures were sensitivity and specificity, metaanalysed simultaneously to produce a Summary Receiver Operating Characteristic (SROC) curve.

Results:

Four trials were identified which satisfied the inclusion criteria, including 1419 people with a potential diagnosis of heart failure referred for open access echocardiography. Estimates of sensitivity and specificity varied greatly in individual studies. The area under the SROC curve was 0.84 (95% CI: 0.33 to 1.00).

Conclusion:

A 12‐lead electrocardiogram is an inadequate screening tool for identifying patients with suspected heart failure who require echocardiography. Further research is required to determine the usefulness of other screening strategies including B‐type natriuretic peptide in screening patients with suspected heart failure who need referral for open access echocardiography.
Clinical trials update from the European Society of Cardiology Heart Failure meeting: SHAPE, BRING‐UP 2 VAS, COLA II, FOSIDIAL, BETACAR, CASINO and meta‐analysis of cardiac resynchronisation therapy
Authors: Coletta Alison P. , Cleland John G.F. , Freemantle Nick , Clark Andrew L.
Published: February 2005

This article continues a series of reports on recent research developments in the field of heart failure. Key presentations made at the European Society of Cardiology Heart Failure Update meeting, held in Wroclaw, Poland, in June 2004 are reported. The SHAPE study identified a need to educate general practitioners (GPs) in order to optimise treatment of heart failure in primary care. BRING‐UP 2 VAS showed that cognitive impairment is very common in elderly heart failure patients and that these patients require specialist care. Carvedilol was shown to be well tolerated and effective in elderly heart failure patients in the observational COLA II study. In the FOSIDIAL study of patients with end‐stage renal disease, fosinopril showed no benefit over placebo in reducing the incidence of cardiovascular events in these high‐risk patients. The BETACAR study showed that carvedilol and metoprolol produced a similar effect on left ventricular ejection fraction (+13.1% and +12.0%, respectively). Revised mortality data for the CASINO study and a meta‐analysis of the effects of cardiac resynchronisation therapy on mortality in the light of the recently published COMPANION study are reported.
Reflection seismic profiles of the core‐mantle boundary
Authors: Ross A. R. , Thybo H. , Solidilov L. N.
Published: February 2005

High amplitude, high frequency, and laterally coherent seismic phases from the core‐mantle boundary (CMB) are observed on data from Peaceful Nuclear Explosions in Siberia. These arrivals are observed at 2600–4000 km offset with travel times and move‐outs consistent with CMB reflections (PcP) and are readily correlated because of the small station interval of 10 km. The duration and complexity of the arrivals are inconsistent with a simple reflection from a single CMB interface. They require the combination of PcP and a complex precursor phase (PdP) from the top of an ultralow‐velocity zone (ULVZ) despite the fact that earthquake recordings indicate that there is no ULVZ present beneath this part of Siberia. Lateral variations in the waveform imply that the thickness and physical properties of the ULVZ change with a wavelength of 150–200 km and an amplitude of up to 8 km. We find at least one location where there is no ULVZ present. At another well‐sampled location, the precursor has higher frequency content than the primary arrival. Reflectivity modeling of these PcP/PdP phases shows that kilometer‐scale layering may be required in the ULVZ to explain the seismic waveform and the frequency split. The modeling shows very low velocity in the ULVZ with reductions of 25 and 40% for P and S waves, respectively. This indicates higher percentages of partial melt in the ULVZ than hitherto interpreted. Our observations indicate that the ULVZ may be present over wide areas of the Earth with a thickness below the resolution limit of seismological data with a lower frequency content.
Imaging seismic velocity structure beneath the Iceland hot spot: A finite frequency approach
Authors: Hung Shu‐Huei , Shen Yang , Chiao Ling‐Yun
Published: February 2005

Tomographic models based on hypothetically infinite frequency ray interpretation of teleseismic travel time shifts have revealed a region of relatively low P and S wave speeds extending from shallow mantle to 400 km depth beneath Iceland. In reality, seismic waves have finite frequency bandwidths and undergo diffractive wave front healing. The limitation in ray theory leaves large uncertainties in the determinations of the magnitude and shape of the velocity anomaly beneath Iceland and its geodynamic implications. We developed a tomographic method that utilizes the banana‐shaped sensitivity of finite frequency relative travel times from the paraxial kernel theory. Using available seismic data from the ICEMELT and HOTSPOT experiments, we applied the new method to image subsurface velocity structure beneath Iceland. Taking advantage that the sensitivity volume of broadband waveforms varies with frequency, we measured relative delay times in three frequency ranges from 0.03 to 2 Hz for P and 0.02 to 0.5 Hz for S waves. Given similar fit to data, the kernel‐based models yield the root‐mean‐square amplitudes of P and S wave speed perturbations about 2–2.8 times those from ray tomography in the depths of 150–400 km. The kernel‐based images show that a columnar low‐velocity region having a lateral dimension of ∼250–300 km extends to the base of the upper mantle beneath central Iceland, deeper than that resolved by the ray‐based studies. The improved resolution in the upper mantle transition zone is attributed to the deeper crossing of broad off‐path sensitivity of travel time kernels than in ray approximation and frequency‐dependent wave front healing as an intrinsic measure of the distance from velocity heterogeneity to receivers.
Attenuation of spectral actinic flux and photolysis frequencies at the surface through homogenous cloud fields
Authors: Monks Paul S. , Rickard Andrew R. , Hall Stacey L. , Richards Nigel A. D.
Published: February 2005

The effect of clouds on derived photolysis rates has been investigated using actinic flux spectra measured from a 2π sr diode‐array spectral radiometer deployed in a series of differing field campaigns. Homogenously cloudy and clear days were selected, and ratios of cloudy‐to‐clear actinic flux spectra were used to derive a cloud transmittance slope (CTS), which is calculated as the gradient of the cloudy/clear ratio plot at 340 < λ < 420 nm. CTS is a measure of the wavelength dependence of actinic flux attenuation by clouds and shows an approximately linear dependence with solar zenith angle. When the solar zenith angle is high, the CTS is largest because of the enhanced path length of radiation through the scattering medium. The dependence of measured CTS under a range of atmospheric conditions is explored; the slopes of the CT being rationalized in terms of the cloud optical depth and single scattering albedo of the cloud. The appearance of a short‐wave enhancement in CT in a multiple scattering environment is noted in agreement with theory. The photolysis frequency coefficients j(O1D) and j(NO2), calculated from the measured actinic fluxes, are compared to observe the effect of wavelength‐dependent attenuation of actinic flux on photochemical reactions. After the subtraction of the effect of changing overhead ozone column, the effect of cloud was quite variable in that j(NO2) was found to be reduced to a greater extent than j(O1D) by some clouds or vice versa depending on the individual case. The results clearly demonstrate that photolysis frequencies in the UVB and UVA do not vary linearly under different atmospheric conditions in a cloudy field.
Study and design of a broadband coplanar waveguide–fed modified folded slot antenna
Authors: Ali M. , Usaha R. , Hu Y.
Published: February 2005

This paper presents the study and design of a coplanar waveguide–fed broadband modified folded slot antenna, including new techniques to achieve broad impedance bandwidth when the antenna size is small. Antenna impedance and bandwidth are investigated as functions of slot parameters, substrate dielectric constant, and substrate thickness. Prototypes of broadband antennas are fabricated on RO4003 (ɛr = 3.38) and are measured. Two types of antennas are proposed with respective bandwidths of 44.4 and 80% with less than 2:1 VSWR.
Chemical composition of Titan's haze: Are PAHs present?
Authors: Trainer Melissa G. , Pavlov Alexander A. , Jimenez Jose L. , McKay Christopher P. , Worsnop Douglas R. , Toon Owen B. , Tolbert Margaret A.
Published: February 2005

Previous laboratory studies of haze aerosols analogous to those in Titan's atmosphere have shown evidence of the formation of polycyclic aromatic hydrocarbons (PAHs). If present, PAHs may provide a mechanism for both particle formation and nitrogen incorporation. We have conducted new experiments simulating Titan haze production using an Aerosol Mass Spectrometer (AMS). The AMS allows us to examine the chemical structure of the haze particles under a variety of starting conditions in real‐time and without collection. Our results for particles produced from a mixture of 10% CH4 in N2 are consistent with a large fraction of aromatics, including specific m/z peaks likely due to PAHs. However, at lower concentrations of CH4 (1% and lower), the mass fraction of PAHs greatly diminishes, and an aliphatic pathway dominates. Haze containing sediments may trace the history of methane on Titan through their composition. The implications for Titan haze and for observations from the Huygens probe are discussed.
A major Holocene ENSO anomaly during the Medieval period
Authors: Rein Bert , Lückge Andreas , Sirocko Frank
Published: February 2005

Here, we present a high resolution marine El Niño flood record from Peru. A period of extreme drought without strong flooding occurred from A.D. 800–1250. Anomalous precipitation patterns characterized the entire Indo‐Pacific ENSO domain, with dry events in the northern Arabian Sea and the mid‐latitudes of both Americas, coinciding with wet periods in the Atlantic Cariaco Basin. The occurrence of contemporaneous moisture anomalies in other archives in the ENSO region highlights the role of El Niño strength in global climate evolution during the late Medieval period when temperature reconstructions show a rather heterogeneous pattern.
Possible ENSO signals prior to the Last Glacial Maximum, during the last deglaciation and the early Holocene, from New Zealand
Authors: Pepper A. C. , Shulmeister J. , Nobes D. C. , Augustinus P. A.
Published: February 2005

Annually laminated lake sediments from a maar crater in Auckland, New Zealand, were analyzed spectrally for three time slices: just prior to the last glacial maximum (LGM), during the deglaciation and during the early Holocene. Strong spectral power in 2–7 year, 9–30 year and a centennial (80–120 year) timescale prior to the LGM and during two brief intervals in the deglaciation contrasts with virtually no spectral power during the rest of the deglaciation and during the early Holocene. The Antarctic Cold Reversal (ACR) appears to be the younger deglacial event. The results indicate that El Niño Southern Oscillation (ENSO) and possibly the Inter‐decadal Pacific Oscillation (IPO), operated in a modern mode prior to the LGM, pulsed on and off during the deglaciation and were suppressed or absent from northern New Zealand during the early Holocene. The ACR was a period of enhanced south‐westerly flow over northern New Zealand.
A simple approach to the joint inversion of seismic body and surface waves applied to the southwest U.S.
Authors: West Michael , Gao Wei , Grand Stephen
Published: February 2005

Body and surface wave tomography have complementary strengths when applied to regional‐scale studies of the upper mantle. We present a straight‐forward technique for their joint inversion which hinges on treating surface waves as horizontally‐propagating rays with deep sensitivity kernels. This formulation allows surface wave phase or group measurements to be integrated directly into existing body wave tomography inversions with modest effort. We apply the joint inversion to a synthetic case and to data from the RISTRA project in the southwest U.S. The data variance reductions demonstrate that the joint inversion produces a better fit to the combined dataset, not merely a compromise. For large arrays, this method offers an improvement over augmenting body wave tomography with a one‐dimensional model. The joint inversion combines the absolute velocity of a surface wave model with the high resolution afforded by body waves—both qualities that are required to understand regional‐scale mantle phenomena.
Comparison of two approaches for downscaling synoptic atmospheric patterns to multisite precipitation occurrence
Authors: Mehrotra R. , Sharma Ashish , Cordery Ian
Published: February 2005

The physical linkages between climate on the large scale and weather on the local scale allow the formulation of downscaling approaches for assessing the impact of climate variability at point locations. This paper presents a comparison between two such approaches applied for downscaling synoptic atmospheric patterns to point rainfall occurrences on a rain gauge network. The approaches evaluated are the parametric nonhomogenous hidden Markov model (NHMM) and the nonparametrick‐nearest neighbor downscaling approach. The NHMM defines local‐scale weather as a function of a discrete weather state that is Markovian and depends on predictor variables representing synoptic atmospheric patterns. As the model is defined parametrically, the number of parameters that need specification increases as one considers more discrete weather states. Consequently, parameter identification and generalization to ungauged sites becomes difficult. On the other hand, nonparametric resampling is attractive because of its efficiency and simplicity, being structured as a direct probabilistic relationship between the larger‐scale climatic variables and the local‐scale weather. Such a formulation offers a simpler alternative to the NHMM approach of using intermediate hidden weather state variables but is less capable of representing persistence introduced through Markovian assumptions in the NHMM. In the comparison presented here, we applied weather‐state‐based nonhomogeneous hidden Markov model and thek‐nearest neighbor bootstrap to estimate precipitation occurrences at a network of 30 rain gauge locations around Sydney, Australia. Our results suggest that both the models perform well in representing spatial variations while they show a lack in representing temporal dependence at scales longer than a few days as exhibited through wet spell length characteristics. Local‐scale features that are difficult to represent through the large‐scale climate predictors are, as expected, not reproduced by either approach.
Dynamic Changes in Brain Glucose and Lactate in Pericontusional Areas of the Human Cerebral Cortex, Monitored with Rapid Sampling On-Line Microdialysis: Relationship with Depolarisation-Like Events
Authors: Parkin Mark , Hopwood Sarah , Jones Deborah A , Hashemi Parastoo , Landolt Hans , Fabricius Martin , Lauritzen Martin , Boutelle Martyn G , Strong Anthony J
Published: February 2005

The pathophysiology of peri-lesion boundary zones in acute brain injury is highly dynamic, and it is now clear that spreading-depression-like events occur frequently in areas of cerebral cortex adjacent to contusions in the injured human brain. An automated method to assay microdialysate from peri-lesion cerebral cortex in 11 patients with intracranial haematomas requiring surgery was used. Perfusate (2 μL/min) flowed directly into a flow-injection system for assay of glucose and lactate at intervals typically of 30 secs each. Four channels of electrocorticogram (ECoG) were recorded from a subdural strip adjacent to the catheter. Several patterns of change in metabolites were identified in different time domains. Overall, the number of transient lactate events was significantly correlated with the number of glucose events ( r2=0.48, P=0.027, n=10). Progressive reduction in dialysate glucose was very closely correlated with the aggregate number of ECoG events ( r2=0.76, P=0.0004, n=11). It is proposed that the recently documented adverse impact of low dialysate glucose on clinical outcome may be because of recurrent, spontaneous spreading-depression-like events in the perilesion cortex.
Inhibition of Vascular Nitric Oxide after Rat Chronic Brain Hypoperfusion: Spatial Memory and Immunocytochemical Changes
Authors: de la Torre Jack C. , Aliev Gjumrakch
Published: February 2005

An aging rat model of chronic brain hypoperfusion (CBH) that mimics human mild cognitive impairment (MCI) was used to examine the role of nitric oxide synthase (NOS) isoforms on spatial memory function. Rats with CBH underwent bilateral common carotid artery occlusion (2-vessel occlusion (2-VO)) for either 26 or 8 weeks and were compared with nonoccluded sham controls (S-VO). The neuronal and endothelial (nNOS/eNOS) constitutive inhibitor nitro-L-arginine methyl ester (L-NAME) 20 mg/kg was administered after 26 weeks for 3 days to 2-VO and S-VO groups and spatial memory was assessed with a modified Morris watermaze test. Only 2-VO rats worsened their spatial memory ability after L-NAME. Electron microscopic immunocytochemical examination using an antibody against eNOS showed 2-VO rats had significant loss or absence of eNOS-containing positive gold particles in hippocampal endothelium and these changes were associated with endothelial cell compression, mitochondrial damage and heavy amyloid deposition in hippocampal capillaries and perivascular region. In the 8-week study, three groups of 2-VO rats were administered an acute dose of 7-NI, aminoguanidine or L-NIO, the relatively selective inhibitors of nNOS, inducible NOS and eNOS. Only rats administered the eNOS inhibitor L-NIO worsened markedly their watermaze performance ( P=0.009) when compared with S-VO nonoccluded controls. We conclude from these findings that vascular nitric oxide derived from eNOS may play a critical role in spatial memory function during CBH possibly by keeping cerebral perfusion optimal through its regulation of microvessel tone and cerebral blood flow and that disruption of this mechanism can result in spatial memory impairment. These findings may identify therapeutic targets for preventing MCI and treating Alzheimer's disease.
Effect of Caffeine on Cerebral Blood Flow Response to Somatosensory Stimulation
Authors: Meno Joseph R. , Nguyen Thien-son K. , Jensen Elise M. , Alexander West G. , Groysman Leonid , Kung David K. , Ngai Al C. , Britz Gavin W. , Winn H. Richard
Published: February 2005

Despite caffeine's wide consumption and well-documented psychoactive effects, little is known regarding the effects of caffeine on neurovascular coupling. In the present study, we evaluated the effects of caffeine, an adenosine receptor antagonist, on intracerebral arterioles in vitro and subsequently, on the pial circulation in vivo during cortical activation induced by contralateral sciatic nerve stimulation (SNS). In our in vitro studies, we utilized isolated intracerebral arterioles to determine the effects of caffeine (10 or 50 μmol/L) on adenosine-induced vasodilatation. At the lower concentration, caffeine was without effect, but at the higher concentration, caffeine produced significant attenuation. In our in vivo studies, we determined the cerebrospinal fluid (CSF) caffeine concentrations at 15, 30, and 60 mins after intravenous administration of 5, 10 and 40 mg/kg. At the latter two concentrations, CSF levels exceeded 10 μmol/L. We then evaluated the pial arteriolar response during cortical activation caused by contralateral SNS after administering caffeine intravenously (0, 5, 10, 20 30, and 40 mg/kg). The pial circulation was observed through a closed cranial window in chloralose-anesthetized Sprague—Dawley rats. The contralateral sciatic nerve was isolated, positioned on silver electrodes and stimulated for 20 secs (0.20 V, 0.5 ms, and 5 Hz). Arteriolar diameter was quantified using an automated video dimension analyzer. Contralateral SNS resulted in a 23.8%±3.9% increase in pial arteriolar diameter in the hindlimb sensory cortex under control conditions. Intravenous administration of caffeine at the lowest dose studied (5 mg/kg) had no effect on either resting arteriolar diameter or SNS-induced vasodilatation. However, at higher doses (10, 20, 30, and 40 mg/kg, intravenously), caffeine significantly ( P<0.05; n=6) attenuated both resting diameter and cerebral blood flow (CBF) responses to somatosensory stimulation. Intravenous administration of theophylline (10, 20, and 40 mg/kg), another adenosine receptor antagonist, also significantly reduced SNS-induced vasodilatation in a dose-dependent manner. Hypercarbic vasodilatation was unaffected by either caffeine or theophylline. The results of the present study show that caffeine significantly reduces cerebrovascular responses to both adenosine and to somatosensory stimulation and supports a role of adenosine in the regulation of CBF during functional neuronal activity.
State Restructuring and the Scale Politics of Rural Water Governance in Bolivia
Authors: Perreault Thomas
Published: February 2005

Recent attempts to grant private concessions to water in Bolivia raise questions regarding the effects of the state's neoliberal restructuring on environmental governance. Like other Latin American states, Bolivia has enacted sweeping neoliberal reforms during the past two decades, including privatization of public sector industries, reduction of state services, and administrative decentralization. These reforms have been accompanied by constitutional reforms that recognized certain resource and political rights on the part of Bolivia's indigenous and campesino peoples. This paper examines the reregulation and rescaling of rural water management in Bolivia, and associated processes of mobilization on the part of peasant irrigators aimed at countering state reforms. Although traditional resource rights of peasant irrigators are strengthened by cultural aspects of constitutional reforms, rural livelihoods are undermined by economic liberalization. The paper examines the implications and contradictions of neoliberal reforms for rural water management in highland Bolivia. These processes are illustrated through a brief analysis of current organizational efforts on the part of peasant irrigators.
Mining Mountains: Neoliberalism, Land Tenure, Livelihoods, and the New Peruvian Mining Industry in Cajamarca
Authors: Bury Jeffrey
Published: February 2005

Peru has been transformed over the course of the past decade into a neoliberal, mineral-based, export-oriented, country. The author evaluates the neoliberal transformation of the country in three parts. First he examines the economic and political transformation of the country in the early 1990s, particularly in terms of how the Peruvian state and economy were rapidly restructured according to neoliberal principles. He then illustrates how, both through privatization and through transnationalization, the mining sector has become a key element for future development opportunities. This discussion is then contextualised by an examination of how mining activities are affecting land-tenure patterns and livelihoods in the Cajamarca region of Peru. In particular, drawing upon case-study research, the author evaluates how Minera Yanacocha's transnational gold-mining operations are transforming land-tenure institutions, land values, and the spatial distribution of land-use patterns throughout the region. In addition, he evaluates how livelihoods are being transformed in response to Minera Yanacocha's activities through an examination of changing household access to natural, human, social, and economic resources.
Agrarian Moral Economies and Neoliberalism in Brazil: Competing Worldviews and the State in the Struggle for Land
Authors: Wolford Wendy
Published: February 2005

The 1990s was the decade of neoliberalism in Brazil. During the successive administrations of President Fernando Henrique Cardoso (1995–2003), public enterprises were privatized, import tariffs were slashed, regional free-trade markets were established, and fiscal discipline was prioritized in an attempt to control a massive public debt. As his first term progressed, however, Cardoso was forced to respond to the insistent popular demand for reform of the country's inequitable land-tenure structure. The issue became increasingly visible in the 1990s because of the strength of a grassroots social movement, the Movement of Landless Workers (MST). In response to the demands for agrarian reform, the government offered its support for an essentially neoliberal, market-based alternative to state-led distribution—an alternative favored by official development organizations throughout the Third World at this time. In this paper, I argue that the support for a market-led agrarian reform privileged the agrarian elite in Brazil and delegitimated the MST's struggle, not only because it reinforced the elite's claim to land but also because it legitimated the elite's particular interpretation of productivity and property rights. The claims put forward both by the agrarian elite and by the MST members in the southern state of Santa Catarina derive from what can usefully be considered ‘agrarian moral economies’.
Nitrolinoleic acid: An endogenous peroxisome proliferator-activated receptor γ ligand
Authors: Schopfer Francisco J. , Lin Yiming , Baker Paul R. S. , Cui Taixing , Garcia-Barrio Minerva , Zhang Jifeng , Chen Kai , Chen Yuqing E. , Freeman Bruce A.
Published: February 2005

Nitroalkene derivatives of linoleic acid (nitrolinoleic acid, LNO
2
) are formed via nitric oxide-dependent oxidative inflammatory reactions and are found at concentrations of ≈500 nM in the blood of healthy individuals. We report that LNO
2
is a potent endogenous ligand for peroxisome proliferator-activated receptor γ (PPARγ;
K
i
≈133 nM) that acts within physiological concentration ranges. This nuclear hormone receptor (PPARγ) regulates glucose homeostasis, lipid metabolism, and inflammation. PPARγ ligand activity is specific for LNO
2
and not mediated by LNO
2
decay products, NO donors, linoleic acid (LA), or oxidized LA. LNO
2
is a significantly more robust PPARγ ligand than other reported endogenous PPARγ ligands, including lysophosphatidic acid (16:0 and 18:1), 15-deoxy-Δ
12,14
-PGJ
2
, conjugated LA and azelaoyl-phosphocholine. LNO
2
activation of PPARγ via CV-1 cell luciferase reporter gene expression analysis revealed a ligand activity that rivals or exceeds synthetic PPARγ agonists such as rosiglitazone and ciglitazone, is coactivated by 9
cis
-retinoic acid and is inhibited by the PPARγ antagonist GW9662. LNO
2
induces PPARγ-dependent macrophage CD-36 expression, adipocyte differentiation, and glucose uptake also at a potency rivaling thiazolidinediones. These observations reveal that NO-mediated cell signaling reactions can be transduced by fatty acid nitration products and PPAR-dependent gene expression.