bluuebunny/crossref_metadata_2025 huggingface dataset:
Quality adjusted survival analysis
Authors: Glasziou P. P. , Simes R. J. , Gelber R. D.
Published: April 2007

We present a technique, quality adjusted survival analysis, for the analysis of controlled trials where patients may experience several health states which differ in their quality of life. When the data are censored, a survival analysis of the quality adjusted life years achieved may involve informative censoring, and produce biased estimates. To overcome this, we partition the survival curve; the resulting areas, which represent the mean time in each state, are multiplied by utility weights to provide an unbiased estimate of (restricted) quality adjusted survival.

If the appropriate weights are in doubt, the results are best presented as a threshold analysis over the utility weights, allowing individual recommendation to be read from a simple graph. The certainty of the conclusions can be presented as confidence bands on the threshold line. The techniques are illustrated with a re‐analysis of a large three‐arm trial of adjuvant chemoendocrine therapy for stage II breast cancer in post‐menopausal women. This shows that if the value of time spent in toxicity is greater than the time spent in relapse, we can be 95 per cent confident that chemoendocrine therapy is the preferred option.
Design methods for some dose‐response models
Authors: Strijbosch Leo W. G. , Does Ronald J. M. M. , Albers Willem
Published: April 2007

A recently described design method for one‐parameter biomedical models such as limiting or serial dilution assays is generalized to two‐parameter models for which the dose‐response relationship can be expressed as a linear regression model with parameters α (intercept) and β (slope). Design formulae are proposed for three different cases in which prior information about the unknown regression parameters α and β is available (α known, β known and neither known, respectively). A suitable transformation of the two‐parameter model enables the direct application of the one‐parameter design method to the first two cases, while the third needs more advanced considerations. Two experimental designs, taken from the literature, are reproduced as closely as possible using the methods described, thus showing under which circumstances these designs are suitable.
Some statistical issues in studies of the epidemiology of aids
Authors: Jewell Nicholas P.
Published: April 2007

Analyses of studies of the epidemiology and natural history of infection with the Human Immunodeficiency Virus and subsequent onset of AIDS are complicated by many statistical issues. Several such problems are associated with the nature of data collection which is often incomplete. Here we briefly survey some of the statistical methods that have been developed to meet the needs of analysis of AIDS data. In particular, we consider projection of the number of future cases, and estimation and identification of two key epi‐demiological unknowns, namely the properties of the incubation distribution and those of the infectivity associated with transmission.
Group sequential designs using a family of type I error probability spending functions
Authors: Hwang Irving K. , Shih Weichung J. , De Cani John S.
Published: April 2007

Performing planned or unplanned interim analyses on accumulating data in clinical trials is a frequent practice. In this paper, we propose a general one‐parameter family of type I error probability spending functions to construct customized group sequential boundaries with unequal increments in information time. This proposed family generalizes the spending functions of Lan and DeMets1 and Kim and DeMets.2 We give an example to illustrate the use of this family.
Estimation of the linear relationship between the measurements of two methods with proportional errors
Authors: Linnet Kristian
Published: April 2007

The linear relationship between the measurements of two methods is estimated on the basis of a weighted errors‐in‐variables regression model that takes into account a proportional relationship between standard deviations of error distributions and true variable levels. Weights are estimated by an iterative procedure. As shown by simulations, the regression procedure yields practically unbiased slope estimates in realistic situations. Standard errors of slope and location difference estimates are derived by the jackknife principle. For illustration, the linear relationship is estimated between the measurements of two albumin methods with proportional errors.
Survival time models for analysing drug combination treatments
Authors: Kübler Jürgen , Schumacher Martin
Published: April 2007

Several relative risk models for survival time data in drug combination therapy are derived and their properties are discussed. The main intention of this paper is to clarify the differences among the models in order to help to choose the appropriate one in a given situation. The models are motivated by discussing their relation to well‐known physiological concepts. In an example of two‐drug treatment the models are compared with each other. For this chemotherapy animal survival study, dose‐risk surfaces are fitted and optimal drug combinations are estimated. Methods for checking the model assumptions are mentioned.
European concerted action on offshore wind energy deployment: inventory and analysis of power transmission barriers in eight member states
Authors: Woyte Achim , Gardner Paul , Snodin Helen
Published: April 2007

The European Concerted Action for Offshore Wind Energy Deployment (COD) was carried out by eight sea‐bordering European Union member states, with the objective to remove not explicitly technical barriers to offshore wind energy. Within the COD, an inventory of relevant aspects affecting the grid integration of offshore wind energy on a large scale in the eight countries has been made. Collected data items for this inventory are national plans and prospects for offshore wind energy, information about the transmission system, possibilities for grid connection, aspects of the grid codes, balancing, connection and energy pricing. The comprehensive COD reports were published and presented in October 2005 during the Copenhagen Offshore wind conference. This paper provides a short description of the situation for each country. Thereafter, country‐specific information is grouped based on geography and membership in a synchronous zone. Additionally, a view is developed on the desirable facilities for the trans‐European exchange of power from large wind farms. Finally, we elaborate overall conclusions in order to arrive at generalized observations, recommendations for policy makers and issues that will emerge in the near future. As a general conclusion, many things need to be done on a technical level in order to integrate large amounts of offshore wind power into our power systems. However, none of these measures is technically unknown. Therefore, the feasibility of integrating large amounts of offshore wind power is mainly a question of finance and hence based on political decisions. Copyright © 2007 John Wiley & Sons, Ltd.
Effects of a fat load and exercise on asymptomatic VLCAD deficiency
Authors: Spiekerkoetter U.
Published: April 2007

The patient was identified via family screening at the age of 3 years when very long‐chain acyl‐CoA dehydrogenase (VLCAD) deficiency was diagnosed in his sister by newborn screening. Enzyme and molecular analyses confirmed VLCAD‐deficiency (VLCADD). Until the age of 8 years no severe illnesses occurred and the patient was completely asymptomatic without a fat‐reduced and fat‐modified diet. On regular follow‐up, creatine kinase (CK) and liver transaminases were always in the normal range. A long‐chain fat load with 1.5 g/kg body weight did not result in clinical symptoms, nor in elevation of CK or liver transaminases. At the age of 8 years, the patient for the first time complained of recurrent muscle pain after exercise. CK concentrations were elevated up to 20 000 U/L during one of these episodes. Medium‐chain fat was supplemented. With a medium‐chain fat‐rich meal directly before exercise, muscle pain after exercise clearly decreased. In asymptomatic mild VLCADD, a fat‐reduced diet may not be necessary, whereas in later infancy and adolescence, strenuous physical exercise may require additional energy from medium‐chain fat.
DNA-Reparaturdefekte und Krebs
Authors: Digweed M. , Sperling K.
Published: April 2007

Die Zellen des lymphatischen Systems sind durch das hohe Ausmaß somatischer Rekombination und die damit verbundene Hypermutabilität gekennzeichnet. Dabei werden DNA-Doppelstrang-Brüche (DSB) induziert und „repariert“, wobei die beteiligten Gene auch in die allgemeine Reparatur von DSB einbezogen sind. Keimbahnmutationen in diesen Genen gehen mit einem besonders hohen Risiko für Lymphome einher. Diese genetisch bedingten Krankheiten sowie die charakteristischen somatischen Mutationen in Lymphomen haben wesentlich zum Verständnis von DNA-Reparaturdefekten bei der Kanzerogenese beigetragen.
ERp57 interacts with conserved cysteine residues in the MHC class I peptide‐binding groove
Authors: Antoniou Antony N. , Santos Susana G. , Campbell Elaine C. , Lynch Sarah , Arosa Fernando A. , Powis Simon J.
Published: April 2007

The oxidoreductase ERp57 is a component of the major histocompatibility complex (MHC) class I peptide‐loading complex. ERp57 can interact directly with MHC class I molecules, however, little is known about which of the cysteine residues within the MHC class I molecule are relevant to this interaction. MHC class I molecules possess conserved disulfide bonds between cysteines 101–164, and 203–259 in the peptide‐binding and α3 domain, respectively. By studying a series of mutants of these conserved residues, we demonstrate that ERp57 predominantly associates with cysteine residues in the peptide‐binding domain, thus indicating ERp57 has direct access to the peptide‐binding groove of MHC class I molecules during assembly.
Evidence of native starch degradation with human small intestinal maltase‐glucoamylase (recombinant)
Authors: Ao Zihua , Quezada-Calvillo Roberto , Sim Lyann , Nichols Buford L. , Rose David R. , Sterchi Erwin E. , Hamaker Bruce R.
Published: April 2007

Action of human small intestinal brush border carbohydrate digesting enzymes is thought to involve only final hydrolysis reactions of oligosaccharides to monosaccharides. In vitro starch digestibility assays use fungal amyloglucosidase to provide this function. In this study, recombinant N‐terminal subunit enzyme of human small intestinal maltase‐glucoamylase (rhMGAM‐N) was used to explore digestion of native starches from different botanical sources. The susceptibilities to enzyme hydrolysis varied among the starches. The rate and extent of hydrolysis of amylomaize‐5 and amylomaize‐7 into glucose were greater than for other starches. Such was not observed with fungal amyloglucosidase or pancreatic α‐amylase. The degradation of native starch granules showed a surface furrowed pattern in random, radial, or tree‐like arrangements that differed substantially from the erosion patterns of amyloglucosidase or α‐amylase. The evidence of raw starch granule degradation with rhMGAM‐N indicates that pancreatic α‐amylase hydrolysis is not a requirement for native starch digestion in the human small intestine.
Three‐dimensional transrectal ultrasonography in adolescent patients with polycystic ovarian syndrome
Authors: Sun Li , Fu Qingzhao
Published: April 2007

Objectives: To evaluate the diagnostic value of 3‐dimensional transrectal ultrasonography (3D‐TRS) in adolescent patients with polycystic ovarian syndrome (PCOS). Methods: Ovarian follicle number, ovarian volume, ovarian stromal area, total ovarian area, and stromal area to total area ratio (S/A) were evaluated using 3D‐TRS in 75 amenorrheic, oligomenorrheic, or asymptomatic virgin patients and 25 healthy controls. Serum biochemical markers of PCOS were assayed during the early follicular phase of the menstrual cycle in menstruating patients and controls, and on a randomly selected day in amenorrheic patients. Results: When assessing the delicate structure of the ovary in virgin patients, 3D‐TRS was convenient, accurate, specific, sensitive, and more reliable overall than transabdominal ultrasonography. Ovarian stromal area and S/A ratio were significantly greater in patients with PCOS than in controls, and also in the patients who had ultrasonically diagnosed polycystic ovaries without clinical or biochemical evidence of PCOS. The S/A ratio was the studied variable most significantly correlated with androgen levels. Conclusions: These findings indicated that, in adolescent patients, 3D‐TRS combined with transabdominal ultrasonography can improve the precision of the diagnosis of PCOS. The S/A ratio may become the ultrasonographic diagnostic marker for PCOS.
What is the meaning of these constant interruptions?
Authors: HUTTON GRAHAM , WRIGHT JOEL
Published: April 2007

Asynchronous exceptions, orinterrupts, are important for writing robust, modular programs, but are traditionally viewed as being difficult from a semantic perspective. In this article, we present a simple, formally justified, semantics for interrupts. Our approach is to show how a high-level semantics for interrupts can be justified with respect to a low-level implementation, by means of a compiler and its correctness theorem. In this manner we obtain two different perspectives on the problem, formally shown to be equivalent, which gives greater confidence in the correctness of our semantics.
Zoledronat-assoziierte terminale Niereninsuffizienz und Hypokalzämie
Authors: Ramazzina  , Zysset Aschmann  , Kummer  , Rätz Bravo  , Bodmer
Published: April 2007

Bei einer 81-jährigen Frau mit vorbekannter, jahrelang stabiler mittelschwerer chronischer Niereninsuffizienz wurde die Diagnose eines multiplen Myeloms gestellt. Nach einer initialen Chemotherapie wurde mit einer monatlichen intravenösen Pamidronat-Therapie mit 90 mg begonnen. Nach vier Jahren problemlos tolerierter Therapie erfolgte die Umstellung auf Zoledronat, 4 mg i.v. alle vier Wochen. Darunter kam es innerhalb von knapp einem Jahr zu einem erstmaligen Kreatininanstieg und im Verlauf der folgenden Monate zur Entwicklung einer terminalen Niereninsuffizienz. Bei Hospitalisation zeigte sich gleichzeitig eine schwere, asymptomatische Hypokalzämie. Nierenbioptisch liess sich eine schwere tubulointerstitielle Nephropathie nachweisen, vereinbar mit medikamentös-toxischem Schaden. Eine prärenale wie auch postrenale Ursache der Niereninsuffizienz konnte, ebenso wie eine Myelomniere, ausgeschlossen werden. Die Diagnose einer Zoledronat-assoziierten terminalen Niereninsuffizienz wurde gestellt und eine Behandlung mittels Hämodialyse eingeleitet. Die Therapie der Hypokalzämie wurde pragmatisch mit Kalzium und Vitamin D3 durchgeführt. Bis heute, zwei Jahre nach Diagnosestellung, blieb die Patientin dialysepflichtig.
Belastungsabhängige Leistenschmerzen bei chronischer HIV-1-Infektion
Authors: Bremi  , Günthard  , Forster
Published: April 2007

Bei einem 38-jährigen Mann mit bekannter langjähriger HIV-1-Infektion wurde als Ursache belastungsabhängiger Leistenschmerzen links eine fortgeschrittene Femurkopfnekrose gefunden. Osteonekrosen treten bei HIV-1-Infizierten gehäuft auf, und sie werden oft sogar multifokal angetroffen. Bei lokalisierten Knochen- und Gelenkschmerzen bei langjährig HIV-infizierten Menschen muss deswegen neben infektiösen Ursachen immer auch die Möglichkeit einer Osteonekrose erwogen werden.
Simultane Analysen auf Schüler- und Klassenebene
Authors: Lüdtke Oliver , Trautwein Ulrich , Schnyder Inge , Niggli Alois
Published: April 2007

Zusammenfassung. Daten in der pädagogisch-psychologischen Forschung weisen häufig eine Mehrebenenstruktur auf: Schüler sind geschachtelt innerhalb von Schulen und Klassen. Dies muss berücksichtigt werden, wenn Schüler Merkmale ihres schulischen Kontextes (z.B. Lehrer, Schulklima) auf mehreren Dimensionen beurteilen sollen und dann die Einschätzungen der Schüler sowohl auf der Individual- als auch aggregiert auf der Klassenebene in weiteren Analysen verwendet werden. Die konfirmatorische Mehrebenen-Faktorenanalyse ist ein Verfahren, das zur Analyse solcher Daten besonders gut geeignet, bislang jedoch noch nicht ausreichend bekannt ist. Die vorliegende Arbeit demonstriert anhand eines Datensatzes aus der Hausaufgabenforschung (1712 Schüler in 98 Klassen) die Grundlagen und Anwendung der Mehrebenen-Faktorenanalyse. Sowohl auf Schüler- als auch auf Klassenebene ließen sich die drei Faktoren Qualität der Hausaufgaben, die Kontrolle der Hausaufgaben sowie die effektive Zeitnutzung im Französisch-Unterricht erwartungsgemäß empirisch trennen. Darüber hinaus ließ sich sowohl auf der Schüler- als auch der Klassenebene ein positiver Effekt der Qualität der Hausaufgaben und der effektiven Zeitnutzung auf die selbst berichtete Anstrengung bei der Bearbeitung der Hausaufgaben nachweisen.
Entwicklung und Stabilität motorischer Fähigkeiten vom Vorschul- bis ins frühe Erwachsenenalter
Authors: Ahnert Jutta , Schneider Wolfgang
Published: April 2007

Zusammenfassung. Angesichts der Forschungsbefunde zum veränderten Bewegungsverhalten und der Zunahme motorischer Defizite der heute Heranwachsenden gewinnt die Frage nach der Stabilität motorischer Fähigkeiten für das frühzeitige Erkennen von ungeschickten und motorisch schwachen Kindern und Jugendlichen immer stärker an Bedeutung. Der bisherige Forschungsstand zur Stabilität motorischer Leistungsfähigkeit beschränkt sich bisher jedoch fast ausschließlich auf retrospektive Studien oder aber auf Längsschnittstudien, die nur einen begrenzten Lebensabschnitt erfassen. Die hier analysierten Daten zur motorischen Entwicklung wurden im Rahmen der Münchner Längsschnittstudie zur Genese individueller Kompetenzen (LOGIK) an 152 Mädchen und Jungen im Alter von 4, 5, 6, 8, 10, 12 und 23 Jahren erhoben. Aus den Befunden geht hervor, dass der Entwicklungsverlauf motorischer Fähigkeiten ab dem späten Grundschulalter stark vom Geschlecht und von der beanspruchten motorischen Fähigkeit abhängig ist. Es zeigen sich bereits im Vorschulalter moderate Stabilitätskoeffizienten zu den motorischen Leistungen im frühen Erwachsenenalter, die ab dem Grundschulalter auf substanzielle Werte ansteigen. Dies bedeutet, dass bereits im Kindesalter identifizierte individuelle Unterschiede in der motorischen Leistungsfähigkeit auch bis ins frühe Erwachsenenalter erhalten bleiben.
Impact of climate forcing on ecosystem processes in the North Pacific Subtropical Gyre
Authors: Corno Guido , Karl David M. , Church Matthew J. , Letelier Ricardo M. , Lukas Roger , Bidigare Robert R. , Abbott Mark R.
Published: April 2007

Measurements at the Hawaii Ocean Time‐series (HOT) Station ALOHA (22°45′N, 158°W) have revealed a significant, approximately 50% increase in euphotic zone depth‐integrated rates of primary production (PP; mol C fixed m−2 d−1) based on in situ 14C experiments. The character of the nearly two‐decade increasing trend in PP was punctuated by several abrupt episodes that coincided with changes in the El Niño/Southern Oscillation (ENSO), and the Pacific Decadal Oscillation (PDO) climate indices, or both. In contrast to the observed increase in rates of PP, the PP per unit chlorophyll a (mol C fixed mol chl a−1 d−1), a measure of the biomass‐normalized production, was relatively constant, whereas PP per unit solar radiation (mol C fixed mol quanta−1), a measure of the efficiency of light utilization, varied in synchrony with the temporal trend in PP. Coincident with variations in PP, the HOT program core data sets also revealed changes in mixed‐layer depth, upper ocean stratification, inorganic nutrients, phototrophic microbial abundances and pigment inventories. These time‐series data suggest that the ENSO/PDO may control upper ocean stratification and vertical nutrient delivery into the euphotic zone at Sta. ALOHA, thereby influencing the composition of the plankton assemblage and altering rates of PP and particulate matter export.
Amplification of turbulent exchange over wide Arctic leads: Large‐eddy simulation study
Authors: Esau I. N.
Published: April 2007

Leads (narrow openings in the sea ice cover) are perhaps the most pronounced examples of heat islands naturally occurring on Earth. Large air‐water temperature differences induce strong turbulent convection. In addition, large ice‐water temperature differences induce more regular, breeze‐like circulation at ice edges. Both the turbulent convection and the breeze result in intensive turbulent heat exchange between the ocean and the atmosphere. This study describes a series of turbulence‐resolving experiments with the Large Eddy Simulation Nansen Center Improved Code (LESNIC). The numerical experiments quantify the turbulent heat exchange over leads of different widths. Contrary to the expected gradual decrease of the surface heat flux per unit area of open water, a strong amplification of the heat flux has been discovered for certain leads. This amplification results from a positive feedback between the horizontal entrainment of cool air in breeze and the turbulent heat exchange. Gradual reduction of the turbulent exchange for wider leads is thought to be due to development of self‐organized structures in the convection. Pressure anomalies induced by the convective overturning could be comparable with the pressure anomalies due to the surface temperature difference. Their superposition limits the penetration of the cold breeze into the lead area. Without the horizontal entrainment, the near‐surface temperature rises, reducing the average turbulent fluxes. In addition, the structures use the available kinetic energy to drive convective overturning. It also reduces the near‐surface velocity and therefore fluxes. The maximum heat flux over open water was obtained for 2 km to 4 km leads. The maximum flux exceeds five‐fold the flux in the homogeneous convection case. The revealed flux enhancement may have significant impact on the Arctic climate and more generally on the climate of urban areas and other heat islands. Therefore direct confirmation of the results from observational campaigns is urgently needed.
Summertime observations of HONO, HCHO, and O3 at the summit of Whiteface Mountain, New York
Authors: Zhou Xianliang , Huang Gu , Civerolo Kevin , Roychowdhury Utpal , Demerjian Kenneth L.
Published: April 2007

HONO, HCHO, and O3 concentrations were measured at the summit of Whiteface Mountain, New York, during the summer of 1999. Concentrations were in the range of ≤5–400 pptv with a median of 27 pptv and a mean of 46 pptv for HONO, in the range of ≤30–6170 pptv with a median of 1260 pptv and a mean of 1340 pptv for HCHO, and in the range of 20–105 ppbv with a median of 51 ppbv and a mean of 49 ppbv for O3. The daily HOx productions from the photolysis of O3, HONO, and HCHO were 6.1, 2.8, and 1.9 ppbv d−1, respectively, contributing 57, 26, and 17% to the overall daily radical budget from these precursors. Significant diurnal variation of average HONO concentrations was observed, with a late morning maximum and a late afternoon/early evening minimum. HNO3 photolysis on the mountain slope surfaces is proposed as the major daytime source for HONO, sustaining the majority of the observed daytime HONO concentrations against its photolytic loss. The daytime HONO/NOx ratio was also found to be high, ∼0.33 between 0800 and 1600 LT, suggesting that the transport of HONO from the ground surface to the observation height should be short, perhaps limited to the top portion of the mountain slope. The late afternoon HONO concentrations (∼27 pptv) may be considered as typical daytime HONO concentration in the aloft air mass not influenced by surface processes. While particulate nitrate photolysis may contribute significantly as a HONO source, more HONO formation/transport mechanisms are still required to account for the majority of the observed HONO concentration. HCHO concentrations exhibited only a small diurnal variation, with daytime concentrations slightly higher than nighttime concentration. HCHO was mainly transported to the site rather than produced locally from the biogenic photooxidation. O3 concentrations exhibited a diurnal variation that was similar to but more pronounced than HCHO, suggesting that the daytime in situ O3 photochemical production was small compared to its loss through photolysis and dry deposition.
Evaluation of modeled cloud properties against aircraft observations for air quality applications
Authors: Zhang Junhua , Gong Wanmin , Leaitch W. Richard , Strapp J. Walter
Published: April 2007

Cloud microphysical properties are critical for simulating cloud processing of gases and aerosols in air quality models. In this study, cloud liquid water contents (LWC) predicted from a meteorological model at two horizontal resolutions (15 and 2.5 km) are evaluated against aircraft observations during the 2004 International Consortium for Atmospheric Research on Transport and Transformation (ICARTT) campaign. A point‐by‐point comparison along flight tracks shows good model‐observation correlation for temperature and humidity but poor correlation for LWC due to the mismatch in timing and positioning of the clouds between model simulations and observations. Thus a statistical approach is used to compare properties of modeled and observed clouds over the flight domain. The model captures the observed vertical variation of LWC for the towering cumulus (TCu) cases and reproduces the observed variation of LWC from flight to flight independent of cloud types. The model is able to distinguish the difference in the mean and standard deviation of LWC between stratocumulus (SCu) and TCu. However, the “in‐cloud” LWC values were generally overpredicted by the model at both resolutions. For SCu, the overprediction is 99% and 45% for the 15‐ and 2.5‐km resolution simulations, respectively, while the overprediction for TCu is slightly smaller at 74% for the 15‐km resolution and 24% for the 2.5‐km resolution model simulations. The SCu observations were scaled up to enable comparisons at the model‐grid scales for these flights. This comparison also shows overpredictions of LWC by the model, although the overprediction is smaller for the model at 15‐km resolution.
Visible and near‐infrared multispectral analysis of rocks at Meridiani Planum, Mars, by the Mars Exploration Rover Opportunity
Authors: Farrand W. H. , Bell J. F. , Johnson J. R. , Jolliff B. L. , Knoll A. H. , McLennan S. M. , Squyres S. W. , Calvin W. M. , Grotzinger J. P. , Morris R. V. , Soderblom J. , Thompson S. D. , Watters W. A. , Yen A. S.
Published: April 2007

Multispectral measurements in the visible and near infrared of rocks at Meridiani Planum by the Mars Exploration Rover Opportunity's Pancam are described. The Pancam multispectral data show that the outcrops of the Burns formation consist of two main spectral units which in stretched 673, 535, 432 nm color composites appear buff‐ and purple‐colored. These units are referred to as the HFS and LFS spectral units based on higher and lower values of 482 to 535 nm slope. Spectral characteristics are consistent with the LFS outcrop consisting of less oxidized, and the HFS outcrop consisting of more oxidized, iron‐bearing minerals. The LFS surfaces are not as common and appear, primarily, at the distal ends of outcrop layers and on steep, more massive surfaces, locations that are subject to greater eolian erosion. Consequently, the HFS surfaces are interpreted as a weathering rind. Further inherent spectral differences between layers and between different outcrop map units, both untouched and patches abraded by the rover's Rock Abrasion Tool, are also described. Comparisons of the spectral parameters of the Meridiani outcrop with a set of laboratory reflectance measurements of Fe3+–bearing minerals show that the field of outcrop measurements plots near the fields of hematite, ferrihydrite, poorly crystalline goethite, and schwertmannite. Rind and fracture fill materials, observed intermittently at outcrop exposures, are intermediate in their spectral character between both the HFS and LFS spectral classes and other, less oxidized, surface materials (basaltic sands, spherules, and cobbles).
Dust deposition on the Mars Exploration Rover Panoramic Camera (Pancam) calibration targets
Authors: Kinch Kjartan M. , Sohl‐Dickstein Jascha , Bell James F. , Johnson Jeffrey R. , Goetz Walter , Landis Geoffrey A.
Published: April 2007

The Panoramic Camera (Pancam) on the Mars Exploration Rover mission has acquired in excess of 20,000 images of the Pancam calibration targets on the rovers. Analysis of this data set allows estimates of the rate of deposition and removal of aeolian dust on both rovers. During the first 150–170 sols there was gradual dust accumulation on the rovers but no evidence for dust removal. After that time there is ample evidence for both dust removal and dust deposition on both rover decks. We analyze data from early in both rover missions using a diffusive reflectance mixing model. Assuming a dust settling rate proportional to the atmospheric optical depth, we derive spectra of optically thick layers of airfall dust that are consistent with spectra from dusty regions on the Martian surface. Airfall dust reflectance at the Opportunity site appears greater than at the Spirit site, consistent with other observations. We estimate the optical depth of dust deposited on the Spirit calibration target by sol 150 to be 0.44 ± 0.13. For Opportunity the value was 0.39 ± 0.12. Assuming 80% pore space, we estimate that the dust layer grew at a rate of one grain diameter per ∼100 sols on the Spirit calibration target. On Opportunity the rate was one grain diameter per ∼125 sols. These numbers are consistent with dust deposition rates observed by Mars Pathfinder taking into account the lower atmospheric dust optical depth during the Mars Pathfinder mission.
Bounds on the viscosity coefficient of continental lithosphere from removal of mantle lithosphere beneath the Altiplano and Eastern Cordillera
Authors: Molnar Peter , Garzione Carmala N.
Published: April 2007

The rapid rise of the central Andean plateau between ∼10 and 6.8 Ma implies that mantle lithosphere, including eclogitized lower crust, was removed from beneath the region in that time interval; we infer from that removal that the average viscosity coefficient of mantle lithosphere was quite low when removal occurred. Using scaling laws for the growth of perturbations to the thickness of a dense layer over an inviscid substratum (Rayleigh‐Taylor instability), we place bounds on the average viscosity coefficient for central Andean lithosphere. When compared with laboratory measurements of flow laws for olivine and eclogite, the allowed range of viscosity coefficients yields bounds on the temperature of ∼500–800°C at the Moho beneath this region and suggests that mean stresses across mantle lithosphere during continental deformation are less than ∼50 MPa. This range of temperature is comparable with, if a slightly lower than, we might expect for lithosphere approximately doubled in thickness and not yet equilibrated with the doubled crustal radioactivity. The mean deviatoric stress is comparable to that associated with stresses that drive plates and hence shows that lithospheric material is not too strong to prevent removal of its mantle part.
The Strength of Weak Lock-Ins: The Renewal of the Westmünsterland Textile Industry
Authors: Hassink Robert
Published: April 2007

Modern theoretical concepts in economic geography are used to try to explain the positive sides of geographical clustering of industries. Of the few theoretical concepts which are used to try to explain the negative sides of clustering, that is, the decline of old industrial areas, evolutionary regional economics, in general, and the lock-in concept, in particular, are promising ones. Lock-ins have been furthest developed by Grabher in his study on the steel and coal-mining complex in the Ruhr Area, Germany. They can be considered as thick interfirm, institutional, and cognitive tissues aimed at preserving existing industrial structures and therefore unnecessarily slowing down industrial renewal. It is particularly in regions with political lock-ins in which the legacy of manufacturing endures. On the basis of a study on the restructuring of the textile industry in Westmünsterland in Germany, in this paper I analyse whether these kinds of lock-ins can also be observed in regions with strong concentrations of the textile industry, an industry that strongly differs from the above-mentioned steel and coal-mining complex. I show that the impact of lock-ins can be regarded as relatively weak in the textile region of Westmünsterland. Partly because of that, industrial renewal has been relatively successful, which in turn has kept lock-ins weak.
Measuring and Interpreting the Effects of a Public-Sector-Led Urban Renewal Project on Housing Prices—An Empirical Study of a Comprehensive Development Area Zone Developed upon ‘Taking’ in Hong Kong
Authors: Lai Lawrence W C , Chau Kwong Wing , Yiu Edward C Y , Wong Kelvin S K , Wong Wah Sang , Chan Pearl Y L
Published: April 2007

Statutory zoning, as a regulatory tool, is generally considered as a means to introduce and maximize positive externalities and to preempt and internalize negative externalities; thence the land value of the regulated land and its immediate neighbourhood is enhanced. Yet, empirical evidence of the effects of zoning on land values has been conflicting. This paper empirically evaluates the panel data for a district in which two large-scale commercial properties have been developed in a comprehensive development area (CDA) statutorily rezoned from commercial/residential status on land taken by compulsory purchase by a public urban renewal agency in Hong Kong. A price gradient analysis is used to test the effects of such rezoning. The results show that the effect of the new CDA zoning on the prices of housing surrounding the CDA is uncertain. The Pigovian argument for the positive effect of zoning is therefore refuted as a justification for the zone under investigation, and the meaning of the finding for urban renewal planning is discussed. Some urban design factors that may have contributed to the failure of the projects are also discussed.
Detecting Spatiotemporal Dynamic Landscape Patterns Using Remote Sensing and the Lacunarity Index: A Case Study of Haikou City, China
Authors: Tian Guangjin , Yang Zhifeng , Xie Yichun
Published: April 2007

Quantifying the landscape pattern and its dynamics is essential for the monitoring and assessment of the ecological consequences of urbanization. As one of the Special Economic Zones, Haikou is one of the fastest growing regions among all Chinese cities, owing to rapid real estate development. Using a GIS-based land-use dataset from 1986, 1996, and 2000, in combination with a lacunarity index, we attempt to quantify the spatial pattern in the Haikou metropolitan area. After the landscape structure changes over the periods 1986–96 and 1996–2000 are analyzed, a Markov conversion matrix is applied in order to study the sources and destinations of landscape dynamic changes. The lacunarity index is calculated in order to measure the landscape dynamics, with respect to several major land-use types, at a range of spatial scales. The findings indicate that the leapfrog development of real estate and the rapid economic growth of Haikou City have had a great impact on the dynamic landscape patterns. From 1986 to 1996 urban land expanded dramatically and clustered, while cropland was encroached upon and fragmented. From 1996 to 2000, after the government had implemented the strict cropland protection measures, urban expansion and cropland misuse were controlled to a large degree, and a lot of cropland was reclaimed in certain areas. We investigate the dynamic landscape pattern and process, and their implications in policy and economic development.
Human prion proteins with pathogenic mutations share common conformational changes resulting in enhanced binding to glycosaminoglycans
Authors: Yin Shaoman , Pham Nancy , Yu Shuiliang , Li Chaoyang , Wong Poki , Chang Binggong , Kang Shin-Chung , Biasini Emiliano , Tien Po , Harris David A. , Sy Man-Sun
Published: April 2007

Mutation in the prion gene
PRNP
accounts for 10–15% of human prion diseases. However, little is known about the mechanisms by which mutant prion proteins (PrPs) cause disease. Here we investigated the effects of 10 different pathogenic mutations on the conformation and ligand-binding activity of recombinant human PrP (rPrP). We found that mutant rPrPs react more strongly with N terminus-specific antibodies, indicative of a more exposed N terminus. The N terminus of PrP contains a glycosaminoglycan (GAG)-binding motif. Binding of GAG is important in prion disease. Accordingly, all mutant rPrPs bind more GAG, and GAG promotes the aggregation of mutant rPrPs more efficiently than wild-type recombinant normal cellular PrP (rPrP
C
). Furthermore, point mutations in
PRNP
also cause conformational changes in the region between residues 109 and 136, resulting in the exposure of a second, normally buried, GAG-binding motif. Importantly, brain-derived PrP from transgenic mice, which express a pathogenic mutant with nine extra octapeptide repeats, also binds more strongly to GAG than wild-type PrP
C
. Thus, several rPrPs with distinct pathogenic mutations have common conformational changes, which enhance binding to GAG. These changes may contribute to the pathogenesis of inherited prion diseases.
Clinical Significance of Olfactory Event‐Related Potentials Related to Orthonasal and Retronasal Olfactory Testing
Authors: Rombaux Philippe , Bertrand Bernard , Keller Thomas , Mouraux André
Published: April 2007

Objective: The purpose of this study was to evaluate the likelihood of recording olfactory event‐related potentials (OERPs) in patients with an olfactory dysfunction and to correlate the electrophysiological responses to orthonasal and retronasal olfactory testing.

Design/Materials and Methods: This was a prospective study of 65 patients with different origins of their olfactory loss. Orthonasal olfactory function was assessed with the “Sniffin' Sticks” test (orthonasal score; maximal score 48) and retronasal olfactory function with odorized powders presented intraorally (retronasal score; maximal score 20). The OERPs were obtained after presentation of 2‐phenyl ethyl alcohol, the selected olfactory stimulus. Causes of olfactory dysfunction included postinfectious olfactory loss (n = 15), head trauma (n = 26), nasal polyposis (n = 15), and mixed causes (idiopathic, toxic, drug induced) (n = 9).

Results: Based on orthonasal testing, 32 and 33 patients were diagnosed with anosmia and hyposmia, respectively. Twenty‐two patients from the hyposmic group demonstrated reliable OERPs. No OERPs were recorded in the anosmic group. Prevalence of OERPs in a cohort of patients with olfactory dysfunction was 33.8% (22 of 65). Median score (expressed as the percentage of the maximal score that could be obtained theoretically) in which OERPs were recorded was 50% (24 of 48) with orthonasal testing and 80% (16 of 20) with retronasal testing.

Conclusions: Patients with olfactory dysfunction usually demonstrate OERPs in one third of the cases. When olfactory dysfunction is in the range that separates normosmic subjects from anosmic patients, patients may have identifiable OERPs. Interpretation of both orthonasal and retronasal psychophysical olfactory testing should be supported by the recording of OERPs in a clinical setting.
Towards an artificial olfactory mucosa for improved odour classification
Authors: Gardner Julian W , Covington James A , Tan Su-Lim , Pearce Timothy C
Published: April 2007

Here, we report on a biologically inspired analytical system that represents a new concept in the field of machine olfaction. Specifically, this paper describes the design and fabrication of a novel sensor system, based upon the principle of ‘nasal chromatography’, which emulates the human olfactory mucosa. Our approach exploits the physical positioning of a series of broadly tuned sensors (equivalent to the olfactory epithelium) along the length of a planar chromatographic channel (analogous to the thin mucus coating of the nasal cavity) from which we extract both spatial (response magnitude) and temporal (retentive delay) sensor signals. Our study demonstrates that this artificial mucosa is capable of generating both spatial and temporal signals which, when combined, create a novel spatio-temporal representation of an odour. We believe that such a system not only offers improved odour discrimination over a sensor array-based electronic nose, but also shorter analysis times than conventional gas chromatographic techniques.
Altered reproductive success in rat pairs after environmental-like exposure to xenoestrogen
Authors: Fusani Leonida , Della Seta Daniele , Dessì-Fulgheri Francesco , Farabollini Francesca
Published: April 2007

Endocrine-disrupting compounds (EDCs) have the capacity of altering the normal function of the endocrine system. EDCs have shown dramatic effects on the reproductive biology of aquatic wildlife and may affect human reproduction as well. Studies on EDCs in mammalian species have often investigated the effects of short-term, high doses on male and female reproductive physiology. However, it is difficult to predict from such studies the effects of EDC on populations that are exposed to very low doses throughout their life via contaminated food and water. We studied the effects of EDC on mammalian reproduction with an environmental-like protocol where the endpoint is the reproductive success of exposed pairs. We focused on a subclass of EDC, the xenoestrogens, which mimic the action of natural oestrogen hormones. Male and female rats were exposed to low doses of the pure oestrogen, ethynyloestradiol, during development, by oral administration to their mothers during pregnancy and lactation, and to them until puberty. We evaluated the effects of the exposure on development and reproductive physiology of individuals, and on fertility and fecundity of pairs in which both members had been exposed to the same treatment. We found that low doses caused major reproductive deficits in the experimental animals. Very low, environmentally relevant doses did not have evident effects on exposed animals; however, the fecundity of exposed pairs was substantially altered. Environmentally relevant doses of xenoestrogens which have no evident physiological effects can alter the reproductive success of exposed pairs in natural populations.
Optics of the ultraviolet reflecting scales of a jumping spider
Authors: Land Michael F , Horwood Julia , Lim Matthew L.M , Li Daiqin
Published: April 2007

The jumping spiderCosmophasis umbraticafrom Singapore is strongly sexually dimorphic. The males, but not the females, reflect ultraviolet as well as green–orange light. The scales responsible for this are composed of a chitin–air–chitin sandwich in which the chitin layers are three-quarters of a wavelength thick and the air gap a quarter wavelength (whereλ=600 nm, the peak wavelength of the principal reflection maximum). It is shown that this configuration produces a second reflectance peak at approximately 385 nm, accounting for the observed reflection in the ultraviolet. Other scales have a similar thickness of chitin but lack the air gap and thus produce a dull purple reflection. This novel mechanism provides the spiders with two colour signals, both of which are important in mating displays.
Anti-predator defence and the complexity–stability relationship of food webs
Authors: Kondoh Michio
Published: April 2007

The mechanism for maintaining complex food webs has been a central issue in ecology because theory often predicts that complexity (higher the species richness, more the interactions) destabilizes food webs. Although it has been proposed that prey anti-predator defence may affect the stability of prey–predator dynamics, such studies assumed a limited and relatively simpler variation in the food-web structure. Here, using mathematical models, I report that food-web flexibility arising from prey anti-predator defence enhances community-level stability (community persistence and robustness) in more complex systems and even changes the complexity–stability relationship. The model analysis shows that adaptive predator-specific defence enhances community-level stability under a wide range of food-web complexity levels and topologies, while generalized defence does not. Furthermore, while increasing food-web complexity has minor or negative effects on community-level stability in the absence of defence adaptation, or in the presence of generalized defence, in the presence of predator-specific defence, the connectance–stability relationship may become unimodal. Increasing species richness, in contrast, always lowers community-level stability. The emergence of a positive connectance–stability relationship however necessitates food-web compartmentalization, high defence efficiency and low defence cost, suggesting that it only occurs under a restricted condition.
Eco‐evolutionary dynamics of communities and ecosystems
Authors: FUSSMANN G. F. , LOREAU M. , ABRAMS P. A.
Published: April 2007

We review theoretical and empirical studies to identify instances where evolutionary processes significantly affect the dynamics of populations, communities and ecosystems.

Early theoretical work on eco‐evolutionary dynamics was concerned with the effect of (co)evolution on the stability of two‐species predator–prey systems and the occurrence of character displacement in simple competitive systems. Today's theoretical ecologists are extending this work to study the eco‐evolutionary dynamics of multispecies communities and the functioning and evolutionary emergence of ecosystems.

In terms of methodology, eco‐evolutionary modelling has diversified from simple, locus‐based population genetic models to encompass models of clonal selection, quantitative trait dynamics and adaptive dynamics.

The few empirical studies on community dynamics that explicitly considered evolutionary processes support the view that evolutionary and ecological dynamics often occur on similar time‐scales, and that they co‐determine the dynamical behaviour of ecological communities.
Investigating the potential impacts of climate change on a marine turtle population
Authors: HAWKES L. A. , BRODERICK A. C. , GODFREY M. H. , GODLEY B. J.
Published: April 2007

Recent increases in global temperatures have affected the phenology and survival of many species of plants and animals. We investigated a case study of the effects of potential climate change on a thermally sensitive species, the loggerhead sea turtle, at a breeding location at the northerly extent of the range of regular nesting in the United States. In addition to the physical limits imposed by temperature on this ectothermic species, sea turtle primary sex ratio is determined by the temperature experienced by eggs during the middle third of incubation. We recorded sand temperatures and used historical air temperatures (ATs) at Bald Head Island, NC, to examine past and predict future sex ratios under scenarios of warming. There were no significant temporal trends in primary sex ratio evident in recent years and estimated mean annual sex ratio was 58% female. Similarly, there were no temporal trends in phenology but earlier nesting and longer nesting seasons were correlated with warmer sea surface temperature. We modelled the effects of incremental increases in mean AT of up to 7.5°C, the maximum predicted increase under modelled scenarios, which would lead to 100% female hatchling production and lethally high incubation temperatures, causing reduction in hatchling production. Populations of turtles in more southern parts of the United States are currently highly female biased and are likely to become ultra‐biased with as little as 1°C of warming and experience extreme levels of mortality if warming exceeds 3°C. The lack of a demonstrable increase in AT in North Carolina in recent decades coupled with primary sex ratios that are not highly biased means that the male offspring from North Carolina could play an increasingly important role in the future viability of the loggerhead turtle in the Western Atlantic.