bluuebunny/crossref_metadata_2025 huggingface dataset:
Opportunism, knowledge, and the performance of franchise chains
Authors: Barthélemy Jérôme
Published: September 2008

An important feature of most franchise chains is that they simultaneously use franchised and company‐owned outlets. In this study, I show that the relationship between the resources provided to outlet managers and the financial performance of franchise chains is contingent on their governance structure. Specifically, opportunism and knowledge considerations seem to prevent chains with a large proportion of franchised outlets from fully leveraging resources such as a valuable brand name and tacit business practices. On the other hand, brand name value and business practices tacitness are not directly related to the proportion of franchised outlets in chains. Copyright © 2008 John Wiley & Sons, Ltd.
Spawned with a silver spoon? Entrepreneurial performance and innovation in the medical device industry
Authors: Chatterji Aaron K.
Published: September 2008

Entrepreneurs in high‐technology industries often have prior experience at incumbent firms, but we know little about how knowledge obtained at the prior employer impacts entrepreneurial performance. Drawing on previous work from strategy, economics, and organizational sociology, I assess the impact of industry experience on entrepreneurial performance and innovation in medical device start‐ups. I find that spawns (ventures started by former employees of incumbent firms) perform better than other new entrants. Interestingly, my findings suggest that this superior performance is not driven by technological spillovers from parent to spawn, but rather by nontechnical knowledge related to regulatory strategy and marketing. Copyright © 2008 John Wiley & Sons, Ltd.
Understanding the alliance data
Authors: Schilling Melissa A.
Published: September 2008

A considerable body of research utilizes large alliance databases (e.g., SDC, MERIT‐CATI, CORE, RECAP, and BIOSCAN) to study interorganizational relationships. Understanding the strengths and limitations of these databases is crucial for informing database selection and research design. In this study I conduct an analysis of five prominent alliance databases. Focusing on technology alliances (those formed for the purposes of joint research or cross‐technology transfer), I examine the databases' consistency of coverage and completeness, and assess whether different databases yield the same patterns in sectoral composition, temporal trends, and geographic patterns in alliance activity. I also replicate three previously published alliance studies to assess the impact of data limitations on research outcomes. The results suggest that the databases only report a fraction of formally announced alliances, which could have detrimental consequences for some types of research. However, the databases exhibit strong symmetries in patterns of sectoral composition, alliance activity over time, and geographic participation. Furthermore, the replications of previous studies yielded results that were highly similar to those obtained in the original studies. This study thus provides some reassurance that even though the databases only capture a sample of alliance activity, they may yield reliable results for many—if not all—research purposes. This information should help researchers make better‐informed decisions about their choice of database and research design. Copyright © 2008 John Wiley & Sons, Ltd.
Evaluating the recovery‐oriented approach through the systematic development of real complex applications
Authors: Magalhães João , von Staa Arndt , de Lucena Carlos José Pereira
Published: September 2008

Recovery‐oriented software is built with the perspective that hardware or software failures and operation mistakes are facts to be coped with, as they are problems that cannot be fully solved while developing real complex applications. Consequently, any software will always have a non‐zero chance of failure. Some of these failures may be caused by defects that may be removed or encapsulated. From the point of view of removing or encapsulating defects, a failure is considered to be trivial, when (i) the required effort to identify and eliminate or encapsulate the causing defect is small, (ii) the risk of making mistakes in these steps is also small and (iii) the consequences of the failure are tolerable. It is highly important to design systems in such a way that most (ideally all) of the failures are trivial. Such systems are called ‘debuggable systems’. In this study, we present the results of systematic applying techniques that focus on creating debuggable software for real embedded applications. Copyright © 2008 John Wiley & Sons, Ltd.
Maternal endothelial function and serum concentrations of placental growth factor and soluble endoglin in women with abnormal placentation
Authors: Savvidou M. D. , Noori M. , Anderson J. M. , Hingorani A. D. , Nicolaides K. H.
Published: September 2008

Objectives

To determine whether maternal serum concentrations of placental growth factor (PlGF) and soluble endoglin (sEng) are altered in women who subsequently develop pre‐eclampsia (PE) or have small‐for‐gestational‐age (SGA) infants, and whether these changes are associated with maternal endothelial dysfunction.

Methods

Maternal serum PlGF and sEng were measured in two groups of pregnant women at 23–25 weeks' gestation: Group A (n = 40), with normal uterine artery Doppler waveforms and Group B (n = 43) with abnormal Doppler. Maternal endothelial dysfunction was assessed by flow‐mediated dilatation (FMD) of the brachial artery. Comparisons between groups were performed using one‐way analysis of variance.

Results

In Group B, 16 women had normal outcome, 15 delivered SGA infants and 12 developed PE. Women who developed PE had lower levels of PlGF (154.8 ± 150.8 vs. 423.3 ± 230.5 pg/mL; P < 0.001) (data given as mean ± SD) and higher levels of sEng (8.1 (7.0–14.1) vs. 6.5 (4.9–7.9) pg/mL; P < 0.05) (data given as median (interquartile range)) than Group A. Similar were the findings in women who delivered SGA infants. In women who subsequently developed PE, there was no correlation between FMD and either PlGF or sEng.

Conclusions

Maternal serum concentrations of PlGF and sEng are altered in women who develop PE. However, these alterations do not correlate directly with maternal endothelial dysfunction. Copyright © 2008 ISUOG. Published by John Wiley & Sons, Ltd.
Realization of High Performance AR‐coatings with Dust‐ and Water‐Repellent Properties
Authors: Bruynooghe S. , Spinzig S. , Fliedner M. , HSU G.J.
Published: September 2008

Hydrophobic coatings enable the manufacture of easy‐to‐clean surfaces having dust‐ and water‐repellent properties. In this work, a hydrophobic coating is deposited as a top layer on an antireflective (AR) multilayer system to produce low reflectance optical surfaces at a normal incident angle in the visible spectrum with dust‐ and water‐repellent properties for applications in precision optics. It is shown that the hydrophobic coating can be considered, from an optical point of view, as two adjacent thin layers having specific thicknesses and densities. In fact, the hydrophobic layer is one monolayer comprising molecular chains with anchoring groups responsible for the chemical bond with the substrate material and functional groups responsible for the water‐ and oil‐repellent properties. Their optical constants are determined and included in the final coating design. High performance AR coatings having an average reflectance of 0.14% at 7° incident angle in the 400‐680nm spectral range together with a pleasing purplered reflex color are produced. Coated lenses exhibit an excellent abrasion resistance, environmental stability, resistance to cleaning agents, homogeneity and water repellence with contact angles against water higher than 110°.
From probabilistic forecasts to statistical scenarios of short‐term wind power production
Authors: Pinson Pierre , Madsen Henrik , Nielsen Henrik Aa. , Papaefthymiou George , Klöckl Bernd
Published: September 2008

Short‐term (up to 2–3 days ahead) probabilistic forecasts of wind power provide forecast users with highly valuable information on the uncertainty of expected wind generation. Whatever the type of these probabilistic forecasts, they are produced on a per horizon basis, and hence do not inform on the development of the forecast uncertainty through forecast series. However, this additional information may be paramount for a large class of time‐dependent and multistage decision‐making problems, e.g. optimal operation of combined wind‐storage systems or multiple‐market trading with different gate closures. This issue is addressed here by describing a method that permits the generation of statistical scenarios of short‐term wind generation that accounts for both the interdependence structure of prediction errors and the predictive distributions of wind power production. The method is based on the conversion of series of prediction errors to a multivariate Gaussian random variable, the interdependence structure of which can then be summarized by a unique covariance matrix. Such matrix is recursively estimated in order to accommodate long‐term variations in the prediction error characteristics. The quality and interest of the methodology are demonstrated with an application to the test case of a multi‐MW wind farm over a period of more than 2 years. Copyright © 2008 John Wiley & Sons, Ltd.
Comparison of pitching and plunging effects on the surface pressure variation of a wind turbine blade section
Authors: Soltani M. R. , Seddighi M. , Marzabadi F. Rasi
Published: September 2008

Numerous experiments were conducted on an oscillating airfoil in a subsonic wind tunnel. The experiments involved measuring the surface pressure distribution when the model oscillated in two types of motion, pitch and plunge, at three different Reynolds numbers, 0.42, 0.63 and 0.84 million, and over a range of reduced frequencies, k = 0.03–0.09. The unsteady aerodynamic loads were calculated from the surface pressure measurements, 64 ports, along the chord for both upper and lower surfaces of the model. Particular emphasis was placed on the effects of different types of motion on the unsteady pressure distribution of the airfoil at pre‐stall, near‐stall and post‐stall conditions. It was found that variations of the pressure distribution and aerodynamic loads with angle of attack were strongly sensitive to the displacement, oscillation frequency and mean angle of attack. The width of the hysteresis loop, position of the ‘figure‐8 shape’ and slope of the pressure coefficient curve are influenced by both types of motion, pitch and plunge. The main difference between plunging and pitching motions is due to the presence of the pitch rate for the pitching motion case, which was absent in the plunging case. Pitch rate had the strongest influence on pressure data in the near‐stall and post‐stall conditions. The trend of increasing the width of the hysteresis loops of lift coefficients with changing reduced frequency was different in two motions in the pre‐stall and post‐stall regions. The aerodynamic damping was greater for the pitching case than for the plunging one at higher reduced frequencies due to the existence of the pitch rate in the pitching oscillation, which was reversed at lower reduced frequencies. In the near‐stall region, at higher reduced frequency, the dynamic stall angle for the pitching oscillation increased while for the plunging one the effect was minimal. Increasing the oscillation amplitude was more effective for the plunging motion than for the pitching one. The effects of surface grit roughness on the pressure signature for both types of motion were also investigated. Applying the surface roughness near the leading edge affected the performance of the airfoil significantly. Copyright © 2008 John Wiley & Sons, Ltd.
Testing a deterministic implementation against a non-controllable non-deterministic stream X-machine
Authors: Hierons Robert M. , Ipate Florentin
Published: September 2008

A stream X-machine (SXM) is a type of extended finite state machine with an associated development approach that consists of building a system from a set of trusted components. One of the great benefits of using SXMs for the purpose of specification is the existence of test generation techniques that produce test suites that are guaranteed to determine correctness as long as certain well-defined conditions hold. One of the conditions that is traditionally assumed to hold is controllability: this insists that all paths through the SXM are feasible. This restrictive condition has recently been weakened for testing from a deterministic SXM. This paper shows how controllability can be replaced by a weaker condition when testing a deterministic system against a non-deterministic SXM. This paper therefore develops a new, more general, test generation algorithm for testing from a non-deterministic SXM.
The diagnostic value of ultrasound in cystic kidney diseases
Authors: Vester Udo , Kranz Birgitta , Hoyer Peter F.
Published: September 2008

Renal cysts in childhood can be found in a variety of diseases, which can be congenital or acquired, or renal cysts may be part of a multiorgan disease or restricted to the kidneys only. Ultrasonography is the first-line diagnostic tool and is informative in many cases. However, there is a broad spectrum in the sonographic appearance of renal cysts, and family or genetic studies, a search for extrarenal organ involvement, or additional imaging modalities may be required to make a definitive diagnosis. The aim of this article is to summarize the diagnostic potential and limitations of ultrasonography and depict typical examples of the most important cystic entities.
Fractal Nanotechnology
Authors: Cerofolini GF , Narducci D , Amato P , Romano E
Published: September 2008

Self-similar patterns are frequently observed in Nature. Their reproduction is possible on a length scale 102–105 nm with lithographic methods, but seems impossible on the nanometer length scale. It is shown that this goal may be achieved via a multiplicative variant of the multi-spacer patterning technology, in this way permitting the controlled preparation of fractal surfaces.
Populationsgenetik des humanen X-Chromosoms
Authors: Szibor R.
Published: September 2008

Die mitochondriale DNA und das Y-Chromosom (ChrY) weisen einen sehr hohen Informationsgehalt hinsichtlich der Entwicklungsgeschichte des Menschen und der verwandtschaftlichen Nähe humaner Populationen auf. Das liegt daran, dass mit Ausnahme der pseudoautosomalen Regionen des ChrY beide genomischen Kompartimente nicht rekombinieren und dass die Typisierung haploider Marker automatisch die Identifizierung von Haplotypen erlaubt. Das X-Chromosom (ChrX) nimmt hinsichtlich seines Rekombinationsverhaltens eine intermediäre Stellung zwischen den Autosomen und dem ChrY ein. Auch seine populationsgenetische Bedeutung beruht z. T. auf der leichteren Identifizierbarkeit von Haplotypen. Während ChrY und mtDNA aber jeweils nur einen einzigen Locus mit einheitlicher Entwicklungsgeschichte repräsentieren, setzt sich das ChrX aus mehreren Abschnitten zusammen, die jeweils eine eigene Historie reflektieren können. Daher erscheinen ChrX-Studien immer dann besonders sinnvoll, wenn Subpopulationen voneinander unterschieden oder regionale ethnische Strukturen erforscht werden sollen. Aus populationsgenetischer Sicht spielt die Analyse von Kopplungsungleichgewichten zwischen ChrX-Markern eine besondere Rolle, da mit ihrer Hilfe genetische Isolate und die Abstammung einzelner Gruppierungen von kleinen Gründerpopulationen nachgewiesen werden können. Populationen mit häufigen und hohen Kopplungsungleichgewichten haben eine besondere Bedeutung für die Identifizierung der Gene, deren Variation zur Ätiologie multifaktorieller Erkrankungen beiträgt.
Populationsgenetische mitochondriale DNA-Daten
Authors: Bandelt H.-J , Parson W.
Published: September 2008

Der populationsgenetische Aspekt der Nutzung mitochondrialer DNA in der Forensik und medizinischen Genetik bezieht sich implizit auf die gesamte Datengrundlage und die mtDNA-Phylogenie, von der in Hinblick auf die zu untersuchenden Fragestellungen gezielt Teile ausgesondert werden. Wir heben besonders jene Aspekte hervor, die in der Vergangenheit bei vielen Untersuchungen nicht adäquat berücksichtigt wurden.
Grundlagen der pränatalen Diagnostik
Authors: Aichinger E. , Zerres K. , Grimm T.
Published: September 2008

Pränatale Diagnostik kann heute mit unterschiedlichen Methoden, nichtinvasiv und invasiv, erfolgen. Gute humangenetische Grundkenntnisse sind erforderlich, um die Rat suchende Schwangere mit ihrem Partner umfassend zu informieren, damit von diesen auf der Grundlage des „informed consent“ alle notwendigen Entscheidungen getroffen werden können.
The 3 ‘R’s—Re-Validation, Re-Licensing and Re-Certification How Will it Affect Urologists?
Authors: Sinclair A.M. , Bridgewater B. , O'Flynn K.J. , Joyce A.D.
Published: September 2008

The publication of the Government's White Paper on re-validation and GMC proposals will have a profound effect on urologists and the way they practice. This paper looks at the components of re-validation and ‘Good Medical Practice’ and examines how clinicians, particularly urologists, may be assessed to ensure they remain on the specialist register.
Age-Specific PSA Reference Values Based on a Screening Population of British Men
Authors: Winkler M.H. , Mayer E.K. , Carter A. , Kulinskaya E. , Green J.S.A.
Published: September 2008

Objective:

Age-specific PSA reference values are recommended by the Department of Health and NICE as a referral trigger for men with abnormal PSA values. They are arbitrary values in the UK and are based on the international literature.

Patients and methods:

Data of 1970 men with benign histology from the Gwent screening study were used out of a cohort of 2063 men. The adaptive trimmed maximum likelihood method as the best way of removing outliers which do not come from a log-normal distribution was used after data transformation. The 95% percentile was used as cut-off value.

Results:

The true statistical 95% percentile for PSA in a screening population for the age groups 50–59.9 years, 60–69.9 years and 70–79.9 years are 3.2ng/ml, 5.6ng/ml and 8.1 ng/ml, respectively.

Conclusions:

These values differ from the recommended referral cut-off values by the Department of Health. The adoption of higher values for the older age groups may be a sensible policy to avoid unnecessary investigation in elder men with high PSA values due to benign disease.
What is the Role of Retrograde Ureteroscopy in the Management of Large Renal Calculi?
Authors: Forster J.A. , Moazzam M. , Lloyd S.N.
Published: September 2008

Background and purpose:

The management of large renal calculi has traditionally been with percutaneous nephrolithotomy (PCNL) or occasionally extracorporeal shock wave lithotripsy (ESWL). We present our experience of ureteroscopic treatment of large renal calculi in patients where PCNL/ESWL were contraindicated, refused or failed.

Patients and methods:

Data from 30 patients with intra-renal calculi ≥20 mm was prospectively entered onto a database and analysed. Patients were treated with rigid and flexible ureteroscopy (URS) using holmium laser or lithoclast (pneumatic) lithotripsy.

Results:

Mean stone size was 2.8cm (range 2.0–6.0cm). The most common indications were ESWL failure (40%), anatomical reasons (20%), patient choice (10%) and failed PCNL access (7%). Stone clearance (no fragments >3 mm on follow-up imaging) was observed after one URS treatment alone in 30% of patients and a further 27% with a post-operative session of ESWL. Two URS sessions alone were used in 23% of patients, with a single patient needing two URS and post-operative ESWL. Three URS sessions plus ESWL was used in 7% of patients. Three patients (10%) required PCNL. Median operative time was 60min. Complications were minimal: four patients had urinary tract infection, one failed trial without catheter, one atrial fibrillation, and one stent migration.

Conclusion:

Where PCNL is not favoured for any reason, patients with a large stone burden can be safely and effectively managed with retrograde URS, either with the intention of stone clearance or de-bulking prior to ESWL.
Specific reaction of α,β‐unsaturated carbonyl compounds such as 6‐shogaol with sulfhydryl groups in tubulin leading to microtubule damage
Authors: Ishiguro Kazuhiro , Ando Takafumi , Watanabe Osamu , Goto Hidemi
Published: September 2008

6‐Shogaol and 6‐gingerol are ginger components with similar chemical structures. However, while 6‐shogaol damages microtubules, 6‐gingerol does not. We have investigated the molecular mechanism of 6‐shogaol‐induced microtubule damage and found that the action of 6‐shogaol results from the structure of α,β‐unsaturated carbonyl compounds. α,β‐Unsaturated carbonyl compounds such as 6‐shogaol react with sulfhydryl groups of cysteine residues in tubulin, and impair tubulin polymerization. The reaction with sulfhydryl groups depends on the chain length of α,β‐unsaturated carbonyl compounds. In addition, α,β‐unsaturated carbonyl compounds are more reactive with sulfhydryl groups in tubulin than in 2‐mercaptoethanol, dithiothreitol, glutathione and papain, a cysteine protease.
Completing the family portrait of the anti‐apoptotic Bcl‐2 proteins: Crystal structure of human Bfl‐1 in complex with Bim
Authors: Herman Maria Dolores , Nyman Tomas , Welin Martin , Lehtiö Lari , Flodin Susanne , Trésaugues Lionel , Kotenyova Tetyana , Flores Alex , Nordlund Pär
Published: September 2008

Evasion of apoptosis is recognized as a characteristic of malignant growth. Anti‐apoptotic B‐cell lymphoma‐2 (Bcl‐2) family members have therefore emerged as potential therapeutic targets due to their critical role in proliferating cancer cells. Here, we present the crystal structure of Bfl‐1, the last anti‐apoptotic Bcl‐2 family member to be structurally characterized, in complex with a peptide corresponding to the BH3 region of the pro‐apoptotic protein Bim. The structure reveals distinct features at the peptide‐binding site, likely to define the binding specificity for pro‐apoptotic proteins. Superposition of the Bfl‐1:Bim complex with that of Mcl‐1:Bim reveals a significant local plasticity of hydrophobic interactions contributed by the Bim peptide, likely to be the basis for the multi specificity of Bim for anti‐apoptotic proteins.
Retracted: Isosorbide mononitrate versus alendronate for postmenopausal osteoporosis
Authors: Nabhan Ashraf F. , Rabie Noha H.
Published: September 2008

Objective

To compare the effectiveness, safety, and affordability of isosorbide mononitrate with alendronate for postmenopausal osteoporosis.

Methods

A randomized controlled trial of 60 postmenopausal women with osteoporosis. Participants were randomly assigned to receive either 20 mg daily of isosorbide mononitrate or 70 mg weekly of alendronate for 12 months. Bone mineral density (BMD) was measured using dual X‐ray absorptiometry (DXA) at baseline and after 12 months.

Results

Both groups showed significant improvement in BMD. Isosorbide mononitrate yielded a comparable effect to alendronate for BMD and T‐score at the end of the follow‐up period. For BMD and T score the mean differences between the 2 groups were – 0.005 (95% CI, – 0.02 to 0.03) and 0.31 (95% CI, – 0.03 to 0.64), respectively. A 10.8% and 12.1% change in BMD after 12 months was seen for isosorbide mononitrate and alendronate, respectively.

Conclusion

Isosorbide mononitrate is comparable to alendronate. Nitric oxide donors may be an effective and affordable therapy to improve bone mineral density.
Bilateral uterine artery ligation via minilaparotomy for heavy menstrual bleeding
Authors: Hassanin Ibrahim M.A. , Shahin Ahmed Y. , Abdel‐Hafeez Ahmed T. , Salem Hosam T. , El‐Nashar Sherif A.
Published: September 2008

Objective

To assess the safety and short‐term efficacy of bilateral uterine artery ligation (UAL) via minilaparotomy for the management of heavy menstrual bleeding (HMB).

Methods

A prospective study of 30 women with HMB who underwent UAL. The primary outcome was cumulative treatment failure 12 months after the procedure. Treatment failure was defined as the need for hysterectomy during the follow‐up period.

Results

At 12 months, 6 women had undergone hysterectomy for bleeding, for a cumulative failure rate of 20% (95% CI, 9%–38%). The number of bleeding days was significantly reduced by 11.9 ± 1.5 days (P < 0.001) and hemoglobin level significantly increased by 1.3 ± 0.15 g/dL (P < 0.001). Of the 30 women, 24 (80%) were satisfied with the results. No major complications were reported during the procedure or median follow‐up period of 13.2 months.

Conclusion

Bilateral UAL is a safe and effective minimally invasive procedure that can provide an alternative treatment for HMB.
Paleoclimate reconstruction in the Levant region from the geochemistry of a Holocene stalagmite from the Jeita cave, Lebanon
Authors: Verheyden Sophie , Nader Fadi H. , Cheng Hai J. , Edwards Lawrence R. , Swennen Rudy
Published: September 2008

Dated oxygen and carbon isotopic profiles from a Holocene stalagmite (11.9–1.1 ka) from the Jeita cave, Lebanon, are compared to variations in crystallographic habit, stalagmite diameter and growth rate. The profiles show generally high δ18O and δ13C values during the late-glacial period, low values during the early Holocene, and again high values after 5.8 ka. On the basis of the good correlation between the morphological and crystallographic aspect of the stalagmite and its isotopic records, as well as the isotopic response of speleothems from central and northern Israel, we relate high δ18O and δ13C values to drier conditions. Between 6.5 and 5.8 ka an increase in isotopic values, a decrease in growth rate and stalagmite diameter suggest a transition from wet conditions in the early Holocene towards drier conditions in the mid-Holocene. The transition occurred in two steps, first a progressive change to drier conditions started at 6.5 ka but was interrupted by a short (∼ 100 years) return to wetter conditions, followed by an equally rapid (< 200 years) change to drier conditions.
Calculating long‐term global air‐sea flux of carbon dioxide using scatterometer, passive microwave, and model reanalysis wind data
Authors: Fangohr Susanne , Woolf David K. , Jeffery Christopher D. , Robinson Ian S.
Published: September 2008

Global air‐sea flux of carbon dioxide (CO2) is calculated from wind data acquired by the satellite scatterometer QuikSCAT, the passive microwave radiometer AMSR‐E, and the model reanalysis ERA‐40 using four of the most commonly used wind speed dependent parameterizations of gas transfer velocity. Assuming QuikSCAT as reference, the results are compared to obtain an estimate of that relative uncertainty in the flux calculations which results solely from the origin of the input wind data. We illustrate the discrepancies between these data sets and quantify the uncertainty in the computed air‐sea CO2 flux that arises from data processing such as temporal and spatial averaging using AMSR‐E as an example data set. The impact of temporal variability of wind speed is shown to be significantly greater than that of spatial variability. However, simple parameterizations of temporal variability are found to be sensor‐specific and cannot be applied in a straightforward way to data sets with lower temporal resolutions from other sensors. We show a simple methodology to correct monthly mean data in such a way that seasonally and zonally varying parameterizations of temporal variability derived from QuikSCAT data can be applied to data from AMSR‐E and ERA‐40. This allows us to produce a global 44‐year time series of gas transfer velocity and to present a more coherent estimate of air‐sea transfer of carbon dioxide from the three most commonly available types of wind data.
A criterion for identifying Asian dust events based on Al concentration data collected from northern Taiwan between 2002 and early 2007
Authors: Hsu Shih‐Chieh , Liu Shaw Chen , Huang Yi‐Tang , Lung Shih‐Chun Candice , Tsai Fujung , Tu Jien‐Yi , Kao Shuh‐Ji
Published: September 2008

We attempted to identify Asian dust (AD) events between February 2002 and February 2007 in northern Taiwan using aerosol Al measurements. We subsequently used the results to propose a criterion for defining AD events. A total of 30 AD events were detected based on Al spiking concentrations, and these occurred frequently in 2002 and 2006. The dust plumes that were identified occurred between November and April, which were concentrated in February, March, and April. There were 35 dusty days, which accounted for 1.89% of the whole study period, and for 3.75% when considering only November through April. The seasonality of atmospheric Al is quite evident, reaching a maximum in spring and winter and a minimum in summer. This pattern is related to the long‐range transport of AD in the northeasterly monsoon and the cease of AD contributions, the efficient removal by heavy rain, and effective mixing in summer. According to air‐mass trajectory analysis, the primary dust regions are located in and around the Gobi Desert and Loess Plateau. The geometric mean concentration of the data set excluding the AD cases is 502 ng m−3 with a geometric standard deviation (GSD) of 2.8. On the basis of our success in identifying the major AD events, the “geometric mean ×2 GSD” (i.e., 2800 ng m−3 in our study area) is proposed as a straightforward criterion to define the significant AD event. As such, the statistic‐based criterion could be applicable for other areas.
A methodology for calculating the spatial distribution of the area‐slope equation and the hypsometric integral within a catchment
Authors: Cohen Sagy , Willgoose Garry , Hancock Greg
Published: September 2008

The area‐slope relationship and the hypsometric curve are well known catchment descriptors. The main shortcoming of traditional area‐slope and hypsometry extraction methods is their limited ability to represent heterogeneity within the catchment. Here we present a new methodology for explicit calculation of the spatial distribution, at a pixel scale within a catchment, of the area‐slope parameters and the hypsometric integral. This method allows us to create a quantitative representation of the area‐slope equation and the hypsometric integral which can potentially be used in a variety of geomorphologic applications. The results show that the spatial distribution of both the area‐slope equation and the hypsometric integral are noisy at the pixel scale. In order to reduce the noise three averaging techniques were examined. Subcatchment‐scale averaging was found to be the best at identifying the spatial distribution of the area‐slope equation and hypsometric integral. At the subcatchment scale the spatial distribution of the area‐slope equation and the hypsometric integral approximated the spatial distribution of soil morphological and geological units of the Goulburn River catchment in eastern Australia. The spatially distributed area‐slope results were tested using manually extracted subcatchment average area‐slope values and found to be well correlated. The spatially distributed hypsometric integral was also well correlated with landform concavity and convergence. The subcatchment‐scale averaging of the spatially distributed area‐slope equation and hypsometric integral is shown to be a promising tool for producing spatially distributed data. The techniques are demonstrated on a catchment that has marked spatial variation in soils and geology. The results show that the spatially explicit maps can potentially identify the spatial extent of these soil types and geological features and agrees well with existing soil maps.
A Wiener‐Hopf analysis of the parallel plate waveguide with finite length impedance loading
Authors: Tayyar İsmail H. , Büyükaksoy Alinur , Işıkyer Ayşegül
Published: September 2008

In the present work a rigorous Wiener‐Hopf approach is used to investigate the band‐stop filter characteristics of a parallel plate waveguide with finite length impedance loading. The representation of the solution to the boundary‐value problem in terms of Fourier integrals leads to two simultaneous modified Wiener‐Hopf equations which are uncoupled by using the pole removal technique. The solution involves four infinite sets of unknown coefficients satisfying four infinite systems of linear algebraic equations. These systems are solved numerically and some graphical results showing the influence of the waveguide spacing, surface impedances and the length of the impedance loading on the reflection coefficient are presented.
Highly extended terrains, lateral segmentation of the substratum, and basin development: The middle‐late Miocene Radicondoli Basin (inner northern Apennines, Italy)
Authors: Brogi Andrea , Liotta Domenico
Published: September 2008

This paper deals with the evolution of sedimentary basins not delimited by normal faults, with a substratum characterized by an upward concave shape and with infilling sediments synclinally deformed. We describe the middle‐late Miocene Radicondoli Basin, representing an example of such bowl‐shaped basins. Its tectonic origin is controversial, being related both to compression and extension; these opposite interpretations bear significant consequences on the geodynamic context in which the inner northern Apennines developed during the middle‐late Miocene. The results of our structural studies, carried out in the substratum and infilling sediments, indicate that the Radicondoli Basin is an example of a hanging wall basin developed in an extensional setting. Extensional tectonics determined the lateral segmentation of the substratum competent levels (i.e., Tuscan Nappe and Verrucano Group) and the consequent collapse of overlying less competent levels (i.e., the Ligurian units) with the formation of a bowl‐shaped tectonic depression. Here, the syntectonic sediments (Serravallian–late Messinian) are deformed in a large syncline, characterized by minor gravity‐driven folds, with vergences toward the depocenter and traces of their axial planes parallel to the basin margins. This paper highlights the role of the competence contrast during the postcollisional tectonic evolution and the influence of substratum lateral segmentation for the accommodation of syntectonic sediments.
River sediment load and concentration responses to changes in hydrology and catchment management in the Loess Plateau region of China
Authors: Rustomji P. , Zhang X. P. , Hairsine P. B. , Zhang L. , Zhao J.
Published: September 2008

To reduce the sediment load of China's Yellow River, soil conservation measures have been progressively implemented across the Loess Plateau region since the 1950s. The effectiveness of these soil conservation measures (which were also coincident with reduced rainfall and streamflow) in controlling sediment movement remains to be ascertained. Here the association between sediment movement, hydrological variability, and the implementation of soil conservation measures is examined for the Coarse Sandy Hilly Catchments region of the Yellow River basin. The hypothesis that the soil conservation measures have reduced suspended sediment yields beyond that associated with rainfall reductions alone, principally by reducing sediment concentration, is examined. Annual sediment yield decreased significantly over time in all subcatchments, and the timing of the change (between 1971 and 1985) was consistent with the timing of change in streamflow. Annual mean sediment concentration in 7 of the 11 catchments exhibited a statistically significant decreasing trend over time, indicating that soil conservation practices reduced the mobilization of sediment in most areas, typically accounting for ∼75% of the observed reductions in annual sediment yield. Lesser reductions in area‐specific sediment yield at larger catchment areas after the soil conservation measures were emplaced suggests that larger rivers may be reeroding stored sediment. As these sediment stores are likely to be relatively large given the high historic yields, relatively high area‐specific sediment yields may persist at larger catchment areas even with improvements to sediment management in smaller tributaries.
Quantitative comparison of canopy conductance models using a Bayesian approach
Authors: Samanta S. , Clayton M. K. , Mackay D. S. , Kruger E. L. , Ewers B. E.
Published: September 2008

A quantitative model comparison methodology based on deviance information criterion, a Bayesian measure of the trade‐off between model complexity and goodness of fit, is developed and demonstrated by comparing semiempirical transpiration models. This methodology accounts for parameter and prediction uncertainties associated with such models and facilitates objective selection of the simplest model, out of available alternatives, which does not significantly compromise the ability to accurately model observations. We use this methodology to compare various Jarvis canopy conductance model configurations, embedded within a larger transpiration model, against canopy transpiration measured by sap flux. The results indicate that descriptions of the dependence of stomatal conductance on vapor pressure deficit, photosynthetic radiation, and temperature, as well as the gradual variation in canopy conductance through the season are essential in the transpiration model. Use of soil moisture was moderately significant, but only when used with a hyperbolic vapor pressure deficit relationship. Subtle differences in model quality could be clearly associated with small structural changes through the use of this methodology. The results also indicate that increments in model complexity are not always accompanied by improvements in model quality and that such improvements are conditional on model structure. Possible application of this methodology to compare complex semiempirical models of natural systems in general is also discussed.
Intra‐annual variability of the low‐latitude ionosphere due to nonmigrating tides
Authors: Pedatella N. M. , Forbes J. M. , Oberheide J.
Published: September 2008

In‐situ plasma density measurements from the CHAMP satellite between about 350–420 km altitude are used to delineate intra‐annual variations in the longitudinal structure of the F‐region ionosphere. It is shown that the longitude structures during mid‐day local times are dominated by the space‐based longitudinal wavenumbers ks = 2, 4 and 3 in January, July and December, respectively. These conform to the same dominating ks‐values characterizing solar thermal tide zonal winds in the dynamo region, namely the westward‐propagating semidiurnal tide with planetary‐fixed zonal wavenumber s = 4 (SW4), and the eastward‐propagating diurnal tides with s = −3 (DE3) and s = −2 (DE2), respectively. DE3 is the dominating tide during the other months. The results presented indicate that nonmigrating tides other than DE3 may significantly impact the longitudinal structure of the low‐latitude ionosphere during certain months.
Surface temperature cooling trends and negative radiative forcing due to land use change toward greenhouse farming in southeastern Spain
Authors: Campra Pablo , Garcia Monica , Canton Yolanda , Palacios‐Orueta Alicia
Published: September 2008

Greenhouse horticulture has experienced in recent decades a dramatic spatial expansion in the semiarid province of Almeria, in southeastern (SE) Spain, reaching a continuous area of 26,000 ha in 2007, the widest greenhouse area in the world. A significant surface air temperature trend of −0.3°C decade−1 in this area during the period 1983–2006 is first time reported here. This local cooling trend shows no correlation with Spanish regional and global warming trends. Radiative forcing (RF) is widely used to assess and compare the climate change mechanisms. Surface shortwave RF (SWRF) caused through clearing of pasture land for greenhouse farming development in this area is estimated here. We present the first empirical evidences to support the working hypothesis of the development of a localized forcing created by surface albedo change to explain the differences in temperature trends among stations either inside or far from this agricultural land. SWRF was estimated from satellite‐retrieved surface albedo data and calculated shortwave outgoing fluxes associated with either uses of land under typical incoming solar radiation. Outgoing fluxes were calculated from Moderate Resolution Imaging Spectroradiometer (MODIS) surface reflectance data. A difference in mean annual surface albedo of +0.09 was measured comparing greenhouses surface to a typical pasture land. Strong negative forcing associated with land use change was estimated all year round, ranging from −5.0 W m−2 to −34.8 W m−2, with a mean annual value of −19.8 W m−2. According to our data of SWRF and local temperatures trends, recent development of greenhouse horticulture in this area may have masked local warming signals associated to greenhouse gases increase.
A latitudinal survey of CO, OCS, H2O, and SO2 in the lower atmosphere of Venus: Spectroscopic studies using VIRTIS‐H
Authors: Marcq E. , Bézard B. , Drossart P. , Piccioni G. , Reess J. M. , Henry F.
Published: September 2008

The high‐resolution channel (R ≃ 2000) of the Visible and Infrared Thermal Imaging Spectrometer (VIRTIS) instrument (VIRTIS‐H) aboard Venus Express has provided numerous spectra of the nightside infrared thermal emission in the 2.3‐μm window. Mixing ratios of various minor species in the 30–40 km range could therefore be inferred using this spectral window at higher latitudes accessible to the spacecraft but which cannot be observed from Earth. The previously known enhancement in carbon monoxide (CO) toward high latitudes is confirmed and extended up to 60° with a mixing ratio varying from 24 ± 3 to 31 ± 2 ppmv at 36 km. Measurements of carbonyl sulfide (OCS) also agree with the previously suspected latitudinal variations that are anticorrelated with those of CO, ranging between 2.5 ± 1 and 4 ± 1 ppmv at 33 km. New constraints were also derived on the mean abundance of water vapor (H2O, 31 ± 2 ppmv) and sulfur dioxide (SO2, 130 ± 50 ppmv) in the probed altitude range. CO and OCS variations are interpreted as caused by large‐scale vertical motions, an explanation under current testing by various chemical and dynamical modeling. In such a case, these variations may help constrain the chemical time scale of those species in the lower troposphere.
Impact fracturing and structural modification of sedimentary rocks at Meteor Crater, Arizona
Authors: Kumar P. Senthil , Kring David A.
Published: September 2008

Meteor Crater provides a rare opportunity to study impact deformation of sedimentary target rocks and isolate those features from preexisting tectonic deformation and impact‐generated reactivation of preexisting tectonic features. This study reports over 2500 new measurements of orientations of bedding, faults, and fractures in crater walls and in surrounding bedrock. Target rocks are characterized by horizontal bedding planes that are cut by at least three prominent sets of preimpact tectonic fracture systems. The crater rim is also cut by three distinct groups of fractures: radial, concentric, and conical fractures. When the crater rim is restored to preimpact condition, the radial and concentric fractures resemble preimpact fracture populations, indicating that crater wall deformation and rim uplift were partly accommodated by activation of preexisting fractures. In contrast, the conical fractures are dissimilar to the preimpact fractures and apparently formed as a direct result of impact deformation. Some of the preimpact fractures were transformed into tear faults during the impact event, and motion along those faults appears to have controlled the geometry of the impact deformational features. The crater rim is, thus, square in plan view rather than circular. Faults occurring in the crater diagonals are prominent ones, allowing greater vertical displacement. The deformation pattern of Meteor Crater is different from that at Lonar Crater, which was excavated in basalt with fewer preimpact fractures. The differences between deformation at Meteor Crater and Lonar Crater may reflect the same disparities seen in simple craters produced in different target lithologies on Mars and other planetary surfaces.
Changes in Ca, Fe, Mg, Mo, Na, and S content in a Mediterranean shrubland under warming and drought
Authors: Sardans J. , Peñuelas J. , Prieto P. , Estiarte M.
Published: September 2008

In an evergreen Mediterranean shrubland we conducted a 6‐year field experiment simulating the warming and drought projected by general circulation models and ecophysiological models for the next decades: 20% reduction of soil moisture and 1°C of temperature increase. We tested whether warming and drought have effects on Ca, Fe, Mg, Mo, Na and S availability, concentrations and accumulation patterns in the three dominant plant species and in soil. Warming increased concentrations of Ca and Mo in leaves inErica multiflora(42% and 65%, respectively) and inDorycnium pentaphyllum(38% and 60%, respectively). Warming increased Mo accumulation in leaves and aboveground biomass inGlobularia alypum(0.07 and 0.40 g ha−1) and inE. multiflora(0.12 and 0.4 g ha−1), and increased Fe accumulation in stem biomass ofG. alypum(600 g ha−1), increasing the capacity to retain these nutrients in the ecosystem. The increase of Fe and Mo capture capacity under warming conditions was greater inG. alypumthan inE. multifloracoinciding with its greater increases in photosynthetic capacity. Warming decreased soil total‐Fe concentration by 24% and increased Mg accumulation in soil exchange complex by 19%. Drought increased Na leaf and stem concentrations (93% and 50%, respectively) and accumulation in leaf and aboveground biomass (780 and 800 g ha−1, respectively) inG. alypum, allowing an increase of osmotic pressure which helps to prevent water losses and is related to its capacity to resist drought. Drought reduced S leaf and Mg leaf‐litter concentrations ofG. alypumand increased them in leaves ofE. multifloraand also increased Mo and Na concentrations in leaves ofD. pentaphyllum. Drought increased Fe soil solubility by 65%. The results indicate different effects of climate change on nutrient status in the ecosystem depending on whether the main change is warming or drought. The changes in concentration and biomass accumulation were different depending on the nutrient and the species, changing the stoichiometry among these nutrients and modifying the nutritional quality of plant tissues.