bluuebunny/crossref_metadata_2025 huggingface dataset:
Evidence of gas heating by the central AGN in MKW 3s
Authors: Giacintucci S. , Mazzotta P. , Brunetti G. , Venturi T. , Bardelli S.
Published: May 2006

We present the results of radio observations of the galaxy cluster MKW 3s carried out at 1.28 GHz and 610 MHz with the Giant Metrewave Radio Telescope (GMRT). The Chandra observations of MKW 3s revealed that this cluster is characterized by a complex X‐ray structure hosting both a X‐ray .lament and a X‐ray cavity. The temperature structure of the cluster core is even more complex, with the presence of extended regions of gas heated above the radially averaged gas temperature at any radius. The magnetic field derived from the radio observations is ∼ 2 μG and provides radiative ages of the order of ∼ 2 × 108 yrs. Thanks to this estimate of the magnetic field strength and the comparison between the radio structure and the Chandra data, we found clear evidence for a close connection between the radio activity of the central AGN and the heated gas regions in this cluster. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Magnetic turbulence in cool cores of galaxy clusters
Authors: Vogt C. , Enßlin T. A.
Published: May 2006

The analysis of Faraday rotation measurements (RM) gives insight into the properties of cluster magnetic fields. Recently, Kolmogorov‐like magnetic turbulence was reported for the cool core of the Hydra A galaxy cluster which was derived using a maximum likelihood analysis of an RM map of this cluster (Vogt & Enßlin 2005). Here, we present our understanding of this power spectrum by kinetic energy injection through active galaxies which drive a turbulent non‐helical magnetic dynamo. We develop an analytical model of the turbulence in cool cores and show that it fits well to Faraday rotation measurements for a number of cool core clusters. Moreover, our model allows predictions for magnetic fields in clusters in which the appropriate observational information is still missing, and allows predictions for yet unobserved quantities like the hydrodynamical turbulence velocity and characteristic length scale, and suggests some level of magnetic intermittency and large‐scale hydrodynamic viscosity. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Fast growth of magnetic fields in galaxy clusters: a self‐accelerating dynamo
Authors: Schekochihin A. A. , Cowley S. C.
Published: May 2006

We propose a model of magnetic‐field growth in galaxy clusters whereby the field is ampli.fied by a factor of about 108 over a cosmologically short time of ∼ 108 yr. Our model is based on the idea that the viscosity of the intracluster medium during the field‐amplification epoch is determined not by particle collisions but by plasma microinstabilities: these give rise to small‐scale .uctuations, which scatter particles, increasing their effective collision rate and, therefore, the effective Reynolds number. This gives rise to a bootstrap effect as the growth of the field triggers the instabilities which increase the Reynolds number which, in turn, accelerates the growth of the field. The growth is explosive and the result is that the observed field strength is reached over a fraction of the cluster lifetime independent of the exact strength of the seed field (which only needs to be above ∼ 10–15 G to trigger the explosive growth). (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
MHD simulations of plasma heating in clusters of galaxies
Authors: Asai N. , Fukuda N. , Matsumoto R.
Published: May 2006

We present the results of 2‐D magnetohydrodynamic (MHD) simulations of the plasma heating in clusters of galaxies. Both radiative cooling and anisotropic heat conduction are included. Magnetic turbulence is excited by the motion of gravitating clumps of the dark matter. These simulations enable us to study the thermal stability of a cluster core subjecting to turbulent magnetic fields.We found that moving clumps create hot regions ahead of them and that hot and cool plasmas coexist because magnetic fields suppress the heat conduction. Numerical results indicate that heat conduction from the hot region suspends the decrease of the temperature in the core for more than 1 Gyr. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Theoretical approaches to particle propagation and acceleration in turbulent intergalactic medium
Authors: Lazarian A.
Published: May 2006

Intercluster medium is expected to be turbulent with turbulence being superAlfvenic at large scales. Magnetic fields substantially modify the turbulent cascade when the turbulence reaches the scales at which the fluctuation velocity gets less than the Alfven velocity. At those scales it is possible to consider three cascades, of fast, slow and Alfven modes with little energy exchange between them. As Alfvenic and slow modes are anisotropic they marginally scatter and accelerate cosmic rays, while fast modes dominate the processes. However, in the presence of cosmic rays the turbulence is modified as cosmic rays transfer the energy of compressible motions (i.e. slow and fast modes) from large scales to the scale of cosmic ray Larmor radius. This results in generation of a new small‐scale Alfvenic component which is not a part of the ordinary MHD cascade. This component does scatter and accelerate cosmic rays. In addition, magnetic reconnection in turbulent medium accelerates cosmic rays. The complexity of the intracluster turbulence calls for observational studies. A new technique Velocity Coordinate Spectrum (VCS) is particularly promising for studies of velocity fluctuations with a new generation of X‐ray observatories. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Future magnetic field studies using the Planck surveyor experiment
Authors: Enßlin T. A. , Waelkens A. , Vogt C. , Schekochihin A. A.
Published: May 2006

The Planck mission will permit measurements of the polarization of the cosmic microwave background and of polarized foregrounds such as our own Galaxy with an unprecedented combination of accuracy and completeness. This will provide information on cosmological and galactic magnetic fields. The latter can be studied in detail via nearly Faraday‐rotation free synchrotron and polarized dust emission. Methods are discussed to extract physically relevant information on the magnetic turbulence from Planck data and other measurements. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Management of intrahepatic recurrence after curative treatment of colorectal liver metastases
Authors: Yan T D , Lian K Q , Chang D , Morris D L
Published: May 2006

Background

Management of intrahepatic recurrence after complete surgical treatment for colorectal liver metastases is not well defined. The aim of this study was to analyse the survival results of patients who had repeat liver resection for intrahepatic recurrence and to evaluate prognostic indicators for survival.

Methods

Between 1991 and 2005, 55 patients had repeat liver resection for isolated intrahepatic recurrence. The long-term survival results were assessed. Univariable and multivariable analyses were used to identify prognostic indicators for survival after repeat hepatectomy.

Results

The median survival was 53 (range 2–97) months and the 5-year survival rate was 49 per cent. In univariable analysis, size of largest initial liver metastasis, margin of initial liver surgery, carcinoembryonic antigen (CEA) level before and after initial liver surgery, liver disease-free survival, margin of repeat liver surgery, operation type of repeat surgery and CEA level before and after repeat surgery were significant prognostic factors. In multivariable analysis, largest initial liver metastasis 4 cm or less and CEA level 5 ng/ml or less after repeat liver surgery were independently associated with improved survival.

Conclusion

Repeat hepatectomy can achieve an acceptable survival in selected patients with isolated intrahepatic recurrence.
Psychopathy and malingering of psychiatric disorder in criminal defendants
Authors: Kucharski L. Thomas , Duncan Scott , Egan Shannon S. , Falkenbach Diana M.
Published: May 2006

Because the use of deception is an important clinical characteristic of psychopathy, there is intuitive appeal to the idea that psychopathy and malingering are associated. There is, however, very little research showing that psychopaths are more likely to malinger. We classified a sample of criminal defendants as high, moderate, or low in psychopathy, based on PCL‐R scores, and compared their scores on indices typically used to detect malingering on the MMPI‐2, the PAI and the SIRS. The high psychopathy group scored significantly higher on the MMPI‐2 F and F‐K; the PAI NIM, and the SIRS, but not the MMPI‐2 Fb, F(p), or the PAI RDF or Mal, lending some support for the DSM‐IV recommendation that malingering should be considered whenever there is a diagnosis of antisocial personality disorder. Logistic regression analysis (LGA) revealed that Factor I but not Factor II of the PCL‐R significantly discriminated malingerers from nonmalingerers with 75% correct classification. However, receiver operating characteristic (ROC) analysis revealed that psychopathy ratings had poor sensitivity and specificity in the detection of malingering. Calculation of the percentages of those exceeding accepted cut‐offs on each of the malingering measures revealed that a high percentage of severe psychopaths did not attempt to feign psychiatric disorder. The results suggest that psychopathy is not a clinically useful indictor of malingering. The results are discussed in terms of confirmatory bias and the impact such a bias could have on the evaluation of criminal defendants. Copyright © 2006 John Wiley & Sons, Ltd.
Vexatious litigants and unusually persistent complainants and petitioners: from querulous paranoia to querulous behaviour
Authors: Mullen Paul E. , Lester Grant
Published: May 2006

Querulous paranoia was once of considerable clinical and academic interest in psychiatry. Over the last 40 years, however, it has virtually disappeared from the professional landscape. This decline occurred at the very time that a proliferation of complaint organizations and agencies of accountability were drawing more and more people into asserting their individual rights through the pursuit of claims and grievances. Querulous behaviour, as a result, far from declining, is on the increase, bringing with it suffering for the querulous and disruption to the organizations through which they seek their vision of justice.

This article examines querulous behaviour in the vexatious litigant and in abnormally persistent complainants and petitioners. The phenomenological and nosological issues are outlined and the risks of the emergence of threatening and violent behaviour is emphasized. Threats should not be ignored, for a variety of reasons. Approaches to managing querulous behaviour in the courts and the complaint organizations are discussed, together with the utility of individual therapy. Querulous behaviour should once more take its place among the legitimate concerns of mental health professionals. Those caught up in a querulous pursuit of their notion of justice are amenable to management that can ameliorate their suffering and reduce the disruption they create. Copyright © 2006 John Wiley & Sons, Ltd.
Metal Nitrosyl Reactivity: Acetonitrile‐Promoted Insertion of an Alkylidene into a Nitrosyl Ligand with Fission of the NO Bond
Authors: Frech C. M. , Blacque O. , Schmalle H. W. , Berke H.
Published: May 2006

Treatment of the complexes [Re(NO)2(PR3)2][BArF4] (R = Cy, 1 a; R = iPr, 1 b) with phenyldiazomethane gave the cationic benzylidene species [Re{CH(C6H5)}(NO)2(PR3)2][BArF4] (2 a and 2 b) in good yields. Upon reaction of 2 a and 2 b with acetonitrile, the consecutive formation of [Re(NCCH3)(NCPh)(NO)(OC(CH3)NH)(PR3)][BArF4] (3 a and 3 b) and [Re(NCCH3)(OC{CH3}NH{C6H5})(NO)(PR3)2][BArF4] (4 a and 4 b) was observed. The proposed reaction sequence involves the coupling of coordinated NO, carbene and acetonitrile molecules to yield the (1Z)‐N‐[imino(phenyl)methyl]ethanimidate ligand. The coupling of the nitrosyl and the benzylidene is anticipated to occur first, forming an oximate species. The subsequent acetonitrile addition can be envisaged as a heteroene reaction of the oximate and the acetonitrile ligand yielding 3 a and 3 b, which in turn can cyclise and undergo a prototropic shift initiated by an internal attack of the ethaneimidate ligand on the benzonitrile moiety to afford 4 a and 4 b.
Cover Picture: Ligand‐Template Directed Assembly: An Efficient Approach for the Supramolecular Encapsulation of Transition‐Metal Catalysts (Chem. Eur. J. 16/2006)
Authors: Kleij Arjan W. , Reek Joost N. H.
Published: May 2006

Encapsulated catalysts are discussed in the Concept article by J. N. H. Reek and A. W. Kleij on p. 4218 ff. The authors show how template ligands can be used to form assemblies in which transition‐metal catalysts are encapsulated. These novel supramolecular catalysts are not only aesthetically attractive but show improved activity and selectivities compared with their non‐encapsulated analogues.
Regioselective Ring‐opening Reaction of 1,2‐Epoxides with Arylselenol under Solvent‐free Conditions and Application to the Synthesis of 1,3‐Oxazolidin‐2‐ones
Authors: Yang Ming‐Hua , Yuan Chao‐Ying , Pan Yi , Zhu Cheng‐Jian
Published: May 2006

Regioselective ring‐opening reactions of 1,2‐epoxides with ArSeH catalyzed by Ti(OiPr)4 under solvent‐free conditions were investigated. A variety of β‐hydroxyselenides were obtained in excellent yields of 90%–97% and regioselectivities by a simple, atom economic and environment‐friendly procedure. Several N‐tosyl‐1,3‐oxazolidin‐ 2‐ones were prepared starting from the corresponding 1,2‐epoxides and ArSeH by a one‐pot three‐step procedure.
Synthesis and Crystal Structure of the Binuclear Complex [Pr2(C10H8N2O4)2(C10H9N2O4)2(H2O)4]·3H2O·C6H6
Authors: Wu Wang‐Ting , Chen Feng‐Ying , He Shui‐Yang , Hu Huai‐Ming , Yang Meng‐Lin , Wang Yao‐Yu
Published: May 2006

The binuclear praseodymium(III) complex with N‐(1‐carboxyethylidene)‐salicylhydrazide (C10H10N2O4, H2L) was prepared in H2O‐C2H5OH mixed solution, and the crystal structure of [Pr2L2(HL)2(H2O)4]·3H2O·C6H6 was determined by X‐ray single crystal diffraction. The crystal complex crystallizes in the triclinic system with space group P‐1, and in the structure each Pr atom is 9‐coordinated by carboxyl O and acyl O and azomethine N atoms of two tridentate ligands to form two stable five‐membered rings sharing one side in keto‐mode and two water molecules. The coordination polyhedron around Pr3+ was described as a monocapped square antiprism geometry. In an individual molecule, four tridentate ligands were coordinated by two negative univalent (HL) and two bivalent forms (L) respectively. Two negative univalent ligands were coordinated via μ2‐bridging mode.
Epsilon aminocaproic acid reduces transfusion requirements in patients with thrombocytopenic hemorrhage
Authors: Kalmadi Sujith , Tiu Ramon , Lowe Christopher , Jin Tao , Kalaycio Matt
Published: May 2006

BACKGROUND

Epsilon aminocaproic acid (EACA) is an antifibrinolytic drug that has been used to control hemorrhage by stabilizing the thrombus. It has been used in thrombocytopenic patients largely on an empiric basis.

METHODS

Concerns regarding side effects have limited the use of this drug. The authors reviewed their experience with EACA at the Cleveland Clinic Foundation from 1997 to 2003.

RESULTS

Of 77 patients with thrombocytopenic hemorrhage, 51 (66%) patients achieved a complete response and 13 (17%) patients achieved a partial response, resulting in a decrease in platelet and red blood cell transfusions. Adverse effects were manageable in this set of patients with severe underlying disease.

CONCLUSIONS

Based on this experience, EACA may be a valuable adjunctive therapy in the treatment of patients with thrombocytopenic hemorrhage. Cancer 2006. © 2006 American Cancer Society.
Brief cognitive‐behavioral audiotape interventions for cancer‐related pain
Authors: Anderson Karen O. , Cohen Marlene Z. , Mendoza Tito R. , Guo Hong , Harle Margaret T. , Cleeland Charles S.
Published: May 2006

BACKGROUND

Few studies have evaluated cognitive‐behavioral interventions as an adjunct treatment for chronic cancer‐related pain. A randomized clinical trial was performed evaluating the efficacy of 3 brief cognitive‐behavioral techniques: relaxation, distraction, and positive mood interventions.

METHODS

Fifty‐seven patients with chronic cancer‐related pain taking opioid medications were randomly assigned to either the relaxation, distraction, positive mood, or waiting‐list control group. The patients in the 3 intervention groups received audiotapes of the cognitive‐behavioral technique and were asked to practice regularly at home. The tapes were supplemented with written instructions and follow‐up telephone calls.

RESULTS

Patients in the relaxation and distraction groups reported significantly reduced pain intensity immediately after listening to the tapes. The pain reduction was not maintained, however. At the 2‐week follow‐up assessment, no significant differences in pain intensity or interference were found among the treatment groups. The groups also did not differ with regard to secondary outcome measures assessing quality of life, mood, self‐efficacy, and other symptoms. The results of qualitative interviews indicated that patients often had difficulty focusing on the audiotapes and preferred their own methods of pain reduction.

CONCLUSIONS

Brief relaxation and distraction audiotape interventions produced immediate pain reductions but not longer‐term pain relief. Additional research with a more individualized intervention is needed to evaluate cognitive‐behavioral interventions for cancer pain control. Cancer 2006. © 2006 American Cancer Society.
The risk of secondary malignancies over 30 years after the treatment of non‐Hodgkin lymphoma
Authors: Tward Jonathan D. , Wendland Merideth M. M. , Shrieve Dennis C. , Szabo Aniko , Gaffney David K.
Published: May 2006

BACKGROUND

Survivors of non‐Hodgkin lymphoma (NHL) are at increased risk for developing secondary malignancies. For the current study, the authors quantitated this risk in a group of NHL survivors over 30 years of follow‐up.

METHODS

Standardized incidence ratios (observed‐to‐expected [O/E] ratio) and absolute excess risk of secondary malignancies were assessed in 77,876 patients who were diagnosed with NHL between 1973 and 2001 from centers that participated in the National Cancer Institute's Surveillance, Epidemiology, and End Results Program.

RESULTS

There were 5638 patients who developed secondary malignancies, significantly more than the endemic rate (O/E, 1.14; P<.001). Overall, irradiated patients had a similar risk of secondary malignancies compared with unirradiated patients (relative risk, 1.04; 95% confidence interval, 0.98‐1.10; P = .21). Irradiated patients had excess risk for sarcomas, breast cancers, and mesothelioma compared with unirradiated survivors (P<.05). Patients age <25 years at the time of their NHL diagnosis had the highest relative increased risk (no radiation: O/E, 2.1; P<.05; radiation: O/E, 4.51; P<.05). Overall, no statistical difference was observed for secondary cancer incidence between females and males (O/E, 1.12 vs. 1.15, respectively). Female survivors of NHL were less likely to develop breast cancer than the general population (O/E, 0.85; P<.05), but women age <25 years at the time of their NHL diagnosis were more likely to develop breast cancer (no radiation: O/E, 2.1; P<.05; radiation: O/E, 4.51; P<.05).

CONCLUSIONS

The overall risk of secondary malignancies was increased for NHL survivors and varied according to age at NHL diagnosis, gender, and treatment. Cancer 2006. © 2006 American Cancer Society.
Method of random spots for generation of synthetic inhomogeneous turbulent fields with prescribed autocorrelation functions
Authors: Kornev N. , Hassel E.
Published: May 2006

A new method for synthesis of artificial turbulent fields is proposed. The idea of the method is based on the representation of the turbulent field as a collection of randomly placed spots with an unknown inner distribution of velocity determined from the prescribed autocorrelation functions. The proposed algorithm generates fluctuations with prescribed spatial integral length scales, integral time scales, two‐point spatial and one‐point temporal autocorrelations, as well as one‐point cross correlations between fluctuation components. Copyright © 2006 John Wiley & Sons, Ltd.
Relativistic diffusions and Schwarzschild geometry
Authors: Franchi Jacques , Le Jan Yves
Published: May 2006

The purpose of this article is to introduce and study a relativistic motion whose acceleration, in proper time, is given by a white noise. We deal with general relativity and consider more closely the problem of the asymptotic behavior of paths in the Schwarzschild geometry example. © 2006 Wiley Periodicals, Inc.
A guaranteed minimum throughput service for TCP flows using measurement‐based admission control
Authors: Fàbrega Lluís , Jové Teodor , Vilà Pere , Marzo José
Published: May 2006

We propose a new scheme for a network service that guarantees a minimum throughput to flows accepted by admission control (AC). The whole scheme only uses a small set of packet classes in a core‐stateless network. At the ingress of the network each flow packet is marked into one of the sets of classes, and within the network, each class is assigned a different discarding priority. The AC method is based on edge‐to‐edge per‐flow throughput measurements using the first packets of the flow, and it requires flows to send with a minimum rate. We evaluate the scheme through simulations in a simple bottleneck topology with different traffic loads consisting of TCP flows that carry files of varying sizes. We use a modified TCP source with a new algorithm that forces the source to send with a minimum rate. We compare our scheme with the best‐effort service and we study the influence of the measurement duration on the scheme's performance. The results prove that the scheme guarantees the requested throughput to accepted flows and achieves a high utilization of network resources. Copyright © 2006 John Wiley & Sons, Ltd.
Performance analysis of a channel allocation scheme for multi‐service mobile cellular networks
Authors: Tang Shensheng , Li Wei
Published: May 2006

This paper presents a new channel allocation scheme, namely the dynamic partition with pre‐emptive priority (DPPP) scheme, for multi‐service mobile cellular networks. The system is modelled by a two‐dimensional Markov process and analysed by the matrix‐analytic method. A pre‐emptive priority (PP) mechanism is employed to guarantee the quality of service (QoS) requirement of the real‐time (RT) traffic at the expense of some degradation of non‐real‐time (NRT) traffic, while the victim buffer compensates the degradation and has no negative impact on the RT traffic. The complete service differentiation between new calls and handoff calls from different traffic classes is achieved by using the dynamic partition (DP) concept with the help of related design parameters. The performance analysis and numerical results show that the DPPP scheme, compared with the existing schemes, is effective and practical in multi‐service environments. Copyright © 2006 John Wiley & Sons, Ltd.
Inhibition of insulin secretion by cerulenin might be due to impaired glucose metabolism
Authors: Straub Susanne G. , Sharp Geoffrey W. G.
Published: May 2006

Background

Cerulenin, an inhibitor of protein acylation, has been used as a tool to study the potential role of protein acylation in a variety of activities in different cells, and in stimulus‐secretion coupling in pancreatic islets and clonal β‐cells.

Methods

In the present study we investigated its effects on stimulated insulin secretion, glucose metabolism and utilization, oxygen consumption and ATP levels.

Results

In isolated rat pancreatic islets, cerulenin pre‐treatment (100 µM) inhibited insulin secretion in response to glucose, and to the non‐hydrolysable analogue of leucine, aminobicyclo‐[2,2,1]heptane‐2‐carboxylic acid (BCH). These data are in accord with the hypothesis that protein acylation could be involved in the stimulation of insulin secretion. However, we also found that cerulenin profoundly decreased glucose oxidation, glucose utilization, oxygen consumption and ATP levels. Consequently, decreased metabolism provides an alternative mechanism to inhibition of protein acylation that could explain the inhibition of insulin secretion by cerulenin.

Conclusions

Inhibition of insulin secretion by cerulenin can no longer be taken as evidence in favour of a role for protein acylation in the control of insulin release. As protein acylation is known to be involved in the normal functioning of proteins in stimulus‐secretion coupling and exocytosis, more direct approaches to understand its role(s) are required. Copyright © 2006 John Wiley & Sons, Ltd.
Artificial Light‐Harvesting Systems by Use of Metal Coordination
Authors: Kobuke Yoshiaki
Published: May 2006

Construction of artificial light‐harvesting systems by metal coordination is reviewed. Light absorbing dyes include porphyrin, phthalocyanine, perylenebisimide and polypyridyl metal complexes. The supramolecular assemblies are obtained by ligand coordination to metal ions in the center or exterior of the chromophores. Supermolecules of discrete structures even in the solution phase are focused on, and methodologies to acquire large association constants are discussed. Complementary or multitopic coordination to the Zn2+ ion gives satisfactory results in obtaining stable and discrete supramolecular structures while maintaining the singlet excited state. Fast energy transfers among the chromophore units are analyzed satisfactorily to examine the properties of light‐harvesting antennae. Use of transition‐metal ions provides strong coordination, but intersystem crossing of the singlet excited state to the triplet becomes significant. Photophysical properties of such triplet excited species are reported in a limited number of cases and their properties are discussed in view of the light‐harvesting antenna function. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
DFT‐Verified Crystallographic Mechanism of Cycloplatination
Authors: Otto Stefanus , Chanda Arani , Samuleev Pavel V. , Ryabov Alexander D.
Published: May 2006

Two key intermediates in the mechanistic cycle of cycloplatination of aryl oximes by PtII complexes were crystallographically characterized. trans‐[PtCl2(SOMe2)(N‐acetophenone oxime)] is an active precursor on the C–H cleavage reaction coordinate. The formation of trans‐[PtCl2(N‐benzaldehyde oxime)2] accounts for the rate retardation by excess oxime. DFT calculations support the crystallographic evidence that provides unequivocal proof for the electrophilic nature of cycloplatination. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
Reservoir siltation in the semi‐arid highlands of northern Ethiopia: sediment yield–catchment area relationship and a semi‐quantitative approach for predicting sediment yield
Authors: Tamene L. , Park S. J. , Dikau R. , Vlek P. L. G.
Published: May 2006

Due to shortage of rainfall and its increasing variability, moisture stress is identified to be one of the most critical factors affecting agricultural productivity in the drylands of Ethiopia. To circumvent this problem, a strategy of supplemental irrigation through surface water harvesting was adopted by the government and several micro‐dams have been built in the semi‐arid parts of the country. However, the benefits from the water harvesting schemes are not sustainable because of rapid water storage loss due to siltation. There is, therefore, an urgent need for improved catchment‐based erosion control and sediment management strategies. The design and implementation of such strategies require data on the rate and magnitude of sediment deposition. To this end, reservoir surveys were conducted to estimate sediment deposition rate for 11 reservoirs identified to be representative of catchments in the Tigray region of northern Ethiopia. Two approaches were employed during the survey: one was based on measurement of sediment thickness in reservoirs while the other was based on comparing the original and existing topography of the reservoir‐beds. The average annual sediment yield estimated for the study sites was about 19 t ha−1 y−1. An equation of the type SSY = 3á36A0á67 (with SSY = area specific sediment yield in t ha−1 y−1 and A = catchment area in km2) was also established for the study region, which is opposite to the ‘universal’ SSY–A relationship. In order to improve the sediment yield predictive capability of A, it was integrated with a factorial index that assesses the catchment's propensity to erosion and potential sediment yield. The effect of accelerated sediment deposition on water storage loss of reservoirs and possible controlling factors of the SSY–A relationship are outlined. The potential semi‐quantitative scoring approach to characterize catchments in terms of erosion sensitivity and the significance of the A‐index approach to predict SSY of similar catchments are also highlighted. Copyright © 2006 John Wiley & Sons, Ltd.
Feature based image processing methods applied to bathymetric measurements from airborne remote sensing in fluvial environments
Authors: Carbonneau Patrice E. , Lane Stuart N. , Bergeron Normand
Published: May 2006

Bathymetric maps produced from remotely sensed imagery are increasingly common. However, when this method is applied to fluvial environments, changing scenes and illumination variations severely hinder the application of well established empirical calibration methods used to obtain predictive depth–colour relationships. In this paper, illumination variations are corrected with feature based image processing, which is used to identify areas in an image with a near‐zero water depth. This information can then be included in the depth–colour calibration process, which results in an improved prediction quality. The end product is an automated bathymetric mapping method capable of a 4 m2 spatial resolution with a precision of ±15 cm, which allows for a more widespread application of bathymetric mapping. Copyright © 2006 John Wiley & Sons, Ltd.
Holocene valley aggradation driven by river mouth progradation: examples from Australia
Authors: Rustomji Paul , Olley Jon , Chappell John
Published: May 2006

Since the end of the post‐glacial sea level rise 6800 years ago, progradation of river mouths into estuaries has been a global phenomenon. The responses of upstream alluvial river reaches to this progradation have received little attention. Here, the links between river mouth progradation and Holocene valley aggradation are examined for the Macdonald and Tuross Rivers in south‐eastern Australia. Optical and radiocarbon dating of floodplain sediments indicates that since the mid‐Holocene sea level highstand 6800 years ago vertical floodplain aggradation along the two valleys has generally been consistent with the rate at which each river prograded into its estuary. This link between river mouth progradation and alluvial aggradation drove floodplain aggradation for many tens of kilometres upstream of the estuarine limits. Both rivers have abandoned their main Holocene floodplains over the last 2000 years and their channels have contracted. A regional shift to smaller floods is inferred to be responsible for this change, though a greater relative sea level fall experienced by the Macdonald River since the mid‐Holocene sea level highstand appears to have been an additional influence upon floodplain evolution in this valley. Copyright © 2006 John Wiley & Sons, Ltd.
River channel dynamics following extirpation of wolves in northwestern Yellowstone National Park, USA
Authors: Beschta Robert L. , Ripple W. J.
Published: May 2006

Historical records indicate that gray wolves (Canis lupus) were extirpated from the upper Gallatin River Basin in the early 1900s. Following the removal of these large carnivores, elk (Cervis elaphus) began to increasingly browse streamside vegetation in the winter range, causing widespread loss of formerly extensive willow (Salix spp.) communities. Historical aerial photographs and chronosequences of ground photographs were used to characterize general changes in vegetation and channel morphology over time. In August of 2004, riparian vegetation and channel cross‐sections were surveyed along three reaches of the upper Gallatin River. Reach A was located upstream of the elk winter range (control reach) whereas reaches B and C (treatment reaches) were located within the elk winter range. Willow cover on floodplains averaged 85 per cent for reach A, but only 26 per cent and 5 per cent for reaches B and C, respectively. The average return period of calculated bankfull discharges was 3·1 yrs for reach A but increased to 32·4 yrs and 10·6 yrs for reaches B and C, respectively. The long‐term loss of streamside vegetation allowed channels to generally increase in hydraulic capacity (via increases in width, incision or both) and decrease their hydrologic connectivity with adjacent floodplains. This study documents, perhaps for the first time, the resultant impacts to riparian vegetation functions and stream channel characteristics following the extirpation of a large mammalian carnivore. Copyright © 2006 John Wiley & Sons, Ltd.
Differentiating past events on a cone influenced by debris‐flow and snow avalanche activity – a dendrogeomorphological approach
Authors: Stoffel Markus , Bollschweiler Michelle , Hassler Gion‐Reto
Published: May 2006

Dendrogeomorphology was used to investigate past events on a cone affected by both debris flows and snow avalanches. We report on results of 520 cores from 251 injured Larix decidua Mill. and Picea abies (L.) Karst. trees sampled on the Birchbach cone (Swiss Alps). Detailed analysis of tree‐ring sequences allowed dating of 561 growth disturbances in individual trees for a 252 yr period, extending from 1750 to 2002, which could be attributed to 30 different event years. We then localized the position of rows of traumatic resin ducts (TRDs) within the tree ring so as to assess the intra‐seasonal position of damage. In agreement with data on the local growth period, TRDs located at the beginning of the new growth ring were considered the result of avalanche impacts that occurred during the dormant season or in earliest earlywood between late October and early May. In contrast, TRD found in late earlywood or within latewood were considered the result of periglacial debris‐flow activity, as these layers of the tree ring are locally formed between July and early October.

For nine out of the 30 reconstructed event years, the intra‐seasonal timing of TRDs indicated that reactions must be the result of past snow avalanche activity. In 19 other event years, TRDs showed that damage has been caused between July and early October and, thus, through debris flows in the Birchbach torrent. Finally, the spatial patterns of trees showing reactions as a result of particular events were assessed so as to approximate the extent of past debris flows and snow avalanches. Copyright © 2006 John Wiley & Sons, Ltd.
Morphodynamics and climate controls of two aeolian blowouts on the northern Great Plains, Canada
Authors: Hugenholtz C. H. , Wolfe S. A.
Published: May 2006

Blowouts are the most regionally pervasive active aeolian landform on the northern Great Plains of North America. This study reports a long‐term investigation into the morphological development of two adjacent blowouts in a continental dune field. The blowouts were monitored for a decade in the Bigstick Sand Hills of southwestern Saskatchewan, Canada. Topographic changes were determined from dense arrays of erosion pins in each blowout (1 per 4 m2, n = 171; and 1 per 16 m2, n = 150). Pin measurements were made 16 times between May 1994 and May 2004. Over the decade both blowouts expanded and more than doubled in volume. Differences in form–flow interactions have caused the larger of the two blowouts to deposit more than a metre of sediment within the deflation basin, and the smaller blowout to erode by more than a metre. A negative feedback effect was triggered when the larger blowout reached a critical size around 1994 (60 m × 36 m × 8·1 m, length × width × height) when sediment was no longer eroded from the deflation basin. A positive feedback in the smaller blowout continues to facilitate erosion from the deflation basin. Monthly observations since 2002 indicate that aspect plays an important role in the development of these blowouts by creating a spatial asymmetry in sediment availability. Sediment is more readily available throughout the year on south‐facing slopes, which receive greater insolation than north‐facing slopes and are often drier and more frequently thawed in this cold‐climate environment. Comparisons between climate data from a remote meteorological station 45 km to the southwest and sediment transport indices developed from the erosion pin data produced very few correlations significant at the 95 per cent confidence level. Nevertheless, the signs of the correlation coefficients indicate that sediment erosion and deposition in both blowouts respond similarly to the following climate variables recorded at the remote station: (i) the amount of precipitation, (ii) the transport capacity of the wind and (iii) transporting winds from a directional wedge between 180 and 330°. Taken altogether, the results from this study highlight the importance of climate and feedback effects in blowout development that may be extended to other blowouts in continental and coastal settings. Copyright © 2006 John Wiley & Sons, Ltd.
Physical modelling of fault scarp degradation under freeze–thaw cycles
Authors: Font M. , Lagarde J.‐L. , Amorese D. , Coutard J.‐P. , Dubois A. , Guillemet G. , Ozouf J.‐C. , Vedie E.
Published: May 2006

Physical modelling has been developed in order to simulate the effects of periglacial erosion processes on the degradation of slopes and scarps. Data from 41 experimental freeze–thaw cycles are presented. They attest to the efficiency of periglacial processes that control both erosion and changes in scarp morphology: (i) cryoexpulsion leads to an increase of scarp surface roughness and modifies significantly the internal structure of the active layer; (ii) combined effects of frost creep and gelifluction lead to slow and gradual downslope displacements of the active layer (0·3 cm/cycle); (iii) debris flows are associated with the most significant changes in scarp morphology and are responsible for the highest rate of scarp erosion; (iv) quantification of the erosion rate gives values close to 1 cm3 cm−2 for 41 freeze–thaw cycles. These experimental results are consistent with field data acquired along the La Hague fault scarp (Normandy, France) where an erosion rate of 4·6 ± 1 m3 m−2 per glacial stage has been computed from the volume of natural slope deposits stored during the Weichselian glacial stage. These results show that moist periglacial erosion processes could lead to an underestimation of Plio‐Quaternary deformation in the mid‐latitudes. Copyright © 2006 John Wiley & Sons, Ltd.
Experimental determination of saltating glass particle dispersion in a turbulent boundary layer
Authors: Wang H. T. , Zhang X. H. , Dong Z. B. , Ayrault M.
Published: May 2006

A horizontal saltation layer of glass particles in air is investigated experimentally over a flat bed and also over a triangular ridge in a wind tunnel. Particle concentrations are measured by light scattering diffusion (LSD) and digital image processing, and velocities using particle image velocimetry (PIV). All the statistical moments of the particle concentration are determined such as mean concentration, root mean square concentration fluctuations, skewness and flatness coefficients. Over the flat bed, it is confirmed that the mean concentration decreases exponentially with height, the mean dispersion height being a significant length scale. It is shown that the concentration distribution follows quite well a lognormal distribution. Over the ridge, measurements were made at the top of the ridge and in the cavity region and are compared with measurements without the ridge. On the hill crest, particles are retarded, the saltation layer decreases in thickness and concentration is increased. Downwind of the ridge, particle flow behaves like a jet, in particular no particle return flow is observed. Copyright © 2006 John Wiley & Sons, Ltd.
Erosion in northwest Tibet from in‐situ‐produced cosmogenic 10Be and 26Al in bedrock
Authors: Kong Ping , Na Chunguang , Fink David , Ding Lin , Huang Feixin
Published: May 2006

Concentrations of in‐situ‐produced cosmogenic nuclides 10Be and 26Al in quartz were measured by accelerator mass spectrometry for bedrock basalts and sandstones located in northwest Tibet. The effective exposure ages range between 23 and 134 ka (10Be) and erosion rates between 4·0 and 24 mm ka−1. The erosion rates are significantly higher than those in similarly arid Antarctica and Australia, ranging between 0·1 and 1 mm ka−1, suggesting that precipitation is not the major control of erosion of landforms. Comparison of erosion rates in arid regions with contrasting tectonic activities suggests that tectonic activity plays a more important role in controlling long‐term erosion rates. The obtained erosion rates are, however, significantly lower than the denudation rate of 3000–6000 mm ka−1 beginning at c. 5‐3 Ma in the nearby Godwin Austen (K2) determined by apatite fission‐track thermochronology. It appears that the difference in erosion rates within different time intervals is indicative of increased tectonic activity at c. 5–3 Ma in northwest Tibet. We explain the low erosion rates determined in this study as reflecting reduced tectonic activity in the last million years. A model of localized thinning of the mantle beneath northwest Tibet may account for the sudden increased tectonic activity at c. 5–3 Ma and the later decrease. Copyright © 2006 John Wiley & Sons, Ltd.
Essential oil composition of Pimpinella affinis Ledeb. from two localities in Iran
Authors: Askari F. , Sefidkon F.
Published: May 2006

Essential oils were isolated by hydrodistillation from the stems plus leaves, inflorescences and seeds of Pimpinella affinis Ledeb. individually. The plants were collected from Khojir and Chaloos (north‐east and north of Tehran province, respectively). The yields of stem plus leaf, inflorescence and seed oils for the Khojir samples were 0.04%, 1.98% and 5.33% w/w and for the Chalous samples were 0.37%, 1.74% and 4.05% w/w, respectively. Limonene is a major constituent in the inflorescence and seed oils of the Khojir (47.9% and 90.5%, respectively) and Chalous samples (37.8% and 70.8%, respectively), whereas it was found in the stem plus leaf oil of the Khojir and the Chalous samples in low amounts (1.4% and 0.8%, respectively). γ‐Terpinen‐7‐al is the major constituent in the stem plus leaf and inflorescence oils of the Khojir (69.9% and 37.6%) and Chalous samples (72.8% and 49.1%), but was not found at all in the seed oils. Caryophyllene oxide (9.1%) was found in the stem plus leaf oil of the Khojir sample, and methyl eugenol (9.7%) and (E)‐nerolidol acetate (9.1%) in the seed oil of the Chalous sample. Copyright © 2006 John Wiley & Sons, Ltd.
RNA interference‐based functional dissection of the 17q12 amplicon in breast cancer reveals contribution of coamplified genes
Authors: Kao Jessica , Pollack Jonathan R.
Published: May 2006

DNA amplification is a frequent occurrence in cancer genomes. While tumor amplicons may harbor known oncogenes “driving” amplification, amplicons rarely comprise only single genes. The potential functional contribution of coamplified genes remains largely unexplored. In breast cancer, 20–30% of tumors exhibit amplification within chromosome band 17q12, containing the ERBB2 oncogene. Analysis of array‐based comparative genomic hybridization and expression profiling data indicate that the minimum region of recurrent amplification (i.e., the amplicon “core”) at 17q12 includes two other genes, GRB7 and STARD3, which exhibit elevated expression when amplified. Western blot analysis confirms overexpression of each at the protein level in breast cancer cell lines SKBR3 and BT474 harboring amplification. In these cell lines (but not in control MCF7 breast cancer cells lacking 17q12 amplification), targeted knockdown of ERBB2 expression using RNA interference (RNAi) methods results in decreased cell proliferation, decreased cell‐cycle progression, and increased apoptosis. Notably, targeted knockdown of either GRB7 or STARD3 also leads to decreased cell proliferation and cell‐cycle progression, albeit to a lesser extent compared with ERBB2 knockdown. We conclude that the amplification and resultant overexpression of genes coamplified with ERBB2 at 17q12 can contribute to proliferation levels of breast cancer cells. Our findings validate the utility of RNAi in the functional interrogation of tumor amplicons, and provide evidence for a contribution of coamplified genes to tumor phenotypes. © 2006 Wiley‐Liss, Inc.
CpG island methylation of genes accumulates during the adenoma progression step of the multistep pathogenesis of colorectal cancer
Authors: Kim Young‐Ho , Petko Zsolt , Dzieciatkowski Slavomir , Lin Li , Ghiassi Mahan , Stain Steve , Chapman William C. , Washington Mary Kay , Willis Joseph , Markowitz Sanford D. , Grady William M.
Published: May 2006

Genetic alterations occur during the adenoma‐carcinoma sequence of colon cancer formation and drive the initiation and progression of colon cancer formation. The aberrant methylation of genes is an alternate, epigenetic mechanism for silencing tumor suppressor genes in colon cancer. The aim of this study was to determine on a global and gene‐specific level the role of CpG island methylation in the initiation and progression of colon cancer. Consequently, we assessed the frequency of gene methylation in tumors representative of the commonly recognized histological steps of the adenoma‐carcinoma progression sequence through the analysis of eight genes previously identified to be methylated in colon cancer, MGMT, HLTF, MLH1, p14ARF, CDKN2A, TIMP3, THBS1, and CDH1. We observed that the proportion of tumors carrying methylated alleles increased from adenomas to adenocarcinomas but that the proportion of tumors with methylated alleles was not different between adenocarcinomas and metastases (69% versus 90%, P = 0.01 and 90% versus 81%, P > 0.05). The most substantial difference occurred between early and advanced adenomas (47% versus 84%, P = 0.018). Furthermore, we observed that the frequency of gene methylation at the different steps of the progression sequence varied between genes. Thus, the aberrant methylation of genes appears to increase most significantly during the progression of early adenomas to advanced adenomas, and the frequency of specific gene methylation at the different steps of the adenoma‐carcinoma progression sequence varies in a gene‐specific fashion. © 2006 Wiley‐Liss, Inc.