bluuebunny/crossref_metadata_2025 huggingface dataset:
Measurements of UWB through‐the‐wall propagation using spectrum analyzer and the Hilbert transform
Authors: Hussein Muqaibel Ali
Published: December 2007

This article presents a simplified approach for characterization of ultra wideband (UWB) through‐the‐wall propagation. The simplified approach requires spectrum analyzer rather than vector network analyzer. A minimum phase retrieval method based on Hilbert transform is used to retrieve the phase information. The proposed method is shown to be applicable to the insertion transfer function. While linear phase component cannot be retrieved, important factors for UWB receiver design such as group delay ripple and dispersion effect can be retrieved. In noisy channels, phase retrieval could be superior to direct phase measurements. Estimation of linear phase component can be achieved through matching the measured phase with the retrieved phase. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 465–470, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23107
Empirical propagation model for WiMAX at 3.5 GHz in an urban environment
Authors: Valcarce Rial Álvaro , Krauss Harald , Hauck Joachim , Buchholz Martin , Aguado Agelet Fernando
Published: December 2007

Many Worldwide interoperability for microwave access (WiMAX) field trials are currently taken place around the world. In some countries, commercial WiMAX networks are running. This article presents an empirical propagation model obtained from a pilot project in Saarbruecken. Results of the extensive measurement campaign of this WiMAX trial in an urban environment, operating at a frequency of 3.5 GHz, are presented and compared to own field strength predictions. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 483–487, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23112
Retro‐directive array using two‐port dual polarized elements
Authors: Chang The Nan , Wu Jut‐Shuan
Published: December 2007

In this article, linear and circular polarized retro‐directive arrays with two‐port dual‐polarized elements are implemented. Pair of elements is arranged so that each vertical port is connected to the horizontal port and vice versa. In this way, reflection field from the ground plane and the reradiated field by way of interconnection can easily be distinguished not only for the linear polarized array but also for the circular polarized array. Simulations and experiments were conducted at 5 and 10 GHz for 2D linear and circular polarized array. respectively. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 450–453, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23113
Polyaniline as an automatic beam steering material
Authors: Menon Rajesh , Thomas Rinku M , John Honey , Joseph Rani , Mathew K. T.
Published: December 2007

This study deals with a preliminary study of automatic beam steering property in conducting polyaniline. Polyaniline in its undoped and doped state was prepared from aniline by the chemical oxidative polymerization method. Dielectric properties of the samples were studied at S‐band microwave frequencies using cavity perturbation technique. It is found that undoped polyaniline is having greater dielectric loss and conductivity compared with the doped samples. The beam steering property is studied using a perspex rod antenna and HP 8510C vector network analyzer. The shift in the radiated beam is studied for different d.c voltages. The results show that polyaniline is a good material for beam steering applications. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 422–425, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23115
An influence of current leakage on characteristics of quantum well laser
Authors: Matavulj P. S. , Timotijević B. Dj.
Published: December 2007

Significant changes in quantum well laser performances when current leakage is not neglected are reported. Leakage effect is included extending three‐level rate equations. Derived SPICE model is used to optimize and improve the most important parameters of single quantum well lasers: threshold current, cutoff frequency, and turn‐on delay time. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 479–483, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23121
Printed UWB pellet‐shape microstrip‐fed monopolar antenna for 3.1 to 17 GHz
Authors: Chan C. H. , Lee T. K. , Chan W. S.
Published: December 2007

A printed pellet‐shape microstrip‐fed monopolar antenna is proposed for portable UWB devices. An impedance bandwidth of 138.3% within the frequency range of 3.1 –17 GHz for S11 < −10 dB is achieved. Positive gain and constant group delay are obtained with omnidirectional radiation pattern. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 490–494, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23128
A new analytical method to extract the small‐signal equivalent circuit of high frequency FET transistors
Authors: Olvera Cervantes J. L. , Medina Monroy J. L. , Chávez Pérez R. A. , Velázquez Ventura A.
Published: December 2007

A new set of simply analytical equations is proposed as an alternative method to calculate the intrinsic transistor elements of an extended model for microwave FET's. This method is based on Y‐parameters as well as on a new process to determine the differential resistances Rfsand Rfd, including the frequency effect, in such way that measurements at very low frequencies are not required and long iterative methods are avoided. The method was applied to FET's transistors and the validity of the model is certified by direct comparison with measured data from 1 to 45 GHz. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 453–457, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23130
Modified slot bow‐tie antenna for UWB applications
Authors: Mehdipour Aidin , Mohammadpour‐Aghdam Karim , Faraji‐Dana Reza , Sebak Abdel‐Razik
Published: December 2007

A modified slot Bow‐Tie antenna is presented in this article. The presented modified antenna shows improvement in the VSWR previous reported results. Moreover, the dispersion characteristics of the antenna both in frequency and time domains have been analyzed and illustrated as well. The satisfactory agreement between experimental and simulation results proves the applicability of the antenna in UWB communications. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 429–432, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23131
Characteristic impedance of a novel TEM cell used for microwave chemistry experiment
Authors: Yang Yang , Huang Kama
Published: December 2007

New experimental devices with uniform electromagnetic field distribution are needed in the kinetic studies of microwave chemistry. Here a novel transverse electromagnetic (TEM) cell is proposed. The shape of the TEM cell is different from the conventional TEM cells, and it has a higher cutoff frequency of the first TE‐mode than the conventional one with the same outer dimension and a larger area of uniform electromagnetic fields than the conventional one with the same cutoff frequency. The conformal mapping method was used to calculate the characteristic impedance of the TEM cell. The finite element method was used to confirm the analytical solutions. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 525–529, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23135
Complete 1H and 13C NMR assignments and Z/E‐stereoconfiguration determination of isomers of 1,4‐diketone derivatives
Authors: Xu Guohua , Yin Guodong , Guo Wenbo , Wu Anxin , Cui Yanfang
Published: December 2007

Complete 1H and 13C NMR assignments and Z/E‐stereoconfiguration determination for a series of new isomers of 1,4‐diketone derivatives obtained via self‐sorting tandem reaction were accomplished by means of one‐ and two‐dimentional NMR experiments including 1H, 13C, gCOSY, gHSQC, gHMBC, and NOESY. Copyright © 2008 John Wiley & Sons, Ltd.
Neutral zinc(II)O,O‐di‐alkyldithiopho‐ sphates—variable temperature31P NMR and quantum chemical study of the ZDDP monomer–dimer equilibrium
Authors: Harrison J. J. , Chan C. Y. , Onopchenko A. , Pradhan A. R. , Petersen M.
Published: December 2007

A full line‐shape analysis of the VT31P NMR spectra was carried out for the monomer–dimer equilibrium of neutral ZDDP. The energy surface and the energetics of the monomer‐dimer equilibrium (ΔH° , ΔG° ,Ea, ΔH≠, and ΔG≠) are reported for three variants wherein the alkyl groups in the ZDDP are 2‐ethylhexyl, isopropyl, and isobutyl.

We explored a reaction pathway between the monomer and dimer form by means of density functional theory (DFT). The linear combination of atomic orbitals (LCAO) code DMol3was used together with a synchronous transient method to effectively locate transition states. Vibrational eigenmodes of all intermediates were computed to capture finite temperature effects. Methyl and ethyl were considered as alkyl groups. Two novel intermediates were located—a four‐membered ring and a six‐membered ring intermediate along the reaction coordinate. Comparison of the experimentally derived and computed energy surfaces was carried out. Copyright © 2007 John Wiley & Sons, Ltd.
Active runout cancellation for fine‐seeking control in optical disk drives
Authors: Liu Jieng‐Jang , Yang Yee‐Pien
Published: December 2007

The fine‐seeking control, one of the radial positioning servo functions on the optical disk drives, seeks a limited number of tracks forward or backward. Two properties, noted as controllable seeking velocity and achievable settling, are important issues for fine‐seeking performance. Unless these performances are satisfied, the settling down track cannot be guaranteed to be the desired track; hence, additional seeking is required to come forward to the destination track. Owing to the periodic runout effects, the conventional feedback approaches are difficult to achieve stable velocity control and satisfactory settling performance for high spindle speed operation. This paper proposes the extended usage of frequency adaptive control technique (FACT) for active runout suppression on fine seeking. It is shown that the runout effects can be isolated from the servo systems as long as the FACT is applied. A mode switching control approach is then introduced to switch the adaptation between the track‐following and fine‐seeking processes. This leads to an efficient compensation for periodic runout, thereby eliminating the direction hysteresis in fine seeking. Experimental results are shown to be effective for the performance on both velocity control and settling behavior after seeking. Copyright © 2007 John Wiley & Sons, Ltd.
Identification of membrane‐associated proteins from Campylobacter jejuni strains using complementary proteomics technologies
Authors: Cordwell Stuart J. , Len Alice C. L. , Touma Rachel G. , Scott Nichollas E. , Falconer Linda , Jones David , Connolly Angela , Crossett Ben , Djordjevic Steven P.
Published: December 2007

Campylobacter jejuni is the leading cause of food‐ and water‐borne illness world‐wide. The membrane‐associated proteome of a recent C. jejuni gastrointestinal isolate (JHH1) was generated by sodium carbonate precipitation and ultracentrifugation followed by 2‐DE and MALDI‐TOF MS as well as 2‐DLC (strong cation exchange followed by RP chromatography) of trypsin digests coupled to MS/MS (2‐DLC/MS/MS). 2‐DE/MS identified 77 proteins, 44 of which were predicted membrane proteins, while 2‐DLC/MS/MS identified 432 proteins, of which 206 were predicted to be membrane associated. A total of 453 unique proteins (27.4% of the C. jejuni theoretical proteome), including 187 bona fide membrane proteins were identified in this study. Membrane proteins were also compared between C. jejuni JHH1 and ATCC 700297 to identify factors potentially associated with increased gastrointestinal virulence. We identified 28 proteins that were significantly (>two‐fold) more abundant in, or unique to, JHH1, including eight proteins involved in chemotaxis signal transduction and flagellar motility, the amino acid‐binding surface antigens CjaA and CjaC, and four outer membrane proteins (OMPs) of unknown function (Cj0129c, Cj1031, Cj1279c, and Cj1721c). Immunoblotting using convalescent patient sera generated postgastrointestinal infection revealed 13 (JHH1) and 12 (ATCC 700297) immunoreactive proteins. These included flagellin (FlaA) and CadF as well as Omp18, Omp50, Cj1721c, PEB1A, PEB2, and PEB4A. This study provides a comprehensive analysis of membrane‐associated proteins from C. jejuni.
Proteomic profiling using mass spectrometry – does normalising by total ion current potentially mask some biological differences?
Authors: Cairns David A. , Thompson Douglas , Perkins David N. , Stanley Anthea J. , Selby Peter J. , Banks Rosamonde E.
Published: December 2007

Normalisation of data to minimise the impact of technical variation on comparative sample analysis is often carried out. Using SELDI data as a model, we have examined the effects of normalisation by TIC which is commonly used for MS data. Significant intergroup differences in normalisation factor were found for serum profiles which could not be explained by experimental factors, implying that normalisation by TIC may in some situations also normalise biological differences and should be systematically evaluated.
Post alignment clustering procedure for comparative quantitative proteomics LC‐MS Data
Authors: de Groot Joost C. W. , Fiers Mark W. E. J. , van Ham Roeland C. H. J. , America Antoine H. P.
Published: December 2007

Comparative LC‐MS is a powerful method for detailed quantitative comparison of complex protein mixtures. Dedicated software is required for detection, matching, and alignment of peaks in multiple LC‐MS datasets. However, retention time shifts, saturation effects, limitations of experimental accuracy, and possible occurrence of split peaks make it difficult for software to perfectly match all chromatograms. We describe a procedure to assess the above problems and show that dataset quality can be enhanced with the aid of cluster analysis.
Protein Information Crawler (PIC): Extensive spidering of multiple protein information resources for large protein sets
Authors: Mayer Ulrich
Published: December 2007

Proteomic studies often produce sets of hundreds of proteins. Bioinformatic information for these large protein sets must be collected from multiple online resources. Protein Information Crawler (PIC) automatically bulk‐collects such data from multiple databases and prediction servers, based on National Center for Biotechnology Information (NCBI) gi numbers or accession numbers, and summarizes them in a Microsoft Excel® spreadsheet and/or HTML table. PIC greatly accelerates information procurement, helps to build customized protein information databases and drastically reduces manual database investigation in extensive proteomic studies. Availability: http://www.zoo.uni‐heidelberg.de/mfa/PIC.
Vesicular and tubular structures prepared from self‐assembly of novel amphiphilic ABA triblock copolymers in aqueous solutions
Authors: Tian Zhen , Li Haibin , Wang Meng , Zhang Aiying , Feng Zeng‐Guo
Published: December 2007

A kind of novel soft amphiphilic ABA triblock copolymers, poly(L‐lysine)‐b‐poly(tetrahydrofuran)‐b‐poly(L‐lysine), was synthesized by the anionic ring‐opening polymerization of ε‐benzyloxycarbonyl‐L‐lysine N‐carboxyanhydride using amine‐terminated poly(tetrahydrofuran) as a macroinitiator and subsequent removal of the protecting group. The resulting copolymers possessing a nearly symmetrical and narrow molecular weight distribution were dissolved in water at an appropriate concentration range at room temperature to yield vesicles as confirmed by using negative stain TEM and DLS. Meanwhile, nanotubes were obtained as the result of the conjunction of vesicles by reducing the medium temperature as evidenced by TEM. The effect of pH and salt concentration variations on the self‐assembly behavior was also examined. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 1042–1050, 2008
Rheological and thermal properties of agarose aqueous solutions and hydrogels
Authors: Fernández Emiliano , López Daniel , Mijangos Carmen , Duskova‐Smrckova Miroslava , Ilavsky Michal , Dusek Karel
Published: December 2007

In this article, we report on the rheological properties of agarose aqueous solutions and gels. Viscosity curves were determined for homogeneous agarose aqueous solutions at different temperatures (from 68 to 38 °C) to study the viscosity behavior as the systems undergo gelation. The gelation phenomenon of agarose solutions was also investigated by shear oscillation experiments and differential scanning calorimetry. The gelation and melting temperature as a function of agarose concentration were determined together with the gelation and melting enthalpies. The results obtained were interpreted using the two‐step model describing the gelation of agarose in water. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 322–328, 2008
Correlations in single‐photon experiments
Authors: Varró S.
Published: December 2007

Correlations of detection events in two photodetectors placed at the opposite sides of a beam splitter are studied in the frame of classical probability theory. It is assumed that there is always only one photon present in the measuring apparatus during one elementary experiment (one measurement act). Due to the conservation of energy, there is always a strict anticorrelation in one elementary experiment, because the photon cannot excite both of the detectors at the same time. It is explicitely shown in several examples that the “bunching” and “anti‐bunching” of the counts in serieses of elementary single‐photon experiments is governed by the statistical properties of grouping the sequences of the elementary measurements.
On the dynamic deformation of porous Cosserat linear–thermoelastic shells
Authors: Bîrsan M.
Published: December 2007

This paper is concerned with the linear theory of porous Cosserat thermoelastic shells. We consider anisotropic and inhomogeneous shells and establish the existence and uniqueness of solution to the boundary–initial–value problem associated to the dynamic deformations. To this aim, we employ the semigroup of linear operators theory.
Harvest‐based Bayesian estimation of sika deer populations using state‐space models
Authors: Yamamura Kohji , Matsuda Hiroyuki , Yokomizo Hiroyuki , Kaji Koichi , Uno Hiroyuki , Tamada Katsumi , Kurumada Toshio , Saitoh Takashi , Hirakawa Hirofumi
Published: December 2007

We have estimated the number of sika deer,Cervus nippon, in Hokkaido, Japan, with the aim of developing a management program that will reduce the level of agricultural damage caused by these deer. A population index that is defined by the population divided by the population of 1993 is first estimated from the data obtained during a spotlight survey. A generalized linear mixed model (GLMM) with corner point constraints is used in this estimation. We then estimate the population from the index by evaluating the response of index to the known amount of harvest, including hunting. A stage‐structured model is used in this harvest‐based estimation. It is well‐known that estimates of indices suffer from large observation errors when the probability of the observation fluctuates widely; therefore, we apply state‐space modeling to the harvest‐based estimation to remove the observation errors. We propose the use of Bayesian estimation with uniform prior‐distributions as an approximation of the maximum likelihood estimation, without permitting an arbitrary assumption that the parameters fluctuate following prior‐distributions. We are able to demonstrate that the harvest‐based Bayesian estimation is effective in reducing the observation errors in sika deer populations, but the stage‐structured model requires many demographic parameters to be known prior to running the analyses. These parameters cannot be estimated from the observed time‐series of the index if there is insufficient data. We then construct a univariate model by simplifying the stage‐structured model and show that the simplified model yields estimates that are nearly identical to those obtained from the stage‐structured model. This simplification of the model simultaneously clarifies which parameter is important in estimating the population.
A novel member of the ligand-gated chloride channel gene family from Haemonchus contortus
Authors: FORRESTER S. G. , SIDDIQUI S. Z.
Published: December 2007

Ligand-gated chloride channels (LGCCs) are key components of the nervous system of parasitic nematodes and important targets for anthelmintics. Here, we describe the isolation and characterization of a novel member of the LGCC gene family (HcLGCC1) from the parasitic nematode Haemonchus contortus. Sequence analysis revealed that the channel subunit encoded by HcLGCC1 is anion selective and a member of a group of channels characterized as having two Cys-loops in the N-terminal ligand-binding domain†. Although the overall function of HcLGCC1 is presently unknown, the gene may play a key role in the early developmental stages of the parasite. Further investigations into the function of LGCCs, such as HcLGCC1, in parasitic nematodes should have implications for the discovery of new anthelmintic targets.
EVALUATIVE CONCEPTS AND OBJECTIVE VALUES: RAND ON MORAL OBJECTIVITY
Authors: Wright Darryl F.
Published: December 2007

Those familiar with Ayn Rand's ethical writings may know that she discusses issues in metaethics, and that she defended the objectivity of morality during the heyday of early non-cognitivism. But neither her metaethics, in general, nor her views on moral objectivity, in particular, have received wide study. This article elucidates some aspects of her thought in these areas, focusing on Rand's conception of the way in which moral values serve a biologically based human need, and on her account of moral values as both essentially practical and epistemically objective in a sense fundamentally continuous with the objectivity of science. The bearing of her epistemological writings on her ethical thought is emphasized throughout, and her epistemology is defended against a line of criticism inspired by John McDowell's criticism of the so-called “myth of the given.”
ARISTOTELIAN CONSTRUCTIVISM
Authors: LeBar Mark
Published: December 2007

Constructivismabout practical judgments, as I understand it, is the notion that our true normative judgments represent a normative reality, while denying that that reality is independent of our exer-cise of moral and practical judgment. The Kantian strain of practical constructivism (through Kant himself, John Rawls, Christine Korsgaard, and others) has been so influential that it is tempting to identify the constructivist approach in practical domains with the Kantian development of the out-look. In this essay I explore a somewhat different variety of practical constructivism, which I callAristotelian Constructivism. My aim is to establish conceptual space for this form of constructivism by indicating both in what ways it agrees with its Kantian counterparts and in what ways it differs. I argue that Aristotelian Constructivism is on one sense more faithful to the constructivist enterprise than the Kantian varieties, in that its understanding of both the establishment of practical truthandthe vindication of the theory itself is constructivist.
Split of attentional resources in human visual cortex
Authors: MORAWETZ CARMEN , HOLZ PETRA , BAUDEWIG JUERGEN , TREUE STEFAN , DECHENT PETER
Published: December 2007

Visual spatial attention has been described as a process that favors the processing of sensory information that falls into the “spotlight of attention.” Recent studies have provided support for an ability to split this attentional focus to selectively process spatially separate locations. Using functional magnetic resonance imaging, the signature for the presence of multiple spotlights is the presence of multiple retinotopically specific foci of activation in striate and extrastriate visual areas. We used this approach to investigate the presence of such separable activations as a function of the eccentricity of the spatial foci of attention. Visual stimuli consisted of letters and digits displayed in rapid serial visual presentation (RSVP). Five RSVP streams were presented simultaneously, one in the center of the visual field and one in each visual field quadrant. Subjects had to deploy their attention either to a single peripheral location or two non-contiguous regions performing a match-mismatch judgment. The results show that dividing attention leads to multiple spotlights of attention for central as well as more peripheral locations of the visual field. However, depending on the exact location and width of the attentional spotlights, resulting activation maps might reveal merged activation patterns even in the presence of distinct attentional spotlights.
Development of cortical responses to optic flow
Authors: GILMORE RICK O. , HOU C. , PETTET M.W. , NORCIA A.M.
Published: December 2007

Humans discriminate approaching objects from receding ones shortly after birth, and optic flow associated with self-motion may activate distinctive brain networks, including the human MT+ complex. We sought evidence for evoked brain activity that distinguished radial motion from other optic flow patterns, such as translation or rotation by recording steady-state visual evoked potentials (ssVEPs), in both adults and 4–6 month-old infants to direction-reversing optic flow patterns. In adults, radial flow evoked distinctive brain responses in both the time and frequency domains. Differences between expansion/contraction and both translation and rotation were especially strong in lateral channels (PO7 and PO8), and there was an asymmetry between responses to expansion and contraction. In contrast, infants' evoked response waveforms to all flow types were equivalent, and showed no evidence of the expansion/contraction asymmetry. Infants' responses were largest and most reliable for the translation patterns in which all dots moved in the same direction. This pattern of response is consistent with an account in which motion processing systems detecting locally uniform motion develop earlier than do systems specializing in complex, globally non-uniform patterns of motion, and with evidence suggesting that motion processing undergoes prolonged postnatal development.
Herz und Sport: wann wird es gefährlich?
Authors: Keller
Published: December 2007

Eine regelmässige sportliche Betätigung übt viele positive Effekte auf das kardiovaskuläre und andere Systeme aus. Die Schattenseite des Sports (nicht nur Hochleistungs-, sondern auch Amateursport) ist der plötzliche Herztod, ein dramatisches Ereignis für den Patienten und seine Familie. Viele kardiale Erkrankungen, die zum plötzlichen Herztod führen, sind hereditär. Eine der häufigsten Ursachen für den plötzlichen Herztod ist die autosomal-dominant vererbbare hypertrophe Kardiomyopathie mit ihrer ausgeprägten Phänotyp- und Genotypheterogenität. Dieses Krankheitsbild wird im Folgenden vorgestellt. Um den plötzlichen Herztod bei Sportlern zu verhindern, ist ein strukturiertes kardiovaskuläres Screening zu Beginn der sportlichen Laufbahn notwendig. Wenn eine hereditäre, mit dem plötzlichen Herztod assoziierte, kardiale Erkrankung diagnostiziert wird, ist zudem ein Familienscreening indiziert.
Subklinische Störungen der Schilddrüsenfunktion
Authors: Stöckli
Published: December 2007

Subklinische Störungen der Schilddrüsenfunktion sind definiert als pathologische TSH-Konzentrationen bei asymptomatischen Patienten mit normalen peripheren Schilddrüsenhormonen. Die Prävalenz der subklinischen Hypothyreose (erhöhtes TSH) liegt zwischen 2.5 bis 15%, sie kann mit Allgemeinsymptomen und einer Dyslipidämie assoziiert sein. Eine Substitution wird in der Regel erst ab einem TSH von > 10 µU/l empfohlen und sollte mit einem reinen T4-Präparat durchgeführt werden. Bei tieferen TSH-Werten richtet sich die Indikation nach zusätzlichen Risikofaktoren und Symptomen. Die subklinische Hyperthyreose (supprimiertes TSH) ist mit einer erhöhten kardialen Morbidität und verminderter Knochendichte assoziiert, die Indikation zur Diagnostik und Therapie richtet sich individuell nach dem Risiko. Eine konsequente Jod-Prophylaxe mit Thyreostatika sollte bei Exposition mit Röntgenkontrastmitteln durchgeführt werden.
Ross Sea polynyas: Response of ice concentration retrievals to large areas of thin ice
Authors: Kwok R. , Comiso J. C. , Martin S. , Drucker R.
Published: December 2007

For a 3‐month period between May and July of 2005, we examine the response of the Advanced Microwave Scanning Radiometer (AMSR‐E) Enhanced NASA Team 2 (NT2) and AMSR‐E Bootstrap (ABA) ice concentration algorithms to large areas of thin ice of the Ross Sea polynyas. Coincident Envisat Synthetic Aperture Radar (SAR) coverage of the region during this period offers a detailed look at the development of the polynyas within several hundred kilometers of the ice front. The high‐resolution imagery and derived ice motion fields show bands of polynya ice, covering up to ∼105 km2 of the Ross Sea, that are associated with wind‐forced advection. In this study, ice thickness from AMSR‐E 36 GHz polarization information serves as the basis for examination of the response. The quality of the thickness of newly formed sea ice (<10 cm) from AMSR‐E is first assessed with thickness estimates derived from ice surface temperatures from the Moderate Resolution Imaging Spectroradiometer (MODIS) instrument. The effect of large areas of thin ice in lowering the ice concentration estimates from both NT2/ABA approaches is clearly demonstrated. Results show relatively robust relationships between retrieved ice concentrations and thin ice thickness estimates that differ between the two algorithms. These relationships define the approximate spatial coincidence of ice concentration and thickness isopleths. Using the 83% (ABA) and 91% (NT2) isopleths as polynya boundaries, we show that the computed coverage compares well with that using the estimated 10‐cm thickness contour. The thin ice response characterized here suggests that in regions with polynyas, the retrieval results could be used to provide useful geophysical information, namely thickness and coverage.
Variations of the seasonal sea level cycle in southern Europe
Authors: Marcos M. , Tsimplis M. N.
Published: December 2007

The temporal and spatial variability of the seasonal signals in the Mediterranean Sea and the Atlantic Iberian coast is explored on the basis of tide gauge data. Mean amplitudes range in the various stations between 3 and 7 cm for the mean annual component and between 1 and 3 cm for the semiannual component. On average, seasonal signals account for approximately 20% of the total variance of monthly records. The seasonal cycle is unsteady in time, with large variations in amplitudes and phases in some stations reaching up to 8 cm and 40 d, respectively. The contribution of the direct atmospheric effects to the seasonal cycle has been estimated by means of the output of a barotropic model forced with wind and atmospheric pressure. This contribution is regionally coherent, albeit variable in time. The annual cycle of the residuals (observations minus atmospherically induced sea level) is larger than that of the observations by about 2–3 cm. The residual semiannual cycle is smaller than that of the observations by about 25%. The temporal variability of the seasonal cycle of the residual series is also explored. Changes in water temperatures at the upper layers is the only parameter that appears connected with the observed variations.
Centennial scale climate instabilities in a wet early Holocene West African monsoon
Authors: Weldeab Syee , Lea David W. , Schneider Ralph R. , Andersen Nils
Published: December 2007

A Holocene Gulf of Guinea record of riverine runoff, based on Ba/Ca in tests of a shallow‐dwelling planktic foraminifer, and sea surface temperature (SST), based on Mg/Ca, reveals centennial‐scale instabilities in West African monsoon (WAM) precipitation and eastern equatorial Atlantic (EEA) thermal conditions. The long‐term Holocene climate trend is characterized by a warm and wet early‐mid Holocene and gradual drying and cooling during the late Holocene. Superimposed on this trend are numerous centennial scale drops in precipitation during the early‐mid Holocene. The greatest declines in early Holocene monsoon precipitation were accompanied by significant SST cooling in the EEA and correlate with drops in air temperature over Greenland and fresh water outbursts into the North Atlantic (NA). This observation suggests that early Holocene climate instabilities in the NA were closely linked to changes in the WAM. The strong imprint of NA events in summer monsoon precipitation suggests that these events were not confined to winter‐time. The late Holocene does not show large amplitude changes in riverine runoff at the centennial level. The relatively stable late Holocene conditions likely reflect a weakening and stabilization of the monsoon system, probably due to diminished influence of the NA region due to a reduction in ice sheet.
Incorporating plant functional diversity effects in ecosystem service assessments
Authors: Díaz Sandra , Lavorel Sandra , de Bello Francesco , Quétier Fabien , Grigulis Karl , Robson T. Matthew
Published: December 2007

Global environmental change affects the sustained provision of a wide set of ecosystem services. Although the delivery of ecosystem services is strongly affected by abiotic drivers and direct land use effects, it is also modulated by the functional diversity of biological communities (the value, range, and relative abundance of functional traits in a given ecosystem). The focus of this article is on integrating the different possible mechanisms by which functional diversity affects ecosystem properties that are directly relevant to ecosystem services. We propose a systematic way for progressing in understanding how land cover change affects these ecosystem properties through functional diversity modifications. Models on links between ecosystem properties and the local mean, range, and distribution of plant trait values are numerous, but they have been scattered in the literature, with varying degrees of empirical support and varying functional diversity components analyzed. Here we articulate these different components in a single conceptual and methodological framework that allows testing them in combination. We illustrate our approach with examples from the literature and apply the proposed framework to a grassland system in the central French Alps in which functional diversity, by responding to land use change, alters the provision of ecosystem services important to local stakeholders. We claim that our framework contributes to opening a new area of research at the interface of land change science and fundamental ecology.
The evolution of urban sprawl: Evidence of spatial heterogeneity and increasing land fragmentation
Authors: Irwin Elena G. , Bockstael Nancy E.
Published: December 2007

We investigate the dynamics and spatial distribution of land use fragmentation in a rapidly urbanizing region of the United States to test key propositions regarding the evolution of sprawl. Using selected pattern metrics and data from 1973 and 2000 for the state of Maryland, we find significant increases in developed and undeveloped land fragmentation but substantial spatial heterogeneity as well. Estimated fragmentation gradients that describe mean fragmentation as a function of distance from urban centers confirm the hypotheses that fragmentation rises and falls with distance and that the point of maximum fragmentation shifted outward over time. However, rather than outward increases in sprawl balanced by development infill, we find substantial and significant increases in mean fragmentation values along the entire urban–rural gradient. These findings are in contrast to the results of Burchfieldet al.[Burchfield M, Overman HG, Puga D, Turner MA (2006)Q J Econ121:587–633], who conclude that the extent of sprawl remained roughly unchanged in the Unites States between 1976 and 1992. As demonstrated here, both the data and pattern measure used in their study are systematically biased against recording low-density residential development, the very land use that we find is most strongly associated with fragmentation. Other results demonstrate the association between exurban growth and increasing fragmentation and the systematic variation of fragmentation with nonurban factors. In particular, proximity to the Chesapeake Bay is negatively associated with fragmentation, suggesting that an attraction effect associated with this natural amenity has concentrated development.
Evidence for a vascular contribution to diffusion FMRI at high
b
value
Authors: Miller Karla L. , Bulte Daniel P. , Devlin Hannah , Robson Matthew D. , Wise Richard G. , Woolrich Mark W. , Jezzard Peter , Behrens Timothy E. J.
Published: December 2007

Recent work has suggested that diffusion-weighted functional magnetic resonance imaging (FMRI) with strong diffusion weighting (high
b
value) detects neuronal swelling that is directly related to neuronal firing. This would constitute a much more direct measure of brain activity than current methods and represent a major advance in neuroimaging. However, it has not been firmly established that the observed signal changes do not reflect residual vascular effects, which are known to exist at low
b
value. This study measures the vascular component of diffusion FMRI directly by using hypercapnia, which induces blood flow changes in the absence of a change in neuronal firing. Hypercapnia elicits a similar diffusion FMRI response to a visual stimulus including a rise in percent signal change with increasing
b
value, which was reported for visual activation. Analysis of the response timing found no evidence for an early response at high
b
value, which has been reported as evidence for a nonhemodynamic response. These results suggest that a large component of the diffusion FMRI signal at high
b
value is vascular rather than neuronal.
Selection of mammalian cells based on their cell-cycle phase using dielectrophoresis
Authors: Kim Unyoung , Shu Chih-Wen , Dane Karen Y. , Daugherty Patrick S. , Wang Jean Y. J. , Soh H. T.
Published: December 2007

An effective, noninvasive means of selecting cells based on their phase within the cell cycle is an important capability for biological research. Current methods of producing synchronous cell populations, however, tend to disrupt the natural physiology of the cell or suffer from low synchronization yields. In this work, we report a microfluidic device that utilizes the dielectrophoresis phenomenon to synchronize cells by exploiting the relationship between the cell's volume and its phase in the cell cycle. The dielectrophoresis activated cell synchronizer (DACSync) device accepts an asynchronous mixture of cells at the inlet, fractionates the cell populations according to the cell-cycle phase (G
1
/S and G
2
/M), and elutes them through different outlets. The device is gentle and efficient; it utilizes electric fields that are 1–2 orders of magnitude below those used in electroporation and enriches asynchronous tumor cells in the G
1
phase to 96% in one round of sorting, in a continuous flow manner at a throughput of 2 × 10
5
cells per hour per microchannel. This work illustrates the feasibility of using laminar flow and electrokinetic forces for the efficient, noninvasive separation of living cells.
Therapeutic B cell depletion impairs adaptive and autoreactive CD4+T cell activation in mice
Authors: Bouaziz Jean-David , Yanaba Koichi , Venturi Guglielmo M. , Wang Yaming , Tisch Roland M. , Poe Jonathan C. , Tedder Thomas F.
Published: December 2007

CD20 antibody depletion of B lymphocytes effectively ameliorates multiple T cell-mediated autoimmune diseases through mechanisms that remain unclear. To address this, a mouse CD20 antibody that depletes >95% of mature B cells in mice with otherwise intact immune systems was used to assess the role of B cells in CD4+and CD8+T cell activation and expansionin vivo. B cell depletion had no direct effect on T cell subsets or the activation status of CD4+and CD8+T cells in naive mice. However, B cell depletion impaired CD4+T cell activation and clonal expansion in response to protein antigens and pathogen challenge, whereas CD8+T cell activation was not affected.In vivodendritic cell ablation, along with CD20 immunotherapy, revealed that optimal antigen-specific CD4+T cell priming required both B cells and dendritic cells. Most importantly, B cell depletion inhibited antigen-specific CD4+T cell expansion in both collagen-induced arthritis and autoimmune diabetes mouse models. These results provide direct evidence that B cells contribute to T cell activation and expansionin vivoand offer insights into the mechanism of action for B cell depletion therapy in the treatment of autoimmunity.
Salvage of Long-Term Central Venous Catheters During an Outbreak ofPseudomonas putidaandStenotrophomonas maltophiliaInfections Associated With Contaminated Heparin Catheter-Lock Solution
Authors: Dias M. Beatriz Souza , Habert Alina Bernardes , Borrasca Vera , Stempliuk Valeska , Ciolli Aina , Araújo M. Rita E. , Costa Silvia F. , Levin Anna S.
Published: December 2007

Objective.

To describe the management of patients with long-term central venous catheters (CVCs) during an outbreak of infection due toPseudomonas putidaandStenotrophomonas maltophiliaassociated with contaminated heparin catheter-lock solution.

Design.

Descriptive study.

Setting.

Private, 250-bed tertiary-care hospital.

Methods.

In March 2003, we identified 2 febrile cancer patients withP. putidabacteremia. Over 2 days, 7 cases of bacteremia were identified; lots of syringes prefilled with heparin catheter-lock solution, supplied by a compounding pharmacy, were recalled and samples were cultured. More cases of bacteremia appeared during the following days, and any patient who had had a catheter lock infused with the suspect solution was asked to provide blood samples for culture, even if the patient was asymptomatic. Isolates that were recovered from culture were typed by pulsed-field gel electrophoresis. Antimicrobial salvage treatment of long-term CVCs was attempted.

Results.

A total of 154 patients had had their catheter lock infused with solution from the lots that were suspected of being contaminated. Only 48 of these patients had CVCs. By day 7 of the outbreak, 18 of these patients had become symptomatic. Twenty-six of the remaining 30 asymptomatic patients then also provided blood samples for culture, 10 of whom developed fever shortly after samples were collected. Thirty-two patients were identified who hadP. putidabacteremia; 9 also had infection due toS. maltophilia. Samples from 1 of the 3 lots of prefilled syringes in use at the time of the outbreak also grewP. putidaon culture. Molecular typing identified 3 different clones ofP. putidafrom patients and heparin catheter-lock solution, and 1 clone ofS. maltophilia. A total of 27 patients received antimicrobial therapy regimens, some of which included decontamination of the catheter lock with anti-infective lock solution. Of 27 patients, 19 (70%) retained their long-term CVC during the 6-month follow-up period.

Conclusions.

To our knowledge, this is one of the largest prospective experiences in the management of bloodstream infection associated with long-term CVCs. The infections were caused by gram-negative bacilli and were managed without catheter removal, with a high response rate. We emphasize the risks of using intravenous formulations of medications supplied by compounding pharmacies that produce large quantities of drugs.
DYC-1, a Protein Functionally Linked to Dystrophin inCaenorhabditis elegansIs Associated with the Dense Body, Where It Interacts with the Muscle LIM Domain Protein ZYX-1
Authors: Lecroisey Claire , Martin Edwige , Mariol Marie-Christine , Granger Laure , Schwab Yannick , Labouesse Michel , Ségalat Laurent , Gieseler Kathrin
Published: December 2007

In Caenorhabditis elegans, mutations of the dystrophin homologue, dys-1, produce a peculiar behavioral phenotype (hyperactivity and a tendency to hypercontract). In a sensitized genetic background, dys-1 mutations also lead to muscle necrosis. The dyc-1 gene was previously identified in a genetic screen because its mutation leads to the same phenotype as dys-1, suggesting that the two genes are functionally linked. Here, we report the detailed characterization of the dyc-1 gene. dyc-1 encodes two isoforms, which are expressed in neurons and muscles. Isoform-specific RNAi experiments show that the absence of the muscle isoform, and not that of the neuronal isoform, is responsible for the dyc-1 mutant phenotype. In the sarcomere, the DYC-1 protein is localized at the edges of the dense body, the nematode muscle adhesion structure where actin filaments are anchored and linked to the sarcolemma. In yeast two-hybrid assays, DYC-1 interacts with ZYX-1, the homologue of the vertebrate focal adhesion LIM domain protein zyxin. ZYX-1 localizes at dense bodies and M-lines as well as in the nucleus of C. elegans striated muscles. The DYC-1 protein possesses a highly conserved 19 amino acid sequence, which is involved in the interaction with ZYX-1 and which is sufficient for addressing DYC-1 to the dense body. Altogether our findings indicate that DYC-1 may be involved in dense body function and stability. This, taken together with the functional link between the C. elegans DYC-1 and DYS-1 proteins, furthermore suggests a requirement of dystrophin function at this structure. As the dense body shares functional similarity with both the vertebrate Z-disk and the costamere, we therefore postulate that disruption of muscle cell adhesion structures might be the primary event of muscle degeneration occurring in the absence of dystrophin, in C. elegans as well as vertebrates.
A Lipid-mediated Quality Control Process in the Golgi Apparatus in Yeast
Authors: Pineau Ludovic , Bonifait Laetitia , Berjeaud Jean-Marc , Alimardani-Theuil Parissa , Bergès Thierry , Ferreira Thierry
Published: December 2007

When heme biosynthesis is disrupted, the yeast Saccharomyces cerevisiae becomes unable to synthesize its major sterol, ergosterol, and desaturate fatty acids. We took advantage of this physiological peculiarity to evaluate the consequences of ergosterol and/or unsaturated fatty acid (UFA) depletions on the biogenesis of a model polytopic plasma membrane protein, the uracil permease Fur4p. We show that under UFA shortage, which results in low amounts of diunsaturated phospholipid species, and under ergosterol depletion, Fur4p is prematurely routed from the Golgi apparatus to the vacuolar lumen in a process that requires the ubiquitin ligase Rsp5p. Interestingly, this diversion is not correlated to Fur4p exclusion from detergent-resistant membranes. In an independent set of experiments, we show that Fur4p targeting to the plasma membrane depends on phosphatidylethanolamine amounts and more specifically on the propensity of this phospholipid to form a hexagonal phase. In light of recent literature, we propose a model in which ergosterol and diunsaturated phospholipid species maintain optimal membrane curvature for Fur4p to evade the Golgi quality control process and to be properly delivered to its normal destination.