bluuebunny/crossref_metadata_2025 huggingface dataset:
THE SEQUENTIAL ESTIMATION OF SUBSET VAR WITH FORGETTING FACTOR AND INTERCEPT VARIABLE
Authors: O'NEILL T. J. , PENM J. H. W. , TERRELL R. D.
Published: November 2004

In this paper we propose a forward time update algorithm to recursively estimate subset vector autoregressive models (including an intercept term) with a forgetting factor, using the exact window case. The proposed recursions cover, for the first time, subset vector autoregressive models (VAR) with a forgetting factor and an intercept variable. We then present two applications. In the first application we apply the proposed estimation algorithm to the quarterly aluminium prices on the London Metal Exchange. The findings show that the proposed algorithm can improve the forecasting performance. In the second application a bivariate system investigates the relationship between the Australian's All Ordinaries Share Price Index (SPI) futures and BHP share price (BHP). The proposed algorithm also introduces the Monte Carlo Integration approach into the proposed algorithm to generate error bands for the impulse responses. These results confirm that the SPI Granger causes BHP, but not vice versa.
ENHANCING SYSTEM-WIDE PROFITABILITY WITH NEW PRODUCT INTRODUCTION AND THROUGHPUT ACCOUNTING
Authors: HILMOLA OLLI-PEKKA
Published: November 2004

Most often product development performance is used as an appraisal measure to achieve sustainable profitability now and in the future. Despite the fact that global markets are favoring more knowledge and service intensive products, manufacturing still has an important role within New Product Introduction (NPI) process. It is argued in this paper that the proper understanding and management of business decisions through manufacturing and market constraints is vital in the profitability evaluation of new product alternatives. According to the analyzed hypothetical example, conventional cost accounting methods in the evaluation process will lead to losses, where constraints management method (called throughput accounting) increases profits significantly. Despite this important finding, in the paper it is being speculated that global infinite market demand combined with higher number of possible product alternatives and keen management focus to concentrate only on the most profitable one might diminish profitability performance according to these two accounting approaches. However, according to the hypothetical example, in infinite global markets it seems to be extremely profitable to concentrate in several product groups simultaneously, instead of one.
REVOLUTIONARY INDUSTRIAL CHANGE IN AIR TRANSPORT — RESEARCH AND STRATEGIC APPLICATION
Authors: McGRATH ROBERT N.
Published: November 2004

This paper summarizes and interprets several years of research that considered the National Aeronautics and Space Administration's assertion that the Small Aircraft Transportation System (SATS) will become an economical alternative to automobile and airline travel — a radical paradigmatic shift. However, the literature suggests that revolutionary changes to major techno-economic paradigms should not always be made in singular radical disruptions, but rather, through the commercialization of technologies in series of market niches chosen wisely. Therefore, hypothetical SATS aircraft cost and technical performance characteristics were computer-modeled to simulate SATS in the corporate aviation environment, and in the air taxi industry. Results of exploratory research based on these models are reviewed. From the standpoint of traditional Strategic Management theory, implications are offered regarding the successful incubation of this emerging industry.
Rosuvastatin reduces experimental left ventricular infarct size after ischemia-reperfusion injury but not total coronary occlusion
Authors: Weinberg Ellen O. , Scherrer-Crosbie Marielle , Picard Michael H. , Nasseri Boris A. , MacGillivray Catherine , Gannon Joseph , Lian Qingyu , Bloch Kenneth D. , Lee Richard T.
Published: November 2004

This study compared the effects of rosuvastatin on left ventricular infarct size in mice after permanent coronary occlusion vs. 60 min of ischemia followed by 24 h of reperfusion. Statins can inhibit neutrophil adhesion, increase nitric oxide synthase (NOS) expression, and mobilize progenitor stem cells after ischemic injury. Mice received blinded and randomized administration of rosuvastatin (20 mg·kg−1·day−1) or saline from 2 days before surgery until death. After 60 min of ischemia with reperfusion, infarct size was reduced by 18% ( P = 0.03) in mice randomized to receive rosuvastatin ( n = 18) vs. saline ( n = 22) but was similar after permanent occlusion in rosuvastatin ( n = 17) and saline ( n = 20) groups ( P = not significant). Myocardial infarct size after permanent left anterior descending coronary artery occlusion ( n = 6) tended to be greater in NOS3-deficient mice than in the wild-type saline group (33 ± 4 vs. 23 ± 2%, P = 0.08). Infarct size in NOS3-deficient mice was not modified by treatment with rosuvastatin (34 ± 5%, n = 6, P = not significant vs. NOS3-deficient saline group). After 60 min of ischemia-reperfusion, neutrophil infiltration was similar in rosuvastatin and saline groups as was the percentage of CD34+, Sca-1+, and c-Kit+ cells. Left ventricular NOS3 mRNA and protein levels were unchanged by rosuvastatin. Rosuvastatin reduces infarct size after 60 min of ischemia-reperfusion but not after permanent coronary occlusion, suggesting a potential anti-inflammatory effect. Although we were unable to demonstrate that the myocardial protection was due to an effect on neutrophil infiltration, stem cell mobilization, or induction of NOS3, these data suggest that rosuvastatin may be particularly beneficial in myocardial protection after ischemia-reperfusion injury.
Oxygen transport by low and normal oxygen affinity hemoglobin vesicles in extreme hemodilution
Authors: Cabrales Pedro , Sakai Hiromi , Tsai Amy G. , Takeoka Shinji , Tsuchida Eishun , Intaglietta Marcos
Published: November 2004

The oxygen transport capacity of phospholipid vesicles encapsulating purified Hb (HbV) produced with a Po2at which Hb is 50% saturated (P 50 ) of 8 (HbV8) and 29 mmHg (HbV29) was investigated in the hamster chamber window model by using microvascular measurements to determine oxygen delivery during extreme hemodilution. Two isovolemic hemodilution steps were performed with 5% recombinant albumin (rHSA) until Hct was 35% of baseline. Isovolemic exchange was continued using HbV suspended in rHSA solution to a total [Hb] of 5.7 g/dl in blood. P50was modified by coencapsulating pyridoxal 5′-phosphate. Final Hct was 11% for the HbV groups, with a plasma [Hb] of 2.1 ± 0.1 g/dl after exchange with HbV8or HbV29. A reference group was hemodiluted to Hct 11% with only rHSA. All groups showed stable blood pressure and heart rate. Arterial oxygen tensions were significantly higher than baseline for the HbV groups and the rHSA group and significantly lower for the HbV groups compared with the rHSA group. Blood pressure was significantly higher for the HbV8group compared with the HbV29group. Arteriolar and venular blood flows were significantly higher than baseline for the HbV groups. Microvascular oxygen delivery and extraction were similar for the HbV groups but lower for the rHSA group ( P < 0.05). Venular and tissue Po2were statistically higher for the HbV8vs. the HbV29and rHSA groups ( P < 0.05). Improved tissue Po2is obtained when red blood cells deliver oxygen in combination with a high- rather than low-affinity oxygen carrier.
Myocardial hibernation: a delicate balance
Authors: Heusch Gerd , Schulz Rainer , Rahimtoola Shahbudin H.
Published: November 2004

The pathophysiology of myocardial hibernation is characterized as a situation of reduced regional contractile function distal to a coronary artery stenosis that recovers after removal of the coronary stenosis. A subacute “downregulation” of contractile function in response to reduced regional myocardial blood flow exists, which normalizes regional energy and substrate metabolism but does not persist for more than 12–24 h. Chronic hibernation develops in response to one or more episodes of myocardial ischemia-reperfusion, possibly progressing from repetitive stunning with normal blood flow to hibernation with reduced blood flow. An upregulation of a protective gene program is seen in hibernating myocardium, putting it into the context of preconditioning. The morphology of hibernating myocardium is characterized by both adaptive and degenerative features.
Hypoxic postconditioning reduces cardiomyocyte loss by inhibiting ROS generation and intracellular Ca2+ overload
Authors: Sun He-Ying , Wang Ning-Ping , Kerendi Faraz , Halkos Michael , Kin Hajime , Guyton Robert A. , Vinten-Johansen Jakob , Zhao Zhi-Qing
Published: November 2004

We have shown that intermittent interruption of immediate reflow at reperfusion (i.e., postconditioning) reduces infarct size in in vivo models after ischemia. Cardioprotection of postconditioning has been associated with attenuation of neutrophil-related events. However, it is unknown whether postconditioning before reoxygenation after hypoxia in cultured cardiomyocytes in the absence of neutrophils confers protection. This study tested the hypothesis that prevention of cardiomyocyte damage by hypoxic postconditioning (Postcon) is associated with a reduction in the generation of reactive oxygen species (ROS) and intracellular Ca2+ overload. Primary cultured neonatal rat cardiomyocytes were exposed to 3 h of hypoxia followed by 6 h of reoxygenation. Cardiomyocytes were postconditioned after the 3-h index hypoxia by three cycles of 5 min of reoxygenation and 5 min of rehypoxia applied before 6 h of reoxygenation. Relative to sham control and hypoxia alone, the generation of ROS (increased lucigenin-enhanced chemiluminescence, SOD-inhibitable cytochrome c reduction, and generation of hydrogen peroxide) was significantly augmented after immediate reoxygenation as was the production of malondialdehyde, a product of lipid peroxidation. Concomitant with these changes, intracellular and mitochondrial Ca2+ concentrations, which were detected by fluorescent fluo-4 AM and X-rhod-1 AM staining, respectively, were elevated. Cell viability assessed by propidium iodide staining was decreased consistent with increased levels of lactate dehydrogenase after reoxygenation. Postcon treatment at the onset of reoxygenation reduced ROS generation and malondialdehyde concentration in media and attenuated cardiomyocyte death assessed by propidium iodide and lactate dehydrogenase. Postcon treatment was associated with a decrease in intracellular and mitochondrial Ca2+ concentrations. These data suggest that Postcon treatment reduces reoxygenation-induced injury in cardiomyocytes and is potentially mediated by attenuation of ROS generation, lipid peroxidation, and intracellular and mitochondrial Ca2+ overload.
Mitochondrial DNA damage triggers mitochondrial dysfunction and apoptosis in oxidant-challenged lung endothelial cells
Authors: Ruchko Mykhaylo , Gorodnya Olena , LeDoux Susan P. , Alexeyev Mikhail F. , Al-Mehdi Abu-Bakr , Gillespie Mark N.
Published: November 2004

Oxidant-induced death and dysfunction of pulmonary vascular cells play important roles in the evolution of acute lung injury. In pulmonary artery endothelial cells (PAECs), oxidant-mediated damage to mitochondrial DNA (mtDNA) seems to be critical in initiating cytotoxicity inasmuch as overexpression of the mitochondrially targeted human DNA repair enzyme, human Ogg1 (hOgg1), prevents both mtDNA damage and cell death (Dobson AW, Grishko V, LeDoux SP, Kelley MR, Wilson GL, and Gillespie MN. Am J Physiol Lung Cell Mol Physiol 283: L205–L210, 2002). The mechanism by which mtDNA damage leads to PAEC death is unknown, and the present study tested the specific hypothesis that enhanced mtDNA repair suppresses PAEC mitochondrial dysfunction and apoptosis evoked by xanthine oxidase (XO). PAECs transfected either with an adenoviral vector encoding hOgg1 linked to a mitochondrial targeting sequence or with empty vector were challenged with ascending doses of XO plus hypoxanthine. Quantitative Southern blot analyses revealed that, as expected, hOgg1 overexpression suppressed XO-induced mtDNA damage. Mitochondrial overexpression of hOgg1 also suppressed the XO-mediated loss of mitochondrial membrane potential. Importantly, hOgg1 overexpression attenuated XO-induced apoptosis as detected by suppression of caspase-3 activation, by reduced DNA fragmentation, and by a blunted appearance of condensed, fragmented nuclei. These observations suggest that mtDNA damage serves as a trigger for mitochondrial dysfunction and apoptosis in XO-treated PAECs.
Mechanisms of blood pressure variability-induced cardiac hypertrophy and dysfunction in mice with impaired baroreflex
Authors: Martinka Peter , Fielitz Jens , Patzak Andreas , Regitz-Zagrosek Vera , Persson Pontus B. , Stauss Harald M.
Published: November 2004

Enhanced blood pressure variability contributes to left ventricular hypertrophy and end-organ damage, even in the absence of hypertension. We hypothesized that the greater number of high-blood pressure episodes associated with enhanced blood pressure variability causes cardiac hypertrophy and dysfunction by activation of mechanosensitive and autocrine pathways. Normotensive mice were subjected to sinoaortic baroreceptor denervation (SAD) or sham surgery. Twelve weeks later, blood pressure variability was doubled in SAD compared with sham-operated mice. Blood pressure did not differ. Cardiac hypertrophy was reflected in greater heart/body weight ratios, larger myocyte cross-sectional areas, and greater left ventricular collagen deposition. Furthermore, left ventricular atrial and brain natriuretic peptide mRNA expression was greater in SAD than in sham-operated mice. SAD had higher left ventricular end-diastolic pressures and lower myocardial contractility indexes, indicating cardiac dysfunction. Cardiac protein content of phosphorylated p125 focal adhesion kinase (p125 FAK) and phosphorylated p38 mitogen-activated protein kinase (p38 MAPK) was greater in SAD than in sham-operated mice, indicating activation of mechanosensitive pathways of cardiac hypertrophy. Furthermore, enhanced cardiac renin and transforming growth factor-β1 (TGFbeta1) protein content indicates activation of autocrine pathways of cardiac hypertrophy. Adrenal tyrosine hydroxylase protein content and the number of renin-positive glomeruli were not different, suggesting that sympathetic activation and the systemic renin-angiotensin system did not contribute to cardiac hypertrophy. In conclusion, more frequent blood pressure rises in subjects with high blood pressure variability activate mechanosensitive and autocrine pathways leading to cardiac hypertrophy and dysfunction even in the absence of hypertension.
Nonresponsiveness of cerebral p53-MDM2 functional circuit in newborn rat pups rendered IUGR via uteroplacental insufficiency
Authors: Ke Xingrao , McKnight Robert A. , Wang Zheng-ming , Yu Xing , Wang Laiyi , Callaway Christopher W. , Albertine Kurt H. , Lane Robert H.
Published: November 2004

Severe uteroplacental insufficiency causes cerebral apoptosis in the fetus. Moderate uteroplacental insufficiency causes intrauterine growth retardation (IUGR) and increases the risk of postnatal neurological morbidity. In the rat, uteroplacental insufficiency and IUGR affect cerebral gene expression of Bcl-2 and predispose the newborn IUGR rat toward cerebral apoptosis when challenged with perinatal hypoxia. Expression of Bcl-2, as well as the proapoptotic protein Bax, is regulated by p53. p53 also induces MDM2 transcription, which functions to limit further p53-induced apoptosis. The predisposition of the IUGR fetus toward cerebral apoptosis suggests that the p53-MDM2 “functional” circuit may be perturbed in the newborn IUGR rat brain. We hypothesized that MDM2 cerebral expression does not increase in response to increased p53 expression or increased levels of phospho-p53 (Ser15), an activated form of p53. To prove this hypothesis, we induced IUGR through bilateral uterine ligation of the pregnant rat. Uteroplacental insufficiency significantly increased p53 mRNA, total p53 protein, and phospho-p53 (Ser15) protein levels in the brain at term. Increased expression of phospho-p53 (Ser15) and terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling-positive cells were localized to the CA1 region of the hippocampus, the subcortical and periventricular white matter, and the amygdala of the IUGR rat brain. In contrast, uteroplacental insufficiency decreased cerebral MDM2 mRNA and phospho-MDM2 (Ser166) protein levels in the IUGR rat pups. We conclude that the cerebral MDM2 response to increased p53 expression is not present in the newborn IUGR rat pup, and we speculate that this contributes to the predisposition of the IUGR fetus toward perinatal and long-term neurodevelopmental morbidities.
Agonist-dependent variablity of contributions of nitric oxide and prostaglandins in human skeletal muscle
Authors: Schrage William G. , Dietz Niki M. , Eisenach John H. , Joyner Michael J.
Published: November 2004

The relative contributions of endothelium-dependent dilators [nitric oxide (NO), prostaglandins (PGs), and endothelium-derived hyperpolarizing factor (EDHF)] in human limbs are poorly understood. We tested the hypothesis that relative contributions of NO and PGs differ between endothelial agonists acetylcholine (ACh; 1, 2, and 4 μg·dl−1·min−1) and bradykinin (BK; 6.25, 25, and 50 ng·dl−1·min−1). We measured forearm blood flow (FBF) using venous occlusion plethysmography in 50 healthy volunteers (27 ± 1 yr) in response to brachial artery infusion of ACh or BK in the absence and presence of inhibitors of NO synthase [NOS; with NG-monomethyl-l-arginine (l-NMMA)] and cyclooxygenase (COX; with ketorolac). Furthermore, we tested the idea that the NOS + COX-independent dilation (in the presence of l-NMMA + ketorolac, presumably EDHF) could be inhibited by exogenous NO administration, as reported in animal studies. FBF increased ∼10-fold in the ACh control; l-NMMA reduced baseline FBF and ACh dilation, whereas addition of ketorolac had no further effect. Ketorolac alone did not alter ACh dilation, but addition of l-NMMA reduced ACh dilation significantly. For BK infusion, FBF increased ∼10-fold in the control condition; l-NMMA tended to reduce BK dilation ( P < 0.1), and addition of ketorolac significantly reduced BK dilation. Similar to ACh, ketorolac alone did not alter BK dilation, but addition of l-NMMA reduced BK dilation. To test the idea that NO can inhibit the NOS + COX-independent portion of dilation, we infused a dose of sodium nitroprusside (NO-clamp technique) during ACh or BK that restored the reduction in baseline blood flow due to l-NMMA. Regardless of treatment order, the NO clamp restored baseline FBF but did not reduce the NOS + COX-independent dilation to ACh or BK. We conclude that the contribution of NO and PGs differs between ACh and BK, with ACh being more dependent on NO and BK being mostly dependent on a NOS + COX-independent mechanism (EDHF) in healthy young adults. The NOS + COX-independent dilation does not appear sensitive to feedback inhibition from NO in the human forearm.
Heterogeneous Integration of Bilateral Whisker Signals by Neurons in Primary Somatosensory Cortex of Awake Rats
Authors: Wiest Michael C. , Bentley Nick , Nicolelis Miguel A. L.
Published: November 2004

Bilateral single-unit recordings in primary somatosensory cortex (S1) of anesthetized rats have revealed substantial cross talk between cortical hemispheres, suggesting the possibility that behaviorally relevant bilateral integration could occur in S1. To determine the extent of bilateral neural responses in awake animals, we recorded S1 multi- and single-unit activity in head-immobilized rats while stimulating groups of 4 whiskers from the same column on both sides of the head. Results from these experiments confirm the widespread presence of single units responding to tactile stimuli on either side of the face in S1 of awake animals. Quantification of bilateral integration by multiunits revealed both facilitative and suppressive integration of bilateral inputs. Varying the interval between left and right whisker stimuli between 0 and 120 ms showed the temporal integration of bilateral stimuli to be dominated on average by suppression at intervals around 30 ms, in agreement with comparable recordings in anesthetized animals. Contrary to the anesthetized data, in the awake animals we observed a high level of heterogeneity of bilateral responses and a strong interaction between synchronous bilateral stimuli. The results challenge the traditional conception of highly segregated hemispheric processing channels in the rat S1 cortex, and support the hypothesis that callosal cross-projections between the two hemispheres mediate rats' known ability to integrate bilateral whisker signals.
Intricacies of Collins' Parsing Model
Authors: Bikel Daniel M.
Published: November 2004

This article documents a large set of heretofore unpublished details Collins used in his parser, such that, along with Collins' (1999) thesis, this article contains all information necessary to duplicate Collins' benchmark results. Indeed, these as-yet-unpublished details account for an 11% relative increase in error from an implementation including all details to a clean-room implementation of Collins' model. We also show a cleaner and equally well-performing method for the handling of punctuation and conjunction and reveal certain other probabilistic oddities about Collins' parser. We not only analyze the effect of the unpublished details, but also reanalyze the effect of certain well-known details, revealing that bilexical dependencies are barely used by the model and that head choice is not nearly as important to overall parsing performance as once thought. Finally, we perform experiments that show that the true discriminative power of lexicalization appears to lie in the fact that unlexicalized syntactic structures are generated conditioning on the headword and its part of speech.
Nonlinear and Noisy Extension of Independent Component Analysis: Theory and Its Application to a Pitch Sensation Model
Authors: Maeda Shin-ichi , Song Wen-Jie , Ishii Shin
Published: November 2004

In this letter, we propose a noisy nonlinear version of independent component analysis (ICA). Assuming that the probability density function (p.d.f.) of sources is known, a learning rule is derived based on maximum likelihood estimation (MLE). Our model involves some algorithms of noisy linear ICA (e.g., Bermond & Cardoso, 1999) or noise-free nonlinear ICA (e.g., Lee, Koehler, & Orglmeister, 1997) as special cases. Especially when the nonlinear function is linear, the learning rule derived as a generalized expectation-maximization algorithm has a similar form to the noisy ICA algorithm previously presented by Douglas, Cichocki, and Amari (1998). Moreover, our learning rule becomes identical to the standard noise-free linear ICA algorithm in the noiseless limit, while existing MLE-based noisy ICA algorithms do not rigorously include the noise-free ICA.

We trained our noisy nonlinear ICA by using acoustic signals such as speech and music. The model after learning successfully simulates virtual pitch phenomena, and the existence region of virtual pitch is qualitatively similar to that observed in a psychoacoustic experiment. Although a linear transformation hypothesized in the central auditory system can account for the pitch sensation, our model suggests that the linear transformation can be acquired through learning from actual acoustic signals. Since our model includes a cepstrum analysis in a special case, it is expected to provide a useful feature extraction method that has often been given by the cepstrum analysis.
Postural Responses to Two Technologies for Generating Optical Flow
Authors: Stoffregen Thomas A. , Bardy Benoît G. , Merhi Omar A. , Oullier Olivier
Published: November 2004

The perception and control of stance are frequently studied in virtual environments, where computer-generated videographic displays are used to simulate the optical consequences of body sway. Generally, the intent of such studies is to understand how posture is controlled outside of virtual environments (i.e., in daily life). Accordingly, the validity of such studies will depend upon the extent to which postural responses to videographically generated optical flow resemble postural responses to optical flow that is generated in other ways. We conducted a direct test of postural responses to optical flow generated using two technologies: physical displacement of the visible surroundings (using a moving room), and videographic projection of computer-generated graphics. We attempted to make the two displays as similar as possible in terms of visual angle, optical texture, and the amplitude and frequency of oscillation. The results revealed several significant differences in postural responses to the two types of stimuli. This raises questions about the extent to which postural control in virtual environments can be generalized to postural control in the real world.
An Independent Visual Background Reduced Simulator Sickness in a Driving Simulator
Authors: Duh Henry Been-Lirn , Parker Donald E. , Furness Thomas A.
Published: November 2004

Simulator sickness (SS)-virtual environment (VE) sickness is expected to become increasingly troublesome as VE technology evolves. This paper investigated using an independent visual background (IVB) to reduce SS and VE sickness. The IVB is a visual scene component that provides visual motion and orientation cues that match those from the vestibular receptors. In this study, the IVB was stationary, fixed with respect to inertial space. Two experiments were conducted. The first experiment examined the differences in visual motion-induced postural disturbance as a function of simultaneous exposure to an IVB. Subjects exhibited less balance disturbance when the IVB was presented. An expected statistically significant interaction between IVB presence-absence and visual scene motion oscillation frequency was observed. In the second experiment, subjects reported less SS when the IVB was presented during the VE exposure. We suggest that an IVB may alleviate disturbance when conflicting visual and inertial cues evoke SS.
Preservation of Eumelanin Hair Pigmentation in Proopiomelanocortin-Deficient Mice on a Nonagouti (a/a) Genetic Background
Authors: Slominski Andrzej , Plonka Przemyslaw M. , Pisarchik Alexander , Smart James L. , Tolle Virginie , Wortsman Jacobo , Low Malcolm J.
Published: November 2004

The original strain of proopiomelanocortin (POMC)-deficient mice (Pomc−/−) was generated by homologous recombination in 129X1/SvJ (Aw/Aw)-derived embryonic stem cells using a targeting construct that deleted exon 3, encoding all the known functional POMC-derived peptides including αMSH, from the Pomc gene. Although these Pomc−/− mice exhibited adrenal hypoplasia and obesity similar to the syndrome of POMC deficiency in children, their agouti coat color was only subtly altered. To further investigate the mechanism of hair pigmentation in the absence of POMC peptides, we studied wild-type (Pomc+/+), heterozygous (Pomc+/−), and homozygous (Pomc−/−) mice on a nonagouti (a/a) 129;B6 hybrid genetic background. All three genotypes had similar black fur pigmentation with yellow hairs behind the ears, around the nipples, and in the perianal area characteristic of inbred C57BL/6 mice. Histologic and electron paramagnetic resonance spectrometry examination demonstrated that hair follicles in back skin of Pomc−/− mice developed with normal structure and eumelanin pigmentation; corresponding molecular analyses, however, excluded local production of αMSH and ACTH because neither Pomc nor putative Pomc pseudogene mRNAs were detected in the skin. Thus, 129;B6 Pomc null mutant mice produce abundant eumelanin hair pigmentation despite their congenital absence of melanocortin ligands. These results suggest that either the mouse melanocortin receptor 1 has sufficient basal activity to trigger and sustain eumelanogenesis in vivo or that redundant nonmelanocortin pathway(s) compensate for the melanocortin deficiency. Whereas the latter implies feedback control of melanogenesis, it is also possible that the two mechanisms operate jointly in hair follicles.
Ghrelin Is Produced by the Human Erythroleukemic HEL Cell Line and Involved in an Autocrine Pathway Leading to Cell Proliferation
Authors: De Vriese Carine , Grégoire Françoise , De Neef Philippe , Robberecht Patrick , Delporte Christine
Published: November 2004

Ghrelin, a ligand of the GH secretagogue receptor (GHS-R 1a), is a 28-amino acid peptide with an unusual octanoyl group on Ser3, crucial for its biological activity. For the first time, ghrelin and GHS-R 1b, a truncated variant of the receptor resulting from alternative splicing, but not GHS-R 1a, mRNAs were detected in the human erythroleukemic cell line HEL. Two antibodies, used for RIA, were directed against octanoylated and total (octanoylated and desoctanoylated) ghrelin, and the recognized epitopes were characterized. Using reverse phase HPLC analysis followed by RIA, we demonstrated that octanoylated and desoctanoylated ghrelins were present in HEL cells and their culture medium, of which more than 90% was octanoylated. The ghrelin levels were not affected after 24 h treatment with sodium butyrate, phorbol 12-myristate 13-acetate, or forskolin, but a significant 3-fold increase in desoctanoylated ghrelin was detected in the culture medium after 48 h treatment with sodium butyrate. The antighrelin SB801 and SB969 antisera inhibited HEL cell proliferation by 24% and 39%, respectively, after 72 h. Taken together, these data suggested that endogenous ghrelin stimulated HEL cell proliferation by an autocrine pathway involving an unidentified receptor, distinct from GHS-R1a, and that the HEL cell line represents a unique model to study the octanoylation of ghrelin.
Functional analyses oftiptopandAntennapediain the embryonic development ofOncopeltus fasciatussuggests an evolutionary pathway from ground state to insect legs
Authors: Herke Scott W. , Serio Nahum V. , Rogers Bryan T.
Published: November 2004

In insects, selector genes are thought to modify the development of a default, or `ground state', appendage into a tagma-specific appendage such as a mouthpart, antenna or leg. In the best described example, Drosophila melanogaster, the primary determination of leg identity is thought to result from regulatory interactions between the Hox genes and the antennal-specifying gene homothorax. Based on RNA-interference, a functional analysis of the selector gene tiptop and the Hox gene Antennapedia in Oncopeltus fasciatus embryogenesis is presented. It is shown that, in O. fasciatus, tiptop is required for the segmentation of distal leg segments and is required to specify the identity of the leg. The distal portions of legs with reduced tiptopdevelop like antennae. Thus, tiptop can act as a regulatory switch that chooses between antennal and leg identity. By contrast, Antennapedia does not act as a switch between leg and antennal identity. This observation suggests a significant difference in the mechanism of leg specification between O. fasciatus and D. melanogaster. These observations also suggest a significant plasticity in the mechanism of leg specification during insect evolution that is greater than would have been expected based on strictly morphological or molecular comparisons. Finally, it is proposed that a tiptop-like activity is a likely component of an ancestral leg specification mechanism. Incorporating a tiptop-like activity into a model of the leg-specification mechanism explains several mutant phenotypes, previously described in D. melanogaster, and suggests a mechanism for the evolution of legs from a ground state.
Hydraulic Conductivity and Cation Exchange in Non-prehydrated And Prehydrated Bentonite Permeated with Weak Inorganic Salt Solutions
Authors: Jo Ho Young , Benson Craig H. , Edil Tuncer B.
Published: November 2004

Sets of replicate hydraulic conductivity tests were conducted using 100 mM KCl and 20 and 40 mM CaCl2solutions to evaluate how changes in hydraulic conductivity are related to changes in the exchange complex and physical properties (water content and free swell) of prehydrated and non-prehydrated bentonite used for geosynthetic clay liners (GCLs). Essentially no change in hydraulic conductivity and water content (or void ratio) occurred during tests with the 100 mM KCl solution even though K+was replacing Na+on the exchange complex. In contrast, for the CaCl2solutions (20 mM and 40 mM), the hydraulic conductivity increased and the free swell and water content decreased as exchange of Ca2+for Na+occurred. Faster changes in hydraulic conductivity and the exchange complex occurred in the tests with the 40 mM CaCl2solution and the non-prehydrated bentonite (i.e.the hydraulic conductivity changed more rapidly when exchange occurred more rapidly). Even though exchange of Ca2+for Na+was essentially complete at the end of testing, the hydraulic conductivity obtained with the 20 mM CaCl2solution was less and the water content greater than obtained with the 40 mM CaCl2solution (2.6 × 10−8cm/svs.6.7 × 10−8cm/s, 122%vs.111%, and 3.2vs.2.9). Similarly, the prehydrated bentonite had lower hydraulic conductivity (1.9 × 10−8cm/svs.6.7 × 10−8cm/s) and greater water content (167%vs.111%) than the non-prehydrated bentonite at the end of testing, even though Ca-for-Na exchange was essentially complete.
Green Earth Pigment from the Kadaň Region, Czech Republic: Use of Rare Fe-rich Smectite
Authors: Hradil David , Grygar Tomáš , Hrušková Michaela , Bezdička Petr , Lang Kamil , Schneeweiss Oldřich , Chvátal Marek
Published: November 2004

A collection of green earths belonging to traditional artists’ pigments was examined in terms of mineralogy and provenance. The studied specimens included both mineralogical reference compounds and selected commercially available artists’ pigments, and contained green micas (glauconite or celadonite), chlorite, or smectite as pigmenting agents. The samples were examined by X-ray diffraction, Mössbauer spectroscopy, infrared (IR) spectroscopy, ultraviolet-visible (UV-Vis)-near-IR diffuse-reflectance spectroscopy and voltammetry of microparticles. Particular attention was paid to the Kadaň green earth, mined until the 20th century in the West Bohemia deposit. The Greene-Kelly charge-reduction test, detailed description of non-basal diffraction patterns and characteristic vibrations in the mid-IR spectra were used to classify the major pigmenting agent of the Kadaň green earth as ferruginous smectite with separately diffracting saponite-like clusters. The smectite contains ∼15% Fe, mainly in the trivalent form, a detectable fraction of Fe in tetrahedral sites, and it is accompanied by a significant amount of Ti-bearing relict minerals due to its volcanogenic origin. On the contrary, in green micas (glauconite and celadonite) the Ti content is much smaller. Diffuse reflectance spectroscopy was found suitable for distinguishing Fe as a constituent of free Fe oxides from Fe in the clay structure. It was also found to be useful for discriminating between green micas and smectites.
Assay-Specific Decision Limits for Two New Automated Parathyroid Hormone and 25-Hydroxyvitamin D Assays
Authors: Souberbielle Jean-Claude , Fayol Véronique , Sault Corinne , Lawson-Body Ethel , Kahan André , Cormier Catherine
Published: November 2004

Background: The recent development of nonradioactive automated assays for serum parathyroid hormone (PTH) and 25-hydroxyvitamin D (25OHD) has made measurement of these two hormones possible in many laboratories. In this study, we compared two new assays for PTH and 25OHD adapted on an automated analyzer, the LIAISON®, with two manual immunoassays used worldwide.

Methods: We studied 228 osteoporotic patients, 927 healthy individuals, 38 patients with primary hyperparathyroidism, and 167 hemodialyzed patients. Serum PTH was measured with the Allegro® and the LIAISON assays, and 25OHD was measured with DiaSorin RIA and the LIAISON assay. Regression analysis was used to calculate decision thresholds for the LIAISON assays that were equivalent to those of the Allegro PTH and DiaSorin 25OHD assays.

Results: The 25OHD concentrations obtained with the LIAISON assay and the RIA in osteoporotic patients were well correlated (r = 0.83; P <0.001). Regression and Bland–Altman analyses suggested that the LIAISON 25OHD assay reads lower than the DiaSorin RIA at low concentrations but higher at high concentrations. However, the cutoff (50 nmol/L) used in our laboratories to define vitamin D insufficiency with the DiaSorin RIA is applicable to the LIAISON 25OHD assay. In 927 healthy individuals, the 3rd–97th percentile intervals were 3–80 ng/L and 13–151 nmol/L for the LIAISON PTH and 25OHD concentrations, respectively. However, 506 individuals (54.6%) were vitamin D-insufficient; we therefore considered only the 421 individuals with a LIAISON 25OHD >50 nmol/L as eligible for the reference population for the LIAISON PTH assay. In this group, the 3rd–97th percentile interval for LIAISON PTH was 3–51 ng/L. Considering upper reference limits of 46 and 51 ng/L for the Allegro and LIAISON assays, respectively, the frequency of above-normal PTH concentrations in patients with primary hyperparathyroidism was similar in both assays. Regression analysis between serum PTH measured by the Allegro and LIAISON assays in 167 hemodialyzed patients and the corresponding Bland–Altman analysis of these data suggest that the LIAISON PTH assay tends to read higher than the Allegro assay at low concentrations but lower at high concentrations (>300 ng/L).

Conclusions: Because clinical decision limits for both PTH and 25OHD should be assay specific, we propose equivalences between these assays and two manual assays used worldwide. These assay-specific decision limits should help potential users of the LIAISON PTH and 25OHD assays.
Plasma Concentrations of Cystatin C in Patients with Coronary Heart Disease and Risk for Secondary Cardiovascular Events: More than Simply a Marker of Glomerular Filtration Rate
Authors: Koenig Wolfgang , Twardella Dorothee , Brenner Hermann , Rothenbacher Dietrich
Published: November 2004

Background: Renal impairment (RI) is associated with worse prognosis. Recently, cystatin C has been shown to represent a potentially superior marker of the glomerular filtration rate compared with creatinine clearance (CrCl). We evaluated the impact of cystatin C and other markers of RI on prognosis in a large cohort of patients with coronary heart disease (CHD).

Methods: Cystatin C, creatinine (Cr), and CrCl were determined at baseline in a cohort of 1033 patients (30–70 years) with CHD. Patients were followed for a mean of 33.5 months, and a combined endpoint [fatal and nonfatal cardiovascular disease (CVD) events] was used as the outcome variable. Cystatin C was measured by immunonephelometry, and CrCl was calculated.

Results: During follow-up, 71 patients (6.9%) experienced a secondary CVD event. Neither Cr (P = 0.63) nor CrCl (P = 0.10) were associated with incidence of CVD events, whereas cystatin C was clearly associated with risk of secondary CVD events (P <0.0001). In multivariate analyses, patients in the top quintile of the cystatin C distribution at baseline had a statistically significantly increased risk of secondary CVD events even after adjustment for classic risk factors, severity of coronary disease, history of diabetes mellitus, treatment with angiotensin-converting enzyme inhibitors, and C-reactive protein (hazard ratio, 2.27; 95% confidence interval, 1.05–4.91) compared with patients in the bottom quintile.

Conclusions: These data support the possibly important prognostic value of cystatin C among patients with known CHD and suggest that it may be a useful clinical marker providing complementary information to established risk determinants.
Spatial variability, distribution and uncertainty assessment of soil phosphorus in a south Florida wetland
Authors: Grunwald S. , Reddy K. R. , Newman S. , DeBusk W. F.
Published: November 2004

Phosphorus enrichment has been of major concern in the Greater Everglades (GE) ecosystem since the early 1980s. Our objectives were to estimate spatio–temporal patterns of soil total phosphorus (TP) in Water Conservation Area 2A (WCA‐2A) in the GE ecosystem and to compare two different geostatistical methods: ordinary kriging (OK) and conditional sequential Gaussian simulation (CSGS), addressing spatial variability, continuity and uncertainty of TP estimations.

Overall, TP estimated with OK and CSGS were higher in 1998 than in 1990. Both methods generated spatial patterns of TP in 1998 which showed a spatial expansion of the phosphorus enrichment identified in the 1990 dataset. Cross‐validation using OK produced a mean prediction error of −10.71 (1990) and −6.07 (1998). CSGS modeled the spatial uncertainty of TP estimations explicitly with 50 generated realizations. Uncertainty was modeled using the E‐type mean of TP, which ranged from 216 to 2100 mg kg−1 in 1990 and 325.2 to 3660 mg kg−1 in 1998. Standard deviations ranged from 0 to 550 mg kg−1 maximum.

To evaluate TP exceeding a threshold of 450 TP mg kg−1, which represents natural historic wetland conditions, we produced probability maps. Results suggested a distinctly higher retention of TP using CSGS when compared to the OK generated probability maps. Spatial probability patterns are valuable to guide the restoration process of this wetland.

Jackknifing was used to estimate the bias of the descriptive statistics and semivariance. The total number of samples was robust enough to produce stable variograms; however, jackknifing suggested that more samples at closer distances from each other should be collected to reduce the uncertainty of the semivariance and to address short‐range spatial variability. Copyright © 2004 John Wiley & Sons, Ltd.
Is the Mandelbrot set computable?
Authors: Hertling Peter
Published: November 2004

This work is concerned with the question whether the Mandelbrot set is computable. The computability notions that we consider are studied in computable analysis and will be introduced and discussed. We show that the exterior of the Mandelbrot set, the boundary of the Mandelbrot set, and the hyperbolic components satisfy certain natural computability conditions. We conclude that the two‐sided distance function of the Mandelbrot set is computable if the famous hyperbolicity conjecture is true. We also formulate the question whether the distance function of the Mandelbrot set is computable in terms of the escape time. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Effective Borel measurability and reducibility of functions
Authors: Brattka Vasco
Published: November 2004

The investigation of computational properties of discontinuous functions is an important concern in computable analysis. One method to deal with this subject is to consider effective variants of Borel measurable functions. We introduce such a notion of Borel computability for single‐valued as well as for multi‐valued functions by a direct effectivization of the classical definition. On Baire space the finite levels of the resulting hierarchy of functions can be characterized using a notion of reducibility for functions and corresponding complete functions. We use this classification and an effective version of a Selection Theorem of Bhattacharya‐Srivastava in order to prove a generalization of the Representation Theorem of Kreitz‐Weihrauch for Borel measurable functions on computable metric spaces: such functions are Borel measurable on a certain finite level, if and only if they admit a realizer on Baire space of the same quality. This Representation Theorem enables us to introduce a realizer reducibility for functions on metric spaces and we can extend the completeness result to this reducibility. Besides being very useful by itself, this reducibility leads to a new and effective proof of the Banach‐Hausdorff‐Lebesgue Theorem which connects Borel measurable functions with the Baire functions. Hence, for certain metric spaces the class of Borel computable functions on a certain level is exactly the class of functions which can be expressed as a limit of a pointwise convergent and computable sequence of functions of the next lower level. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Investigation of porous GaAs layers formed on n+‐type GaAs by electrochemical anodization in HF solution
Authors: Beji L. , Sfaxi L. , BenOuada H. , Maaref H.
Published: November 2004

The electrochemical etching of n+‐type GaAs in a hydrofluoric acid (HF) solution results in the formation of a porous layer. The current–potential characteristic I(V) of the n+‐type GaAs–HF electrolyte interface shows that pore formation started at a breakdown anodic potential of about 2.5 V independent of the HF concentration. In addition, it is also shown that an electropolishing of the semiconductor started over a critical anodic potential value. The morphology and photoluminescence (PL) of the porous samples were investigated. It has been shown that the porous layer surface morphology consists of arbitrarily shaped crystallites, the pores grow deeply in the substrate and, under some electrochemical conditions, etch pits can be formed. The porous layers exhibited an intense and broad PL band, compared to that of the starting GaAs, composed of elementary bands located below and above the band gap of the starting GaAs. The elementary bands located above the band gap were attributed to GaAs nanocrystals. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Electrochemical deposition and characterization of CoFe2O4 thin films
Authors: Sartale S. D. , Lokhande C. D. , Ganesan V.
Published: November 2004

An electrochemical deposition process, which is a combination of electrodeposition of CoFe2 alloy from an ethylene glycol bath followed by its anodization at ambient temperature, is used to deposit CoFe2O4 thin films on different conducting substrates. Various deposition conditions are studied and optimized. The films have spinel CoFe2O4 structure with crystallite size less than 50 nm. The films are adherent and covered the substrates well. The films are annealed in air at 500 °C for 1 h and the observed properties are reported. After annealing the films have smooth and compact surfaces with improved magnetic properties. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Characterization of non‐Cr‐based deoxidizers on Al alloy 7475‐T7651
Authors: Toh S.K. , Hughes A.E. , McCulloch D.G. , duPlessis J. , Stonham A.
Published: November 2004

The effects of three non‐chromate‐based deoxidizers, namely NaBrO3/HNO3, (NH4)4Ce(SO4)4/H2SO4 and Fe(III)/HF/HNO3, on the Al alloy 7475‐T7651 were investigated. Several analytical methods were employed, including SEM, AES, transmission electron microscopy (TEM), electron energy‐loss spectroscopy (EELS) and glow discharge optical emission spectrometry (GDOES), to study the effects on the surface of this alloy after each treatment compared with the as‐received and alkaline‐cleaned alloy surfaces. The untreated alloy was found to have a thick oxide of 200–320 nm, consisting mainly of MgO. Alkaline cleaning results in an etching effect that thins the oxide and also deposits a thin silicate layer on the surface. In the case of the deoxidizers, there is significant removal of the native oxide of the alloy by the NaBrO3/HNO3 deoxidizer. There is also evidence of intermetallic attack on the alloy. The (NH4)4Ce(SO4)4/H2SO4 deoxidizer, which is a low‐etch‐rate deoxidizer, resulted in a slight thinning of the oxide. However, the effect was not significantly greater than with alkaline cleaning alone. The most effective deoxidizer in reducing the oxide thickness of the alloy is Fe(III)/HF/HNO3, in which the etch rate was sufficiently high to remove completely the native oxide. In this case, equilibrium between oxide removal and the formation of new oxides on the alloy surface was achieved. Copyright © 2004 John Wiley & Sons, Ltd.