bluuebunny/crossref_metadata_2025 huggingface dataset:
DATA ENVELOPMENT ANALYSIS WITH IMPRECISE DATA: AN APPLICATION OF TAIWAN MACHINERY FIRMS
Authors: KAO CHIANG , LIU SHIANG-TAI
Published: May 2005

Technology and management are two broad categories of factors that have major influence on the productivity of manufacturing firms. The ratio of the actual productivity of a firm to its maximal productivity is a measure of efficiency. Since the automation technology level and production management achievement of a firm cannot be measured precisely, a fuzzy data envelopment analysis (FDEA) model is applied to calculate the efficiency scores of a sample of machinery firms in Taiwan. Different from the conventional crisp DEA, the efficiency scores calculated from the FDEA model are fuzzy numbers, in that ranges of values at different possibility levels rather than a single crisp value are provided. When the observations are fuzzy in nature, the FDEA methodology avoids the top management from being over-confident with the results as opposed to that of using the conventional DEA methodology by simplifying the fuzzy observations to crisp values.
A comparison of the geochemistry of aquatic sediments and the fine (<63 μm) till fraction in Finland
Authors: Mäkinen J.
Published: May 2005

A comparison is provided of the composition of aquatic sediments in Finland relative to that of the fine fraction (<63 μm) in till. The study is based on till samples collected throughout the country and 158 sediment cores from 122 Finnish lakes. Element concentration data were obtained by aqua regia (till) and nitric acid (sediment) extraction. The material was divided stratigraphically into four classes: till, pre-isolation sediments, immediate post-isolation sediments, and the top of the sediment column. Mean element concentrations were usually lower in the till fines than in the sediments; only Cu, K, Mg and Ni in the top sediments from the lakes approach the mean concentrations in till. The mean P concentration in the pre-isolation sediments was lower than that in till. Spatial comparison showed the highest statistically significant Pearson and Spearman correlations between the till and lake sediment results to be for Al, Cr, Cu, K, Mg and Ni (
r
= 0.34–0.64), although still higher coefficients were recorded for certain ratios between elements (
r
= 0.73 for K/Cr). No statistically significant correlations within the till–sediment system were observed in the case of Mn, P and V concentrations, and correlation for Fe varied depending on the system. A better correlation between till and lake sediments was observed in supra-aquatic than in sub-aquatic areas. The results also indicate that the sediments of large lakes (>10 km
2
) resemble the mean composition of till better than do those of small lakes (<10 km
2
), and that a statistically significant relationship exists between the clay fraction (<2 μm) in sediments and the K concentration in till.
The Fe/Na ratio, a framework for modelling trace element distributions in Jamaican soils
Authors: Garrett Robert G. , Lalor Gerald C.
Published: May 2005

The trace element geochemistry of Jamaican soils (<150 μm) is extremely variable due to their development on diverse parent materials, varying maturity (ages range from recent to >5 Ma) and the variety of soil-forming processes. It is demonstrated that the Fe/Na ratio of the soils forms a useful quantitative framework for studying trace element distributions. The ratio varies 2.5 orders of magnitude from <2 in newly developed inceptisols to >500 in oxisols and
terra rossas
that have been developing for >5 Ma. The form of the trace element distributions with respect to Fe/Na ratio may be interpreted in the context of mineralogy of the parent material, removal of labile trace element fractions during soil development, sequestration in stable secondary forms, and ultimate concentration of stable primary resistate and secondary minerals by
terra rossa
soil formation processes that lead to elevated Fe and Al levels and the depletion of silica and base cations, Ca
2+
, Mg
2+
, Na
+
and K
+
. As examples, the distributions of U and As are modelled as functions of the Fe/Na ratio. Use of robust regression procedures identifies individual soil samples that exhibit divergent patterns of trace element concentration. Some of these can be linked to local bedrock sources, while others are more likely related to exotic volcanic ash-fall material from Central America deposited on proto-Jamaica in the late Miocene.
The design and application of sequential extractions for mercury, Part 1. Optimization of HNO
3
extraction for all non-sulphide forms of Hg
Authors: Hall Gwendy E. M. , Pelchat Pierre , Percival Jeanne B.
Published: May 2005

The final step in a sequential extraction procedure for Hg in geological samples usually involves a strong acid attack such as aqua regia. It is assumed that the Hg component measured in this step represents HgS (cinnabar), the common and highly insoluble form of Hg in nature. This paper describes the optimization of an HNO
3
-based dissolution of all non-sulphide forms of Hg while minimizing the solubilization of HgS. Previous work indicated that 12M (75% v/v) HNO
3
would fulfil that objective but its application in this work to samples containing very fine-grained HgS showed that this concentration was too strong as it partially dissolved HgS. Thus, HgS control samples were used to study the effect of HNO
3
concentration, duration of extraction and sample-to-volume ratio on the chemical breakdown of HgS. The recommended procedure to separate HgS from other forms of Hg is a two-hour extraction of 1 g of sample in 20 ml of 40% HNO
3
with constant agitation followed by a 10-ml rinse with 40% HNO
3
. This then ensures that all the cinnabar, fine- and coarse-grained, reports to the subsequent aqua regia step.
The design and application of sequential extractions for mercury, Part 2. Resorption of mercury onto the sample during leaching
Authors: Hall Gwendy E. M. , Pelchat Pierre
Published: May 2005

This paper examines the stability of Hg in a six-step sequential extraction scheme, focusing in particular on the first leach designed to extract ‘soluble’ Hg in sediment and soil samples. The recovery of Hg as a spike (Hg
2+
, equivalent to 15 ng g
−1
in a sample), alone and mixed with a background granite ‘GG’, was found to be low and dependent on the time of extraction (15–60 min) in the following reagents: Ca(NO
3
)
2
, NaNO
3
, KNO
3
, CaCl
2
and MgCl
2
. While the complexing action of thiourea stabilized Hg in solution (0.1M Ca(NO
3
)
2
), it also acted as an extractant itself and therefore could not be used to minimize resorption of Hg onto the sample during leaching.

The minerals Hg
2
Cl
2
, HgCl
2
, HgO (red and yellow), HgS (synthetic and cinnabar) and Hg (0) were used alone and mixed with GG to evaluate the selectivity of the scheme. The reagents used in sequence are as follows: 0.01M Ca(NO
3
)
2
(categorized as ‘easily soluble’, F1); 0.1M Na
4
P
2
O
7
(labile organic component, F2); 0.25M NH
2
OH.HCl/0.25M HCl (amorphous Fe and Al oxides, F3); 1M NH
2
OH.HCl/25% CH
3
COOH (crystalline Fe and Al, F4); 40% HNO
3
(non-labile organic component and elemental Hg, F5); and aqua regia (residual phase, containing sulphides (HgS), oxides, some silicates, refractory organics etc., F6). Alone, each mineral dissolved fully in the appropriate reagent, for example: HgCl
2
in F1 (soluble), HgO in F3 (with amorphous Fe/Al oxide phase), Hg (0) in F5, and HgS in the final aqua regia digestion. However, when mixed with GG, these minerals (except HgS) also dissolved in subsequent stronger leaches. For example, Hg in the sample HgCl
2
mixed with GG (total Hg concentration of 513 ng g
−1
) dissolved in F1, F2, F4 and F5. Thus, resorption in the initial leaches of a sequential extraction can confound the results for Hg and lead to incorrect results and interpretation of leaches purported to define the bioavailable component of Hg in environmental materials. New methods should be designed to minimize this phenomenon, using, for example, a flow-through system to achieve short contact times.
Continuous leach inductively coupled plasma mass spectrometry: applications for exploration and environmental geochemistry
Authors: MacFarlane W.R. , Kyser T.K. , Chipley D. , Beauchemin D. , Oates C.
Published: May 2005

Continuous leach inductively coupled plasma mass spectrometry (CL-ICP-MS) is a new analytical technique developed to address some of the shortcomings of bulk leach techniques while overcoming the uncertainties associated with interpreting selective extraction data. It provides information on the specific geochemical sites and mineral phases from which elements are being released using real-time data generated by continually analysing progressively reactive solutions from water to 30% nitric acid as they are pumped through a sample directly into a high resolution ICP mass spectrometer. Mineral breakdown reactions can be monitored from the major elements released, thereby eliminating uncertainties related to host phase/trace element associations. By comparing major and minor element release patterns, trace elements can be reliably assigned to host phases. Results from single mineral phases, mixtures of mineral phases, and natural ore samples indicate that the release of elements from specific minerals is not obscured in more complex samples and that reprecipitation and back reactions are not a concern with this method. Scanning electron micrograph (SEM) examination of the reaction products has been used to verify which phases react and to support the CL-ICP-MS data interpretation. Results for natural soil samples indicate that ‘false’ mobile element anomalies can be identified using CL-ICP-MS and underscore the importance of understanding where trace elements reside in samples used for environmental studies or mineral exploration.
Relationship between groundwater chemistry and soil geochemical anomalies at the Spence copper porphyry deposit, Chile
Authors: Cameron Eion M. , Leybourne Matthew I.
Published: May 2005

Spence is a supergene-enriched copper porphyry deposit located between Antofagasta and Calama in the Atacama Desert of northern Chile. Porphyry intrusion and hypogene mineralization took place during the Palaeocene. Following supergene enrichment that produced an atacamite–brochantite assemblage in the oxide zone, the deposit was covered by 50 to 100 m of piedmont gravels of Miocene age. RioChilex discovered the deposit in 1996 by reconnaissance drilling. This paper describes elemental and isotopic data for groundwaters collected within and peripheral to the deposit and relates these compositions to geochemical anomalies in gravel soils over the deposit. There are two distinct types of groundwater with distinctive isotopic and elemental composition: saline water (average Cl= 11 600 mg/l) extending downflow from the axis of the deposit; and non-saline water (average Cl=1300 mg/l) upflow from the axis. Oxygen and hydrogen isotope ratios imply that the former is a deep formation water and the other is meteoric water derived from precipitation in mountains to the east. The data suggest that the saline formation water flows upward from a permeable fault zone coincident with the long axis of the deposit. This fault may have originally guided the intrusion of the porphyries and the copper-bearing hydrothermal fluids. The saline water has much greater contents of As and Se (up to 129 ppb and 800 ppb, respectively) than the meteoric water (both less than detection limits of 10 and 50 ppb, respectively), but both types have high amounts of Cu within the deposit area. Dispersion of Cu away from the deposit is restricted by adsorption of Cu
2+
on negatively charged hydroxide colloids, whereas As and Se freely disperse dissolved as anions. Reactivation of the axial fault created a permeable fracture zone in the gravels above the deposit. During earthquake activity there was pumping of saline formation water to the surface up this fracture zone, which created soil anomalies. The anomalies are characterized by NaCl, As, Se and Cu. One kilometre to the east of the deposit there is another fracture zone in the gravels, overlying unmineralized basement. Soils above this zone have anomalies for NaCl, As and Se, indicative of flooding by formation water, but lacking Cu.
Correlation of carbon with acid-soluble elements in Finnish lake sediments: two opposite composition trends
Authors: Mäkinen J. , Pajunen H.
Published: May 2005

Rank order correlation coefficients (
r
C,X
) were determined between C and the nitric acid-soluble elements Al, Ba, Ca, Co, Cr, Cu, Fe, K, Mg, Mn, P, S, Sr, Ti, V, Zn and N in lake sediments. Nitrogen and S concentrations increased together with C from the point of isolation towards the top of the sediment, whereas Ca, Cr, Cu, K, Mg, Na, Ni and Ti concentrations decreased. In the case of Al, Ba, Co, Fe, Mn, V and Zn, two divergent patterns were seen, their concentrations either decreasing or increasing towards the top of the sediment. Of the
r
C,P
values, 91% were positive and 9% negative. The sediment cores were classified into three groups on the basis of the correlations between C and Co, Fe, Mn and Zn: (1)
r
C,Co,
r
C,Fe,
r
C,Mn
and
r
C,Zn
statistically significant and negative; (2)
r
C,Co
,
r
C,Fe
,
r
C,Mn
and
r
C,Zn
not statistically significant; and (3)
r
C,Co
,
r
C
,
Fe
,
r
C,Mn
and
r
C,Zn
statistically significant and positive. In the light of the geochemical properties of the sediments, it was concluded that those in group 1 had been deposited under reducing and/or acidic conditions in small, shallow lakes containing high concentrations of C and those in group 3 under oxidative and/or alkaline conditions in large, deep lakes, while those in group 2 represent intermediate forms. It was approximated that C ≤ 9% in sediment provides precipitation of Fe–Mn oxides, but it is impeded by greater C concentrations. Also, sedimentation of terrigenous till material was found to be more effective in small than in large lakes.
PRINCIPLES OF LYSOSOMAL MEMBRANE DIGESTION: Stimulation of Sphingolipid Degradation by Sphingolipid Activator Proteins and Anionic Lysosomal Lipids
Authors: Kolter Thomas , Sandhoff Konrad
Published: May 2005

Sphingolipids and glycosphingolipids are membrane components of eukaryotic cell surfaces. Their constitutive degradation takes place on the surface of intra-endosomal and intra-lysosomal membrane structures. During endocytosis, these intra-lysosomal membranes are formed and prepared for digestion by a lipid-sorting process during which their cholesterol content decreases and the concentration of the negatively charged bis(monoacylglycero)phosphate (BMP)—erroneously also called lysobisphosphatidic acid (LBPA)—increases. Glycosphingolipid degradation requires the presence of water-soluble acid exohydrolases, sphingolipid activator proteins, and anionic phospholipids like BMP. The lysosomal degradation of sphingolipids with short hydrophilic head groups requires the presence of sphingolipid activator proteins (SAPs). These are the saposins (Saps) and the GM2 activator protein. Sphingolipid activator proteins are membrane-perturbing and lipid-binding proteins with different specificities for the bound lipid and the activated enzyme-catalyzed reaction. Their inherited deficiency leads to sphingolipid- and membrane-storage diseases. Sphingolipid activator proteins not only facilitate glycolipid digestion but also act as glycolipid transfer proteins facilitating the association of lipid antigens with immunoreceptors of the CD1 family.
ADVANCES IN CHEMICAL GENETICS
Authors: Smukste Inese , Stockwell Brent R.
Published: May 2005

▪ Abstract  Chemical genetics is an emerging approach for studying biological systems using chemical tools. This strategy aims to reveal the macromolecules responsible for regulating biological systems; thus, the approach shares much in common with genetics. In both strategies, one must (a) develop an assay that reports on a biological process of interest, (b) perturb this process systematically (with mutations or small molecules), and (c) determine the target of each perturbation to reveal macromolecules (i.e., proteins and genes) regulating the process of interest. In this review, we discuss advances and challenges in this field that have emerged over the past four years. Several technologies have converged, raising the hope that it may be possible to systematically apply chemical probes to biological processes.
A possible role for membrane depolarization in epithelial wound healing
Authors: Chifflet Silvia , Hernández Julio A. , Grasso Silvina
Published: May 2005

Linear narrow wounds produced on cultured bovine corneal endothelial monolayers heal by actin cable formation at the wound border and lamellar crawling of cells into the injured area. We report the novel finding that membrane potential depolarization occurs at the leading edge of wounds and gradually extends inward toward the neighboring cells. We have determined that the replacement of extracellular Na+ by choline and the incorporation of phenamil, an inhibitor of the epithelial Na+ channel (ENaC), provoke a decrease in the actin cable and depolarization areas and in the lamellar activity of the wound edges. To the contrary, extracellular Li+ can successfully replace Na+ in the determination of the depolarization and cytoskeletal responses. This finding supports the idea that membrane depolarization, not the increase in intracellular Na+ concentration, is responsible for the formation of the actin cable, a result that is in agreement with previous evidence showing that nonspecific depolarization of the plasma membrane potential (PMP) of epithelial cells may promote characteristic cytoskeletal rearrangements per se (Chifflet S, Hernández JA, Grasso S, and Cirillo A. Exp Cell Res 282: 1–13, 2003). We suggest that spontaneous depolarization of the PMP of the cells at the wound borders determined by a rise in the ENaC activity of these cells constitutes an additional factor in the intermediate cellular processes leading to wound healing in some epithelia.
Inversion of both gating polarity and CO2 sensitivity of voltage gating with D3N mutation of Cx50
Authors: Peracchia Camillo , Peracchia Lillian L.
Published: May 2005

The effect of CO2-induced acidification on transjunctional voltage ( V j) gating was studied by dual voltage-clamp in oocytes expressing mouse connexin 50 (Cx50) or a Cx50 mutant (Cx50-D3N), in which the third residue, aspartate (D), was mutated to asparagine (N). This mutation inverted the gating polarity of Cx50 from positive to negative. CO2 application greatly decreased the V j sensitivity of Cx50 channels, and increased that of Cx50-D3N channels. CO2 also affected the kinetics of V j dependent inactivation of junctional current ( I j), decreasing the gating speed of Cx50 channels and increasing that of Cx50-D3N channels. In addition, the D3N mutation increased the CO2 sensitivity of chemical gating such that even CO2 concentrations as low as 2.5% significantly lowered junctional conductance ( G j). With Cx50 channels G j dropped by 78% with a drop in intracellular pH (pHi) to 6.83, whereas with Cx50-D3N channels G j dropped by 95% with a drop in pHi to just 7.19. We have previously hypothesized that the way in which V j gating reacts to CO2 might be related to connexin’s gating polarity. This hypothesis is confirmed here by evidence that the D3N mutation inverts the gating polarity as well as the effect of CO2 on V j gating sensitivity and speed.
Differential regulation of Ca2+-activated K+ channels by β-adrenoceptors in guinea pig urinary bladder smooth muscle
Authors: Petkov Georgi V. , Nelson Mark T.
Published: May 2005

Stimulation of β-adrenoceptors contributes to the relaxation of urinary bladder smooth muscle (UBSM) through activation of large-conductance Ca2+-activated K+ (BK) channels. We examined the mechanisms by which β-adrenoceptor stimulation leads to an elevation of the activity of BK channels in UBSM. Depolarization from −70 to +10 mV evokes an inward L-type dihydropyridine-sensitive voltage-dependent Ca2+ channel (VDCC) current, followed by outward steady-state and transient BK current. In the presence of ryanodine, which blocks the transient BK currents, isoproterenol, a nonselective β-adrenoceptor agonist, increased the VDCC current by ∼25% and the steady-state BK current by ∼30%. In the presence of the BK channel inhibitor iberiotoxin, isoproterenol did not cause activation of the remaining steady-state K+ current component. Decreasing Ca2+ influx through VDCC by nifedipine or depolarization to +80 mV suppressed the isoproterenol-induced activation of the steady-state BK current. Unlike forskolin, isoproterenol did not change significantly the open probability of single BK channels in the absence of Ca2+ sparks and with VDCC inhibited by nifedipine. Isoproterenol elevated Ca2+ spark (local intracellular Ca2+ release through ryanodine receptors of the sarcoplasmic reticulum) frequency and associated transient BK currents by ∼1.4-fold. The data support the concept that in UBSM β-adrenoceptor stimulation activates BK channels by elevating Ca2+ influx through VDCC and by increasing Ca2+ sparks, but not through a Ca2+-independent mechanism. This study reveals key regulatory molecular and cellular mechanisms of β-adrenergic regulation of BK channels in UBSM that could provide new targets for drugs in the treatment of bladder dysfunction.
Postulated role of interdomain interactions within the type 1 ryanodine receptor in the low gain of Ca2+-induced Ca2+ release activity of mammalian skeletal muscle sarcoplasmic reticulum
Authors: Murayama Takashi , Oba Toshiharu , Kobayashi Shigeki , Ikemoto Noriaki , Ogawa Yasuo
Published: May 2005

Ryanodine receptor (RyR) type 1 (RyR1) exhibits a markedly lower gain of Ca2+-induced Ca2+ release (CICR) activity than RyR type 3 (RyR3) in the sarcoplasmic reticulum (SR) of mammalian skeletal muscle (selective stabilization of the RyR1 channel), and this reduction in the gain is largely eliminated using 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonic acid (CHAPS). We have investigated whether the hypothesized interdomain interactions within RyR1 are involved in the selective stabilization of the channel using [3H]ryanodine binding, single-channel recordings, and Ca2+ release from the SR vesicles. Like CHAPS, domain peptide 4 (DP4, a synthetic peptide corresponding to the Leu2442-Pro2477 region of RyR1), which seems to destabilize the interdomain interactions, markedly stimulated RyR1 but not RyR3. Their activating effects were saturable and nonadditive. Dantrolene, a potent inhibitor of RyR1 used to treat malignant hyperthermia, reversed the effects of DP4 or CHAPS in an identical manner. These findings indicate that RyR1 is activated by DP4 and CHAPS through a common mechanism that is probably mediated by the interdomain interactions. DP4 greatly increased [3H]ryanodine binding to RyR1 with only minor alterations in the sensitivity to endogenous CICR modulators (Ca2+, Mg2+, and adenine nucleotide). However, DP4 sensitized RyR1 four- to six-fold to caffeine in the caffeine-induced Ca2+ release. Thus the gain of CICR activity critically determines the magnitude and threshold of Ca2+ release by drugs such as caffeine. These findings suggest that the low CICR gain of RyR1 is important in normal Ca2+ handling in skeletal muscle and that perturbation of this state may result in muscle diseases such as malignant hyperthermia.
PKC-δ-dependent pathways contribute to PDGF-stimulated ERK1/2 activation in vascular smooth muscle
Authors: Ginnan Roman , Singer Harold A.
Published: May 2005

Platelet-derived growth factor (PDGF) is an important regulator of vascular smooth muscle (VSM) cell growth and migration and has been identified as a key mediator of neointima formation resulting from vascular injury. PDGF exerts its effects, in part, through activation of ERK1/2. Previously, we reported that PKC-δ, specifically compared with PKC-α, mediated phorbol ester- and ATP-dependent activation of ERK1/2 in VSM cells. The purpose of this study was to determine whether PKC-δ was involved in PDGF-dependent activation of ERK1/2 in VSM cells. The addition of PDGF resulted in the activation, and Src family kinase-dependent tyrosine phosphorylation, of PKC-δ. Treatment with rottlerin (0.1–10 μM), a selective PKC-δ inhibitor, or adenoviral overexpression of kinase-negative PKC-δ significantly attenuated PDGF-induced activation of ERK1/2. The effects of the PKC-δ inhibitors decreased with increasing concentrations of activator PDGF. Interestingly, treatment with Gö6976 (0.1–3 μM), a selective inhibitor of cPKCs, or adenoviral overexpression of kinase-negative PKC-α also inhibited PDGF-stimulated ERK1/2. Furthermore, inhibition of cPKC activity with Gö6976 or overexpression of kinase-negative PKC-α attenuated PKC-δ activation and tyrosine phosphorylation in response to PDGF. These studies indicate involvement of both PKC-δ and PKC-α isozymes in PDGF-stimulated signaling in VSM and suggest an unexpected role for PKC-α in the regulation of PKC-δ activity.
Using factorization in analyzing D‐BMAP/G/1 queues
Authors: Lee Ho Woo , Lee Se Won , Jeon Jongwoo
Published: May 2005

We demonstrate how one can use the factorization
property to derive the queue‐length distributions of the
discrete‐time BMAP/G/1 queues with complex operational behavior
during the idle period. The procedure demonstrated in this paper
can be applied to the analysis of many other discrete‐time
BMAP/G/1 queues with more behavioral complexities.
A generalization of Straube′s theorem: existence of absolutely continuous invariant measures for random maps
Authors: Shafiqul Islam Md. , Góra Pawel , Boyarsky Abraham
Published: May 2005

A random map is a discrete‐time dynamical system in which one of a
number of transformations is randomly selected and applied at each
iteration of the process. In this paper, we study random maps. The
main result provides a necessary and sufficient condition for the
existence of absolutely continuous invariant measure for a random
map with constant probabilities and position‐dependent probabilities.
On some stochastic parabolic differential equations in a Hilbert space
Authors: El-Nadi Khairia El-Said
Published: May 2005

We consider some stochastic difference partial differential equations of the form
du(x, t, c) = L(x, t, D)u(x, t, c)dt + M(x, t, D)u(x, t − a, c)dw(t), where
L(x, t, D) is a linear uniformly elliptic partial differential operator of the second order,
M(x, t, D) is a linear partial differential operator of the first order, and w(t) is a Weiner process. The existence and uniqueness
of the solution of suitable mixed problems are studied for the
considered equation. Some properties are also studied. A more
general stochastic problem is considered in a Hilbert space and
the results concerning stochastic partial differential equations
are obtained as applications.
Multiobjective duality withρ − (η, θ)‐invexity
Authors: Nahak C. , Nanda S.
Published: May 2005

Under ρ − (η, θ)‐invexity assumptions on the functions
involved, weak, strong, and converse duality theorems are proved to relate
properly efficient solutions of the primal and dual problems for a
multiobjective programming problem.
Exact and approximate solutions of delay differential equations with nonlocal history conditions
Authors: Agarwal S. , Bahuguna D.
Published: May 2005

We study the exact and approximate solutions of a delay
differential equation with various types of nonlocal history
conditions. We establish the existence and uniqueness of mild,
strong, and classical solutions for a class of such problems using
the method of semidiscretization in time. We also establish a
result concerning the global existence of solutions. Finally, we
consider some examples and discuss their exact and approximate
solutions.
Real almost zeros of random polynomials with complex coefficients
Authors: Farahmand K. , Grigorash A. , Flood P.
Published: May 2005

We present a simple formula for the expected number
of times that a complex‐valued Gaussian stochastic process has a
zero imaginary part and the absolute value of its real part is
bounded by a constant value
M. We show that only some mild
conditions on the stochastic process are needed for our formula to
remain valid. We further apply this formula to a random algebraic
polynomial with complex coefficients. We show how the above
expected value in the case of random algebraic polynomials varies
for different behaviour of
M.
A note on the minimal essential set of coincident points for set‐valued mappings
Authors: Qun Luo
Published: May 2005

Motivated by the ideas of Kinoshita, we introduce the concept of
minimal essential set of the coincident points for set‐valued
mappings, and we prove that there exists at least one minimal
essential set and one essential component of the coincident points
for set‐valued mappings (satisfying some conditions).
On a multidimensional oil exploration problem
Authors: Benkherouf Lakdere , Pitts Susan
Published: May 2005

This paper is concerned with optimal strategies for drilling in an
oil exploration model. An exploration area contains
n1 large and
n2 small oilfields, where
n1 and
n2 are unknown, and
represented by a two‐dimensional prior distribution
π. A single exploration well discovers at most
one oilfield, and the discovery process is governed by some
probabilistic law. Drilling a single well costs
c, and the values of a large and small oilfield are
v1 and
v2 respectively,
v1 > v2 > c > 0. At each time
t = 1, 2, …, the operator is faced with the option of stopping drilling and
retiring with no reward, or continuing drilling. In the event of
drilling, the operator has to choose the number
k,
0 ≤ k ≤ m
(m fixed), of wells to be drilled. Rewards are additive
and discounted geometrically. Based on the entire history of the
process and potentially on future prospects, the operator seeks
the optimal strategy for drilling that maximizes the total
expected return over the infinite horizon. We show that when
π≻π′ in monotone likelihood ratio,
then the optimal expected return under prior
π is greater than or equal to the optimal expected return under
π′. Finally, special cases where explicit
calculations can be done are presented.
Hyperleptinemia
Authors: Unger Roger H.
Published: May 2005

In this review, we attempt to deduce teleologically the physiological mission of leptin. Because overnutrition and diet-induced obesity are the only known causes of hyperleptinemia, we contrast the differences in overnutrition in normally leptinized rodents, in which the added lipids are confined to adipocytes, with those of unleptinized rodents, in which the added lipids are distributed in liver, pancreatic islets, and heart and skeletal muscle, causing organ dysfunction and cell death with a disease cluster resembling metabolic syndrome. We focus here on lipid-induced cardiac dysfunction and the remarkable ability of hyperleptinemia to prevent it. We conclude that the hyperleptinemia of overnutrition prevents the ectopic lipid deposition by: (1) acting on hypothalamic appetite centers to limit the caloric surplus to fit the available adipocyte storage capacity and, (2) upregulating of fatty acid oxidation and downregulating lipogenesis in peripheral tissues to minimize ectopic lipid deposition. The causes of failure of this system and its clinical consequences are discussed.
Blood Pressure Control, Drug Therapy, and Kidney Disease
Authors: Contreras Gabriel , Greene Tom , Agodoa Lawrence Y. , Cheek DeAnna , Junco George , Dowie Donna , Lash James , Lipkowitz Michael , Miller Edgar R. , Ojo Akinlou , Sika Mohammed , Wilkening Beth , Toto Robert D.
Published: May 2005

The African American Study of Kidney Disease and Hypertension examined the effect on renal function decline of 2 blood pressure (BP) goals (low mean arterial pressure [MAP] ≤92 versus usual MAP 102 to 107 mm Hg) and 3 antihypertensives (ramipril versus amlodipine versus metoprolol). We previously reported that in all drug groups combined the BP intervention had similar effects on the primary outcome of glomerular filtration rate (GFR) slope or the main secondary clinical composite outcome of end-stage renal disease (ESRD), death, or GFR decline by 50% or 25 mL/min per 1.73 m
2
. This report examines the effect of the BP intervention separately in the 3 drug groups. The BP effect was similar among the drug groups for either GFR slope or the main clinical composite. However, the BP effect differed significantly among the drug groups for the composite of ESRD or death (
P
=0.035) and ESRD alone (
P
=0.021). Higher event rates for amlodipine patients assigned to the usual BP goal (0.087 per patient-year for ESRD or death and 0.064 per patient-year for ESRD) were seen compared with the remaining groups of the factorial design (range, 0.041 to 0.050 for ESRD or death; and range, 0.027 to 0.036 for ESRD). The low BP goal was associated with reduced risk of ESRD or death (risk reduction 51%; 95% confidence interval, 13% to 73%) and ESRD (54%; 8% to 77%) for amlodipine patients, but not for patients assigned to the other drug groups. These secondary analyses suggest a benefit of the low BP goal among patients assigned to amlodipine, but they must be interpreted cautiously.
Long-Term Impact of Systolic Blood Pressure and Glycemia on the Development of Microalbuminuria in Essential Hypertension
Authors: Pascual Jose Maria , Rodilla Enrique , Gonzalez Carmen , Pérez-Hoyos Santiago , Redon Josep
Published: May 2005

The objective was to assess the temporal impact of factors related to the development of microalbuminuria during the follow-up of young adult normoalbuminurics with high-normal blood pressure or at stage 1 of essential hypertension. Prospective follow-up was conducted on 245 normoalbuminuric hypertensive subjects (mean age 40.9 years; 134 men; blood pressure 139.7/88.6 mm Hg; body mass index 28.5 kg/m
2
) never treated previously with antihypertensive drugs, with yearly urinary albumin excretion measurements, until the development of microalbuminuria. After enrollment, patients were placed on usual care including nonpharmacological treatment or with an antihypertensive drug regime to achieve a blood pressure of <135/85 mm Hg. Thirty subjects (12.2%) developed microalbuminuria after a mean follow-up of 29.9 months (range 12 to 144 months), 2.5 per 100 patients per year. Baseline urinary albumin excretion (hazard ratio, 1.07;
P
=0.006) and systolic blood pressure during the follow-up (hazard ratio, 1.03;
P
=0.008) were independent factors related to the follow-up urinary albumin excretion in a Cox proportional hazard model. A significant increase in the risk of developing microalbuminuria for urinary albumin excretion at baseline >15 mg per 24-hour systolic blood pressure >139 mm Hg and a positive trend in fasting glucose were observed in the univariate analyses. However, in the multivariate analysis, only the baseline urinary albumin excretion and the trend of fasting glucose were independently related to the risk of developing microalbuminuria. In mild hypertensives, the development of microalbuminuria was linked to insufficient blood pressure control and to a progressive increment of glucose values.
Antiangiogenesis Mediates Cisplatin-Induced Peripheral Neuropathy
Authors: Kirchmair Rudolf , Walter Dirk H. , Ii Masaaki , Rittig Kilian , Tietz Anne B. , Murayama Toshinori , Emanueli Costanza , Silver Marcy , Wecker Andrea , Amant Carole , Schratzberger Peter , Yoon Young-Sup , Weber Alberto , Panagiotou Eleftheria , Rosen Kenneth M. , Bahlmann Ferdinand H. , Adelman Lester S. , Weinberg David H. , Ropper Allan H. , Isner Jeffrey M. , Losordo Douglas W.
Published: May 2005

Background—

Toxic neuropathies induced by cisplatin and other chemotherapeutic agents are important clinical problems because of their high incidence, their lack of effective treatment, and the fact that neuropathy represents a dose-limiting factor for these therapies. The pathogenic basis for toxic neuropathies induced by chemotherapeutic agents has not been completely elucidated.

Methods and Results—

We investigated the hypothesis that experimental toxic neuropathy results from an antiangiogenic effect of these drugs, resulting in destruction of the vasa nervorum, and accordingly that the neuropathy could be prevented or reversed by locally administered VEGF gene transfer without augmenting tumor growth. In an animal model of cisplatin-induced neuropathy, nerve blood flow was markedly attenuated, and there was a profound reduction in the number of vasa nervorum associated with marked endothelial cell apoptosis, resulting in a severe peripheral neuropathy with focal axonal degeneration characteristic of ischemic neuropathy. After intramuscular gene transfer of naked plasmid DNA encoding VEGF-1 in animals with an established neuropathy, vascularity and blood flow returned to levels similar to those of control rats, peripheral nerve function was restored, and histological nerve architecture was normalized. Gene therapy administered in parallel with cisplatin chemotherapy completely attenuated endothelial cell apoptosis and inhibited destruction of nerve vasculature, deterioration of nerve function, and axonal degeneration. In a rat tumor model, VEGF gene transfer administered locally did not alter tumor growth or vascularity.

Conclusions—

These findings implicate microvascular damage as the basis for toxic neuropathy induced by cisplatin and suggest that local angiogenic gene therapy may constitute a novel prevention or treatment for this disorder without augmenting tumor growth or vascularization.
Quantitative Assessment of Regional Myocardial Function in Mice by Tissue Doppler Imaging
Authors: Sebag Igal A. , Handschumacher Mark D. , Ichinose Fumito , Morgan John G. , Hataishi Ryuji , Rodrigues Ana Clara T. , Guerrero J. Luis , Steudel Wolfgang , Raher Michael J. , Halpern Elkan F. , Derumeaux Geneviève , Bloch Kenneth D. , Picard Michael H. , Scherrer-Crosbie Marielle
Published: May 2005

Background—

Tissue Doppler imaging (TDI) is a novel echocardiographic method to quantify regional myocardial function. The objective of this study was to assess whether myocardial velocities and strain rate (SR) could be obtained by TDI in mice and whether these indices accurately quantified alterations in left ventricular (LV) systolic function.

Methods and Results—

TDI was performed in 10 healthy mice to measure endocardial (v
endo
) and epicardial systolic velocities and SR. In further experiments, TDI indices were compared with dP/dt
max
and with sonomicrometer-derived regional velocities, at rest and after administration of dobutamine or esmolol. TDI indices were also studied serially in 8 mice before and 4 and 7 hours after endotoxin challenge. Myocardial velocities and SR were obtained in all mice with low measurement variability. TDI indices increased with administration of dobutamine (v
endo
from 2.2±0.3 to 3.8±0.2 cm/s [
P
<0.01]; SR from 12±2 to 20±2 s
−1
[
P
<0.05]) and decreased with administration of esmolol (v
endo
1.4±0.2 cm/s [
P
<0.05]; SR 6±1 s
−1
[
P
<0.01]). Both indices correlated strongly with dP/dt
max
(
r
2
=0.79 for SR and
r
2
= 0.69 for v
endo
; both
P
<0.0001). SR and shortening fraction were predictors of dP/dt
max
even after adjustment for the confounding effect of the other variables. V
endo
correlated closely with sonomicrometer-measured velocity (
r
2
=0.71,
P
<0.0005). After endotoxin challenge, decreases in both v
endo
and SR were detected before decreases in shortening fraction became manifest.

Conclusions—

Myocardial velocities and SR can be measured noninvasively in mice with the use of TDI. Both indices are sensitive markers for quantifying LV global and regional function in mice.
Ventricular Myocyte Caspases Are Directly Responsible for Endotoxin-Induced Cardiac Dysfunction
Authors: Lancel Steve , Joulin Olivier , Favory Raphael , Goossens Jean Francois , Kluza Jérome , Chopin Claude , Formstecher Pierre , Marchetti Philippe , Neviere Remi
Published: May 2005

Background—

Although most of the deleterious effects of sepsis-induced apoptosis have been attributed to increased lymphocyte cell death, caspase activation may directly alter cell function of different organ systems. We postulated that left ventricular (LV) cardiomyocyte caspase activation is directly involved in sepsis-induced heart contractile dysfunction.

Methods and Results—

LV cardiomyocytes isolated 4 hours after rat treatment with endotoxin injection (10 mg/kg) displayed major reductions in contractile reserve and myofilament response to Ca
2+
. Concomitantly, endotoxin also induced increases in LV cardiomyocyte caspase-3, -8, and -9-like activities, which were associated with sarcomeric structure destruction and cleavage of components of the cardiac myofilament. Interestingly, zVAD.fmk treatment of septic rat prevented LV cardiomyocyte contractile dysfunction, reductions in myofilament response to calcium, troponin T cleavage, and sarcomere destruction. Serum (10%) of endotoxin-treated rats induced contractile dysfunction, caspase-3–like activity increase, and troponin T cleavage of naive LV cardiomyocytes. The effects of septic serum were prevented in LV cardiomyocytes isolated from zVAD.fmk- or zDEVD.cmk-treated rats or LV cardiomyocytes preincubated with zVAD.fmk or zDEVD.cmk.

Conclusions—

The results show an important relationship between endotoxin-induced caspase activation and reduced contractile reserve and sarcomere disarray at the level of single LV cardiomyocytes.
Restoration of β-Adrenergic Receptor Signaling and Contractile Function in Heart Failure by Disruption of the βARK1/Phosphoinositide 3-Kinase Complex
Authors: Perrino Cinzia , Naga Prasad Sathyamangla V. , Schroder Jacob N. , Hata Jonathan A. , Milano Carmelo , Rockman Howard A.
Published: May 2005

Background—

Desensitization and downregulation of myocardial β-adrenergic receptors (βARs) are initiated by the increase in βAR kinase 1 (βARK1) levels. By interacting with βARK1 through the phosphoinositide kinase (PIK) domain, phosphoinositide 3-kinase (PI3K) is targeted to agonist-stimulated βARs, where it regulates endocytosis. We tested the hypothesis that inhibition of receptor-targeted PI3K activity would alter receptor trafficking and ameliorate βAR signaling, ultimately improving contractility of failing cardiomyocytes.

Methods and Results—

To competitively displace PI3K from βARK1, we generated mice with cardiac-specific overexpression of the PIK domain. Seven-day isoproterenol administration in wild-type mice induced desensitization of βARs and their redistribution from the plasma membrane to early and late endosomes. In contrast, transgenic PIK overexpression prevented the redistribution of βARs away from the plasma membrane and preserved their responsiveness to agonist. We further tested whether PIK overexpression could normalize already established βAR abnormalities and ameliorate contractile dysfunction in a large animal model of heart failure induced by rapid ventricular pacing in pigs. Failing porcine hearts showed increased βARK1-associated PI3K activity and marked desensitization and redistribution of βARs to endosomal compartments. Importantly, adenoviral gene transfer of the PIK domain in failing pig myocytes resulted in reduced receptor-localized PI3K activity and restored to nearly normal agonist-stimulated cardiomyocyte contractility.

Conclusions—

These data indicate that the heart failure state is associated with a maladaptive redistribution of βARs away from the plasma membrane that can be counteracted through a strategy that targets the βARK1/PI3K complex.
CITYCLUSTER “From the Renaissance to the Megabyte Networking Age”: A Virtual Reality and High-Speed Networking Project
Authors: Fischnaller Franz , Hill Alex
Published: May 2005

This paper presents the CITYCLUSTER project, a virtual-reality networking matrix, in a high-tech framework with original technological features, navigation, interactivity, graphic, and content style, in which multiple environments, ambiences, and cities, both real and imagined, can be hosted, coexist, and be interrelated within themselves through a common virtual territory. It can be interconnected by high-speed network, enabling remote participants to access, interact, and collaborate in shared environments and work together in a common virtual space over distance in real time. The framework can be expanded and modified in accordance with the digital environment to be incorporated. Meta-Net-Page, a virtual-reality collaborative networking tool, was designed and implemented ad hoc for CITYCLUSTER.

“From the Renaissance to the Megabyte Networking Age” is the first CITY-CLUSTER virtual-reality networked application, which offers visitors a thrilling interactive journey, from the Renaissance to the Super Broadband Networking and Electronic Age. Florence represents the “Renaissance Age”, Chicago the “Gigabits Networking Age.” Each virtual city is inhabited by a group of avatars: David, Venus, and Machiavelli in Florence, and Mega, Giga, and Picasso in Chicago.

The implementation of CITYCLUSTER has given rise to a range of technological challenges, which in turn have revealed innovative aspects and salient features relative to content management, the development of juxtaposed virtual environments, networking interactive techniques, avatar design, architecture, and virtual effects. A series of special features and enhancements have been added to the software Ygdrasil, to satisfy content and quality levels of interactivity. In consequence, the Ygdrasil system was further refined as software tools that aid the rapid and intuitive development of interactive virtual environments for artists and other nontechnical users.

The CITYCLUSTER project is primarily designed to run in the CAVE and on the AGAVE (Access Grid Augmented Virtual Environment). It can run either locally or through remote networking in both SGIs and the Linux platform.
From Spatial Proximity to Semantic Coherence: A Quantitative Approach to the Study of Group Dynamics in Collaborative Virtual Environments
Authors: Chen Chaomei , Börner Katy
Published: May 2005

This article describes a quantitative approach to the study of group dynamics in Collaborative Information Visualization Environments (CIVEs). This approach characterizes group dynamics in terms of two concepts introduced in this article—spatial proximity and semantic coherence. The concepts are crucial to the understanding of profound interrelationships between spatial, semantic, and social navigation. Furthermore, this article describes three visualization techniques—semantic indentation chat sequence displays, activity maps, and clock-face maps—that permit the identification of important features of group interaction that are related to semantic coherence and spatial proximity. The approach is illustrated by applying it to the analysis of an empirical study in which four groups of subjects performed collaborative search tasks through 3D visualizations of knowledge domains. The major contribution of the work is the conceptualization and quantification of group coherence as a generic methodology for the study of a range of collaborative virtual environments such as collaborative learning, distance learning, social networks, collaborative information visualization, and digital libraries. Further research challenges for the study of group behavior in collaborative information-visualization environments are identified.
Wolverine: A Distributed Scene-Graph Library
Authors: Chardavoine François , Ageneau Sylvain , Ozell Benoît
Published: May 2005

In this paper we present Wolverine, a simple scene-graph library that incorporates advanced concepts such as node and object differentiation, seamless serialization for distributed environments, and multimedia elements including dynamic textures and video sources. By examining the specifics of Wolverine, we will compare our approach to other scene-graph APIs and dwell on its use in a videoconferencing shared-reality collaborative application.