bluuebunny/crossref_metadata_2025 huggingface dataset:
Local Etching of Insulator-Coated Carbon Nanotubes towards Passivated Nanoprobes
Authors: Ikuno Takashi , Katayama Mitsuhiro , Lee Kuei-Yi , Kuzuoka Takashi , Lee Jung-Goo , Honda Shin-ichi , Mori Hirotaro , Oura Kenjiro
Published: February 2005

We present a method for local etching of the tip region of insulator-coated carbon nanotubes (CNTs) towards passivated nanoprobes. By reactive ion etching (RIE), a 20-nm-thick SiO2 layer, which was uniformly wrapped around vertically oriented CNTs, was selectively removed from the tip, maintaining the crystallinity of inner CNT. It was found that the length of exposed CNT is controlled via etching time at an etching rate of 16 nm/min. This local etching was achieved by RIE using CF4 as an etchant, and photoresist as a passivation mask.
Non-classical Photon Emission from a Single InAs/InP Quantum Dot in the 1.3-µm Optical-Fiber Band
Authors: Takemoto Kazuya , Sakuma Yoshiki , Hirose Shinichi , Usuki Tatsuya , Yokoyama Naoki , Miyazawa Toshiyuki , Takatsu Motomu , Arakawa Yasuhiko
Published: February 2005

We report the first observation of single-photon emission from a single InAs/InP quantum dot at a telecommunication wavelength. The single quantum dot was developed through a `double-cap' growth method using metalorganic chemical vapor deposition, and its emission covers a wide spectral range of the optical telecommunication band. Using a pulsed excitation source and gated single-photon detection modules, we observed a photon antibunching behavior through a single-mode optical fiber for an isolated exciton emission line at 1277.1 nm in the O-band (1.3 µm).
Static Single-Arm Force Generation With Kinematic Constraints
Authors: Pan Peng , Peshkin Michael A. , Colgate J. Edward , Lynch Kevin M.
Published: February 2005

Smooth, frictionless, kinematic constraints on the motion of a grasped object reduce the motion freedoms at the hand, but add force freedoms, that is, force directions that do not affect the motion of the object. We are studying how subjects make use of these force freedoms in static and dynamic manipulation tasks. In this study, subjects were asked to use their right hand to hold stationary a manipulandum being pulled with constant force along a low-friction linear rail. To accomplish this task, subjects had to apply an equal and opposite force along the rail, but subjects were free to apply a force against the constraint, orthogonal to the pulling force. Although constraint forces increase the magnitude of the total force vector at the hand and have no effect on the task, we found that subjects applied significant constraint forces in a consistent manner dependent on the arm and constraint configurations. We show that these results can be interpreted in terms of an objective function describing how subjects choose a particular hand force from an infinite set of hand forces that accomplish the task. Without assuming any particular form for the objective function, the data show that its level sets are convex and scale invariant (i.e., the level set shapes are independent of the hand-force magnitude). We derive the level sets, or “isocost” contours, of subjects' objective functions directly from the experimental data.
LFP Power Spectra in V1 Cortex: The Graded Effect of Stimulus Contrast
Authors: Henrie J. Andrew , Shapley Robert
Published: February 2005

We recorded local field potentials (LFPs) and single-unit activity simultaneously in the macaque primary visual cortex (V1) and studied their responses to drifting sinusoidal gratings that were chosen to be “optimal” for the single units. Over all stimulus conditions, the LFP spectra have much greater power in the low-frequency band (≤10 Hz) than higher frequencies and can be described as “1/f.” Analysis of the total power limited to the low, gamma (25–90 Hz), or broad (8–240 Hz) frequency bands of the LFP as a function of stimulus contrast indicates that the LFP power gradually increases with stimulus strength across a wide band in a manner roughly comparable to the increase in the simultaneously recorded spike activity. However, the low-frequency band power remains approximately constant across all stimulus contrasts. More specifically the gamma-band LFP power increases differentially more with respect to baseline than either higher or lower bands as stimulus contrast increases. At the highest stimulus contrasts, we report as others have previously, that the power spectrum of the LFP typically contains an obvious peak in the gamma-frequency band. The gamma-band peak emerges from the overall broadband enhancement in LFP power at stimulus contrasts where most single units' responses have begun to saturate. The temporal/spectral structures of the LFP located in the gamma band—which become most evident at the highest contrasts—provide additional constraints on potential mechanisms underlying the stimulus response properties of spiking neurons in V1.
Spontaneous Pallidal Neuronal Activity in Human Dystonia: Comparison With Parkinson’s Disease and Normal Macaque
Authors: Starr Philip A. , Rau Geoff M. , Davis Valerie , Marks William J. , Ostrem Jill L. , Simmons Donn , Lindsey Nadja , Turner Robert S.
Published: February 2005

Dystonia is a movement disorder defined by sustained muscle contractions, causing twisting and repetitive movements and abnormal postures. To understand the abnormalities in pallidal discharge in dystonia, we have analyzed the spontaneous activity of 453 neurons sampled from the internal or external pallidum (GPi or GPe) of 22 patients with dystonia, 140 neurons from 11 patients with Parkinson’s disease (PD), and 157 neurons from two normal non-human primates (NHPs; Macacca mulatta). All recordings were performed without systemic sedation. Mean GPi discharge rate in dystonia was 55.3 ± 1.3 (SE) Hz. This was significantly lower than in the normal NHPs (82.5 ±2.5 Hz) and lower than in PD patients (95.2 ± 2.3 Hz). Mean GPe discharge rate in dystonia (54.0 ± 1.9 Hz) was lower than in the normal NHPs (69.7 ± 3.3 Hz) and was indistinguishable from that in PD patients (56.6 ± 3.5 Hz). Mean GPi discharge rate was inversely correlated with dystonia severity. GPi showed increased oscillatory activity in the 2- to 10-Hz range and increased bursting activity in both dystonia and PD as compared with the normal NHPs. Because the abnormalities in discharge patterns were similar in dystonia compared with PD, we suggest that bursting and oscillatory activity superimposed on a high background discharge rate are associated with parkinsonism, whereas similar bursting and oscillations superimposed on a lower discharge rate are associated with dystonia. Our findings are most consistent with a model of dystonia pathophysiology in which the two striatal cell populations contributing to the direct and indirect intrinsic pathways of the basal ganglia both have increased spontaneous activity.
Real-Time Supervisor System Based on Trinary Logic to Control Experiments With Behaving Animals and Humans
Authors: Kutz D. F. , Marzocchi N. , Fattori P. , Cavalcanti S. , Galletti C.
Published: February 2005

A new method is presented based on trinary logic able to check the state of different control variables and synchronously record the physiological and behavioral data of behaving animals and humans. The basic information structure of the method is a time interval of defined maximum duration, called time slice, during which the supervisor system periodically checks the status of a specific subset of input channels. An experimental condition is a sequence of time slices subsequently executed according to the final status of the previous time slice. The proposed method implements in its data structure the possibility to branch like an if-else cascade and the possibility to repeat parts of it recursively like the while-loop. Therefore its data structure contains the most basic control structures of programming languages. The method was implemented using a real-time version of LabVIEW programming environment to program and control our experimental setup. Using this supervision system, we synchronously record four analog data channels at 500 Hz (including eye movements) and the time stamps of up to six neurons at 100 kHz. The system reacts with a resolution within 1 ms to changes of state of digital input channels. The system is set to react to changes in eye position with a resolution within 4 ms. The time slices, experimental conditions, and data are handled by relational databases. This facilitates the construction of new experimental conditions and data analysis. The proposed implementation allows continuous recording without an inter-trial gap for data storage or task management. The implementation can be used to drive electrophysiological experiments of behaving animals and psychophysical studies with human subjects.
Complement activation: the missing link between ADAMTS-13 deficiency and microvascular thrombosis of thrombotic microangiopathies
Authors: Ruiz-Torres Maria , Casiraghi Federica , Galbusera Miriam , Macconi Daniela , Gastoldi Sara , Todeschini Marta , Porrati Francesca , Belotti Daniela , Pogliani Enrico , Remuzzi Giuseppe , Noris Marina
Published: February 2005

Endothelial injury is the central factor in the events leading to thrombotic microangiopathy (TMA); however, the mechanisms involved are not fully understood. Here we investigate the role of neutrophils (PMNs) and of complement activation in inducing microvascular damage and loss of thromboresistance in TMA associated with ADAMTS-13 deficiency. PMNs isolated during the acute phase of the disease released excessive amounts of reactive-oxygen species (ROS), N-derived oxidants and proteinases and induced damage and thromboresistance loss in human microvascular endothelial cell line (HMEC-1) ex vivo. Endothelial cytotoxicity and thromboresistance loss was also induced by TMA serum. Complement-derived products were responsible for the above effects: in fact, TMA serum caused C3 and Membrane Attack Complex (MAC) deposition on HMEC-1 and its cytotoxic effect was abolished by complement inhibition. TMA serum caused surface expression of P-selectin on HMEC-1 which may promote PMN adhesion and resulted in increased PMN cytotoxicity, indicating that complement may have a role in PMN activation. In addition, TMA serum stimulated control PMNs to release ROS and proteinases, and to cause endothelial cell cytotoxicity. All of the above effects were abrogated by complement inactivation. These data document for the first time that complement-initiated PMN activation and endothelial injury may have a crucial role in microvascular thrombosis of TMA associated with ADAMTS-13 deficiency.
Performance of magnetic resonance angiography in suspected acute pulmonary embolism
Authors: Bellou Abdelouahab , Guillemin Francis , Douek Philippe , Laprévote-Heully Marie-Claude , Wahl Denis , Blum Alain ,   and the GENEPI study group (see appendix)
Published: February 2005

Pulmonary embolism (PE) is a common and potentially fatal disorder. Non-specific findings make the clinical diagnosis of PE difficult. To assess the diagnostic value and inter-observer agreement of magnetic resonance angiography (MRA) in a cohort of patients with suspected PE, we conducted a prospective clinical study. MRA was compared for sensitivity and specificity to a diagnostic strategy including clinical probability, D-dimer testing, spiral CT, ultrasound leg compression and pulmonary angiography. A total of 89 patients with clinically suspected PE were included: the clinical probability of PE was intermediate or high in 78, and low in the remaining 11. All patients underwent mono-or multi-slice spiral CT and MRA with gadolinium injection (both within 24 hours of entry to the study). Anticoagulation was withheld in patients concerned about the strategy. All subjects were followed up for 3 months. MRA was read independently by two experienced teams of radiologists: one local and one from another university centre. Spiral CT was positive in 62 of 63 cases of confirmed PE. No patient with negative CT findings was positive ultrasonographically. Only one patient with a negative CT (and negative ultrasound) had a recurrent thromboembolic event. The first team diagnosed PE with MRA in 47 cases, with a sensitivity of 71% and a specificity of 92%; the second team obtained the diagnosis in 23 cases, with a sensitivity of 31% and a specificity of 85%. Inter-observer agreement between MRA reading was low: Kappa = 0.16 (-0.01 to 0.33); p = 0.07. In conclusion, compared with a non-invasive strategy based on spiral CT, the diagnostic value of MRA is limited by poor inter-observer agreement.
Risk factors associated with symptomatic pulmonary embolism in a large cohort of deep vein thrombosis patients
Authors: Kucher Nils , Tapson Victor , Goldhaber Samuel ,   for the DVT FREE Steering Committee
Published: February 2005

In patients with deep vein thrombosis (DVT), the factors which predispose to concomitant symptomatic pulmonary embolism (PE) have remained uncertain. From a prospective cohort of 5,451 consecutive patients with ultrasound-confirmed DVT, we analyzed 4,211 patients with a known status for presence (n =639) or absence (n = 3572) of symptomatic PE. Age and gender were similar in DVT plus PE (63.7±15.6 years; 49% men) and DVT patients (63.4±17.3 years; 46% men). Body mass index (BMI) was higher in patients with DVT plus PE (median 29.0, range 15.4–67.0 kg/m2) than in patients with DVT (median 26.8, range 9.7–64.4 kg/m2; p < 0.001). Chronic lung disease (17% vs. 12%; p < 0.001), a personal history of PE (11% vs. 6%; p < 0.001), and a family history of DVT or PE (8% vs. 4%; p < 0.001) were more frequent in DVT plus PE patients. Twenty-seven percent of DVT plus PE patients received prophylaxis prior to the thromboembolic event compared with 32% of DVT patients (p=0.002). Proximal DVT (OR 1.84, 95% CI 1.39–2.43), prior PE (OR 1.68, 95% CI 1.20–2.35), obesity (BMI > 30 kg/m2) (OR 1.65, 95% CI 1.33–2.04), chronic lung disease (OR 1.51, 95%CI 1.13–2.01), as well as omission of prophylaxis (OR 1.30, 95%CI 1.04–1.64) emerged as independent predictors of concomitant symptomatic PE.
The alkylating carcinogen N-methyl-N’-nitro-N-nitrosoguanidine activates the plasminogen activator inhibitor-1 gene through sequential phosphorylation of p53 by ATM and ATR kinases
Authors: Jardí Mercè , Saito Shin'ichi , Appella Ettore , Vidal Berta , Parra Maribel , Muñoz-Cánoves Pura
Published: February 2005

The alkylating agent MNNG is an environmental carcinogen that causes DNA lesions leading to cell death. We previously demonstrated that MNNG induced the transcriptional activity of the plasminogen activator inhibitor-1 (PAI-1) gene in a p53-dependent manner. However, the mechanism(s) linking external MNNG stimulation and PAI-1 gene induction remained to be elucidated. Here, we show that ATM and ATR kinases, but not DNA-PK, which participate in DNA damage-activated checkpoints, regulate the phosphorylation of p53 at serine 15 in response to MNNG cell treatment. Using ATM-deficient cells, ATM was shown to be required for early phosphorylation of serine 15 in response to MNNG, whereas catalytically inactive ATR selectively interfered with late phase serine 15 phosphorylation. In contrast, DNA-PK-deficient cells showed no change in the MNNG-induced serine 15 phosphorylation pattern. In agreement with this, sequential activation of ATM and ATR kinases was also required for adequate induction of the endogenous PAI-1 gene by MNNG. Finally, we showed that cells derived from PAI-1-deficient mice were more resistant to MNNG-induced cell death than normal cells, suggesting that p53-dependent PAI-1 expression partially mediated this effect. Since PAI-1 is involved in the control of tumor invasiveness, our finding that MNNG induces PAI-1 gene expression via ATM/ATR-mediated phosphorylation of p53 sheds new insight on the role of these DNA damage-induced cell cycle checkpoint kinases.
Clinical phenotypes and factor VII genotype in congenital factor VII deficiency
Authors: Mariani Guglielmo , Herrmann Falko , Dolce Alberto , Batorova Angelika , Etro Daniela , Peyvandi Flora , Wulff Karin , Schved Jean , Auerswald Günter , Ingerslev Jorgen , Bernardi Francesco ,   for the International Factor VII Deficiency Study Group (see appendix)
Published: February 2005

To investigate the relationship between clinical phenotype, clotting activity (FVIIc) and FVII genotype, a multi-center study of factor VII (FVII) congenital deficiency with centralized genotyping and specific functional assays was carried out. FVII mutations characterized in patients (n=313) were extremely heterogeneous (103 different, 22 novel). Clinical phenotypes ranged from asymptomatic condition, including 15 homozygotes and 14 double heterozygotes, to patients with a severe disease char-acterized by life-threatening and disabling symptoms (CNS, GI bleeding and hemarthrosis) strongly associated with an early age of presentation. Based on type and number of symptoms we classified 90 'severe' (median FVIIc 1.4%, IQR [Interquartile Range] 0.9–3.8), 83 'moderate' (FVIIc 3%, IQR 1–21.7), and 140 'mild' bleeders (FVIIc 14%, IQR 3–31). The significantly different FVIIc levels, and the decreasing prevalence of homozygotes or double heterozygotes among severe (98%), moderate (84%) and mild (56%) bleeders, further support our classification. The excess of females among moderate bleeders (female/male ratio =2.6) is attributable to menorrhagia. There was no evidence for modulation of clinical features by frequent functional polymorphisms. Homozygotes for the same mutation (Ala294Val; 11125del C) with similar FVIIc and FXa generation levels, showed striking differences in clinical phenotypes. Our study depicts the ample clinical picture of this rare disorder, proposes a severity classification and provides arguments for the early management of the disease in the severe cases. Genotype-phenotype relationships indicate the presence of major environmental and/or extragenic components modulating expressivity of FVII deficiency.
Variability in clinical laboratory practice in testing for disorders of platelet function
Authors: Moffat Karen , Ledford-Kraemer Marlies , Nichols William , Hayward Catherine
Published: February 2005

Disorders of platelet function are important causes of abnormal bleeding that require laboratory tests for diagnosis. Currently there are limited guidelines on how to perform clinical testing for these disorders. The goal of our study was to obtain information on how disorders of platelet function are currently evaluated in clinical laboratories. Two patterns-of-practice surveys were distributed to laboratories of the North American Specialized Coagulation Laboratory Association (NASCOLA). The information collected was analyzed to determine practices and common problems. Forty-seven NASCOLA laboratories participated and 54% completed both surveys. The majority of the laboratories that responded performed more than 50 aggregation tests per year, mainly using platelet rich plasma based methodologies. A minority performed testing for platelet secretion and dense granule abnormalities. While platelet aggregation results were reviewed in various ways, laboratories most commonly issued a combined report containing quantitative values (% aggregation and/or slope) and a qualitative interpretation. Although laboratories used similar agonists for aggregation testing, the final agonist concentrations varied widely. Several approaches were also used to obtain reference intervals. Comments offered by the participants indicated that performing, and interpreting platelet function tests were challenging for many clinical laboratories. Although common practices have evolved, there is considerable variability in the diagnostic test procedures used by clinical laboratories to evaluate disorders of platelet function. These patterns-of-practice surveys illustrate a need for guidelines and recommendations for clinical laboratories performing tests of platelet function.
Stakeholder Influence Strategies: The Roles of Structural and Demographic Determinants
Authors: Frooman Jeff , Murrell Audrey J.
Published: February 2005

Using Frooman’s typology of stakeholder influence strategies, this research examines the strategies that stakeholders select to exert influence on a firm. Using an experimental approach, the responses of actual environmental leaders to a series of hypothetical vignettes were examined. The results of the experiment suggest how both structural and demographic variables can act as determinants of strategy choice along with how these two types of variables may both complement and inhibit one another. Specifically, the results suggest that repertoires of strategies play a critical role in stakeholder behavior. Demographic variables appear to define the repertoires of strategies the stakeholder will typically choose among, whereas structural variables further refine choice from within that repertoire.
Business Ethics and Corporate Governance in Africa
Authors: Rossouw G. J.
Published: February 2005

In recent years there has been a surge in corporate governance reform around the world. On the African continent this phenomenon is evident in the number of national corporate governance reports that have been produced. This article analyzes these national codes of corporate governance in Africa to determine how the relationship between corporate governance and business ethics is being perceived. The article commences by providing a background to the corporate governance reform process that still is in the making in Africa. It then explores the relation between corporate governance and business ethics by looking at various aspects of corporate governance that might have an impact on how business ethics is being perceived and practiced. Finally new corporate governance developments that potentially might have an impact on the prominence and practice of business ethics are reviewed.
Pavlovian Fear Memory Induced by Activation in the Anterior Cingulate Cortex
Authors: Tang Jianrong , Ko Shanelle , Ding Hoi-Ki , Qiu Chang-Shen , Calejesan Amelita A , Zhuo Min
Published: February 2005

Identifying higher brain central region(s) that are responsible for the unpleasantness of pain is the focus of many recent studies. Here we show that direct stimulation of the anterior cingulate cortex (ACC) in mice produced fear-like freezing responses and induced long-term fear memory, including contextual and auditory fear memory. Auditory fear memory required the activation of N-methyl-D-aspartate (NMDA) receptors in the amygdala. To test the hypothesis that neuronal activity in the ACC contributes to unpleasantness, we injected a GABAA receptor agonist, muscimol bilaterally into the ACC. Both contextual and auditory memories induced by foot shock were blocked. Furthermore, activation of metabotropic glutamate receptors in the ACC enhanced behavioral escape responses in a noxious hot-plate as well as spinal nociceptive tail-flick reflex. Our results provide strong evidence that the excitatory activity in the ACC contribute to pain-related fear memory as well as descending facilitatory modulation of spinal nociception.
Polyunsaturated fatty acids interfere with formation of the immunological synapse
Authors: Geyeregger René , Zeyda Maximilian , Zlabinger Gerhard J , Waldhäusl Werner , Stulnig Thomas M
Published: February 2005

Polyunsaturated fatty acids (PUAs) exert inhibitory effects on T cell-mediated immune responses. Activation of T cells in vivo depends on formation of an immunological synapse (IS) at the T cell/antigen-presenting cell (APC) interface. Here, we analyzed effects of PUFA treatment on the formation of the IS and APC-induced human T cell activation. In T cells treated with the PUFA eicosapentaenoic (EPA; 20:5,n-3) and arachidonic acid (20:4,n-6), stimulated by superantigen-presenting cells or APCs, relocalization to the IS of distinct molecules [F-actin, talin, leukocyte functional antigen-1α, clusters of differentiation (CD)3ɛ] was inhibited markedly compared with cells treated with saturated fatty acid, whereas relocalization of protein kinase Cθ to the IS remained unaffected. CD3-induced, sustained phosphorylation of nucleotide exchange factor Vav, which controls cytoskeletal rearrangements underlying IS formation, was significantly reduced in EPA-treated Jurkat and peripheral blood T cells. In addition, T cell raft disruption by methyl-β-cyclodextrin treatment and experiments with a chimeric linker for activation of T cell proteins, which is resistant to PUFA effects on lipid rafts, revealed modifications of lipid rafts as a crucial factor for PUFA-mediated inhibition of APC-stimulated cytoskeletal rearrangements. Furthermore, the efficiency of T cell/APC conjugate formation was significantly reduced with EPA-treated T cells, as was stimulation of CD69 expression, which is not altered following antibody-mediated T cell activation. In conclusion, PUFA treatment of T cells qualitatively and quantitatively alters IS formation, thereby extending T cell signaling defects to pathways that are not intrinsically altered in PUFA-treated T cells when stimulated by antibodies.
LIF/STAT3 controls ES cell self-renewal and pluripotency by a Myc-dependent mechanism
Authors: Cartwright Peter , McLean Cameron , Sheppard Allan , Rivett Duane , Jones Karen , Dalton Stephen
Published: February 2005

Murine ES cells can be maintained as a pluripotent, self-renewing population by LIF/STAT3-dependent signaling. The downstream effectors of this pathway have not been previously defined. In this report, we identify a key target of the LIF self-renewal pathway by showing that STAT3 directly regulates the expression of the Myc transcription factor. Murine ES cells express elevated levels of Myc and following LIF withdrawal, Myc mRNA levels collapse and Myc protein becomes phosphorylated on threonine 58 (T58),triggering its GSK3β dependent degradation. Maintained expression of stable Myc (T58A) renders self-renewal and maintenance of pluripotency independent of LIF. By contrast, expression of a dominant negative form of Myc antagonizes self-renewal and promotes differentiation. Transcriptional control by STAT3 and suppression of T58 phosphorylation are crucial for regulation of Myc activity in ES cells and therefore in promoting self-renewal. Together,our results establish a mechanism for how LIF and STAT3 regulate ES cell self-renewal and pluripotency.
Confidence-Enhanced Performance
Authors: Compte Olivier , Postlewaite Andrew
Published: February 2005

There is ample evidence that emotions affect performance. Positive emotions can improve performance, while negative ones can diminish it. For example, the fears induced by the possibility of failure or of negative evaluations have physiological consequences (shaking, loss of concentration) that may impair performance in sports, on stage, or at school. There is also ample evidence that individuals have distorted recollection of past events and distorted attributions of the causes of success or failure. Recollection of good events or successes is typically easier than recollection of bad ones or failures. Successes tend to be attributed to intrinsic aptitudes or effort, while failures are attributed to bad luck. In addition, these attributions are often reversed when judging the performance of others. The objective of this paper is to incorporate the phenomenon that emotions affect performance into an otherwise standard decision theoretic model and show that in a world where performance depends on emotions, biases in information processing enhance welfare.
Rationalizing the Penn World Table: True Multilateral Indices for International Comparisons of Real Income
Authors: Neary J. Peter
Published: February 2005

Real incomes are routinely compared internationally using methods that “correct” for deviations from purchasing power parity. The most widely used of these is the Geary method which, though theoretically suspect, underlies the Penn World Table. This paper provides a theoretical foundation for the Geary method which I call the GAIA (“Geary-Allen International Accounts”) system. I show that the Geary method is exact when preferences are non-homothetic Leontief and, more generally, gives a (possibly poor) approximation to the GAIA benchmark. An empirical application suggests that both it and other widely used methods underestimate the degree of international inequality.
The Interest Rate, Learning, and Inventory Investment
Authors: Maccini Louis J , Moore Bartholomew J , Schaller Huntley
Published: February 2005

This paper presents a model that provides an explanation, based on regime switching in the real interest rate and learning, of why tests based on stock-adjustment models, Euler equations, or decision rules—which emphasize short-run fluctuations in inventories and the interest rate—are unlikely to uncover a negative relationship between inventories and the real interest rate. The model, however, predicts that inventories will respond to long-run movements, that is, to regime shifts in the real interest rate. Tests emphasizing cointegration techniques confirm this prediction and show a significant long-run relationship between inventories and the real interest rate.
Gibrat's Law for (All) Cities
Authors: Eeckhout Jan
Published: February 2005

Two empirical regularities concerning the size distribution of cities have repeatedly been established: Zipf's law holds (the upper tail is Pareto), and city growth is proportionate. Census 2000 data are used covering the entire size distribution, not just the upper tail. The nontruncated distribution is shown to be lognormal, rather than Pareto. This provides a simple justification for the coexistence of proportionate growth and the resulting lognormal distribution. An equilibrium theory of local externalities that can explain the empirical size distribution of cities is proposed. The driving force is a random productivity process of local economies and the perfect mobility of workers.
Markups, Aggregation, and Inventory Adjustment
Authors: Coen-Pirani Daniele
Published: February 2005

In this paper I suggest a unified explanation for two puzzles in the inventory literature: first, estimates of inventory speeds of adjustment in aggregate data are very small relative to the apparent rapid reaction of stocks to unanticipated variations in sales. Second, estimates of inventory speeds of adjustment in firm-level data are significantly higher than in aggregate data. The paper develops a multi-sector model where inventories are held to avoid stockouts, and price markups vary along the business cycle. The omission of countercyclical markup variations from inventory targets introduces a downward bias in estimates of adjustment speeds obtained from partial adjustment models. When the cyclicality of markups differs across sectors, this downward bias is shown to be more severe with aggregate rather than firm-level data. Similar results apply not only to inventories, but also to labor and prices. Montercarlo simulations of a calibrated version of the model suggest that these biases are quantitatively significant.
Valuing empathy and emotional intelligence in health leadership: a study of empathy, leadership behaviour and outcome effectiveness
Authors: Skinner C , Spurgeon P
Published: February 2005

This article examines the relationship between health managers' self-assessed empathy, their leadership behaviours as rated by their staff, and staff's personal ratings on a range of work satisfaction and related outcome measures. Empathy was conceived of as four distinct but related individual dispositions, namely empathic concern (EC), perspective taking (PT), personal distress (PD) and empathic matching (EM). Results showed three empathy scales (EC, PT and EM) were, as postulated, positively related to transformational behaviour (inspiring followers to achieve more than expected). The same three measures, also as expected, showed no relationship to transactional behaviour (motivating followers to achieve expected results) and were negatively associated with laissez-faire leadership (an absence of leadership style).

Relationships between empathy scales and outcome measures were selective and moderate in size. Strongest empathy association was evident between the PT scale and most outcome measures. Conversely, the extra effort outcome appeared most sensitive to the range of empathy scales. Where significant relationships did exist between empathy and outcome, leadership behaviour was in all cases a perfect mediator. Whilst not denying the smaller dispositional effects on leadership outcomes, leadership behaviour itself, rather than individual traits such as empathy, appear to be major influencing factors in leadership effectiveness.
The effects of Medicare Health Management Organizations on hospital operating profit in Florida
Authors: Large John T , Sear Alan M
Published: February 2005

Between 1992 and 1997, the number of members enrolled in Medicare Health Management Organizations (HMOs) nationwide in the USA more than doubled. During this period, managed care organizations wielded considerable influence over the health care of a large segment of the Medicare population in Florida. This study examined the impact on operational profit of 148 short-term, acute-care Florida hospitals in this period from Medicare HMO patients, as part of a hospital's payer mix. Three measures of hospital profitability were used: operating profit per actual bed, total operating profit with no adjustment for bed size, and operating margins. The multivariate statistical model employed in this study was a linear mixed model with an autoregressive order one (AR[1]) parametric structure on the covariance matrix.

The results of the study indicate that Florida hospitals experienced greater profit pressures from Medicare HMO inpatients than from traditional Medicare inpatients. Further, these hospitals could have experienced positive profit effects with greater traditional Medicare participation and negative financial effects with greater Medicare HMO participation. Additionally, Medicare HMO patients appear to have been admitted to hospitals in worse health condition than those in traditional Medicare. Medicare HMO patients were more likely to have used emergency rooms as the source of admission than traditional Medicare patients. Also, Medicare HMO patients were more likely to have been admitted as emergent cases than traditional Medicare patients. Other research has shown that Medicare HMO patients, at the time of enrolment, are probably healthier than traditional Medicare enrollees, but here they appear to have been admitted to hospitals with higher levels of severity of illness. Explanations are offered for these findings.
Integrated primary care organizations: to what extent is integration occurring and why?
Authors: Simoens Steven , Scott Anthony
Published: February 2005

Integration in primary health care is occurring in many health-care systems without a clear understanding of the meaning of integration, its form and rationale. This literature review examines the definition and extent of integration, as well as the factors that might encourage it in the context of British integrated primary care organizations (IPCOs). Integration is complex and multifaceted. No commonly agreed definitions of integration have been developed and the range of dimensions examined in the empirical literature was limited. However, some of the dimensions examined in studies of IPCOs may be useful in better understanding the form integration takes. Few studies were designed to examine the determinants of integration or were explicitly based on theory. Research showed that the level of production and transaction costs was not related to the size of the IPCO, although in practice the attitudes of health professionals are likely to be more important influences on the extent of integration. To date, little progress has been made in explaining and measuring integration. If further integration in primary health care is warranted, more research is required to understand its nature, form and rationale.
The structure of an enzyme-activating fragment of human telomerase RNA
Authors: LEEPER THOMAS C. , VARANI GABRIELE
Published: February 2005

The ribonucleoprotein enzyme telomerase ensures the stability and fidelity of linear chromosome ends by elongating the telomeric DNA that is lost during each round of DNA replication. All telomerases contain a catalytic protein component homologous to viral reverse transcriptases (TERT) and an RNA (TR) that provides the template sequence, acts as the scaffold for ribonucleoprotein assembly, and activates the enzyme for catalysis. Vertebrate telomerase RNAs contain three highly conserved structural and functional domains: the template domain, the “CR4-CR5” or “activation” domain essential for activation of the enzymatic activity, and a 3′-terminal “box H/ACA”–homology domain responsible for ribonucleprotein assembly and maturation. Here we report the NMR structure of a functionally essential RNA structural element derived from the human telomerase RNA CR4-CR5 domain. This RNA, referred to as hTR J6, forms a stable hairpin interrupted by a single nucleotide bulge and an asymmetric internal loop. Previous work on telomerase has shown that deletion of the hTR J6 asymmetric internal loop results in an RNA incapable of binding the enzymatic protein component of the RNP and therefore an inactive RNP without telomerase activity. We demonstrate here that the J6 internal loop introduces a twist in the RNA structure that may position the entire domain into the catalytic site of the enzyme.
Analysis of Factors Influencing the Shear Deformation of Granular Materials
Authors: Assaad A , Masad E
Published: February 2005

This study utilizes recent advances in image analysis techniques to conduct detailed multiscale shape analysis of four granular materials. In addition, X-ray analysis was used to measure the chemical composition of these granular materials. The shape and chemical composition results were used to investigate the factors influencing the shear deformation of granular materials tested using the direct shear device. The analysis involved determining the different energy components influencing the shear deformation of granular materials.

The results show that the granular material angularity and texture are two different distinct properties that can be quantified accurately using the methods proposed in this paper. Texture influences the material “true” friction,” while angularity mostly affects the dilative behavior of the materials. The results also show that the energy dissipated in particle rearrangement is an important factor that should be considered in the analysis of shear deformation of granular materials. This dissipated energy increases with an increase in material angularity and a decrease in confinement. A relationship between the various components of the angle of internal friction and stress confinement is proposed in this study.
A Cylinder Shear Apparatus
Authors: Corfdir A , Lerat P , Vardoulakis I
Published: February 2005

Studies of the interface between soil and an element of structure are actively carried out, considering the importance of the behavior of such interfaces in civil engineering applications such as deep foundations, retaining structures, and soil reinforcement. In the past a wide variety of different testing devices have been used, such as the modified direct or simple shear apparatus, pull-out devices, and annular shear apparatuses. Here a new shear device, the cylinder shear apparatus, is presented that has been designed to enhance our shear testing possibilities. This new shear device allows, as ring shear devices, significant shear displacements with an improved homogeneity of the interface. It allows also the control of the normal confining stress, stress control in a direction parallel to the interface, and visualization of the interface kinematics. The cylinder shear apparatus gives also the possibility of performing tests with natural granular material and/or with Schneebeli's rollers, with dry, saturated, drained and undrained samples and continuous pore fluid pressure monitoring.
Evaluation of the Base Condition of Drilled Shafts by the Impact-Echo Method
Authors: Soo KD , Woo KH
Published: February 2005

Numerical and experimental model studies were carried out to evaluate the base condition of drilled shafts. Base conditions such as free, fixed, rock-socketed, and soft-bottom were considered. To simulate the base conditions, mock-up shaft models made of cement mortar were used. The impact-echo method was applied to evaluate each base condition. Finally, field tests were performed for the rock-socketed shafts. It is found that the rock-socketed condition and socketed length can be evaluated. The soft bottom condition can be identified, only when the side contact between shaft and surrounding rock is poor, whereas it cannot be identified when the side contact is good.
Effect of Presence of Rigid Base within the Soil on the Dynamic Response of Rigid Surface Foundation
Authors: Mandal A , Baidya DK
Published: February 2005

The present experimental investigations study the effect of presence of rigid base at any depth within the soil mass on the dynamic response of foundation under vertical mode of vibration. Model block vibration tests on rigid surface footing are conducted on a different soil layer of finite thicknesses underlain by a rigid base. A concrete block of size 400 × 400 × 100 mm is used as the model block, and a Lazan type mechanical oscillator is used for inducing vibration in vertical direction. The finite soil layers of different thicknesses are prepared in a pit at the bottom of which a massive concrete layer of 300 mm thick was cast to represent it as a rigid base. In the investigation two different soils, namely, local in situ soil and sand are used. In total 72 tests are conducted in different loading combinations and soil types, and several important observations are reported. Two different methods are proposed to analyze the dynamic response of a foundation resting on a finite layer underlain by a rigid layer. Finally, the experimental results are compared with the results that were obtained by the proposed method. A Mass-Spring-Dashpot (MSD) model with proper consideration of damping factor is found to provide reasonably accurate results. Elastic Half Space Theory (EHST) with equivalent soil properties is found to underestimate the displacement amplitude.
Use of EPS Grains to Simulate the Behavior of MSW in Simple Shear
Authors: Simonini P , De Ronch M
Published: February 2005

The difficulty in laboratory testing of highly heterogeneous municipal solid waste (MSW) may suggest an investigation of the influence of different stress/strain/drainage conditions, and use of an analogical equivalent medium such as assemblies of expanded polystyrene (EPS) grains, which are characterized by a mechanical response very similar to MSW but relatively simpler for testing preparation. Both materials, in fact, evidently show a behavioral analogy, such as a different response when subjected to triaxial compression or pure shear, resulting from the effects of significant porosity and a relevant inherent compressibility of the individual elements.

This research is concerned with an experimental investigation into the behavior of saturated assemblies of EPS grains, tested in the laboratory using a modified simple shear device. In addition to the description of the experimental testing technique, this paper attempts to discuss the main outcome of test results, showing particularly the influence of inherent compressibility of EPS grains on material volumetric response.
Triaxial Testing System for Measuring Loading-Rate Effects During Cyclic Tests of Sand
Authors: Hoque E , Tatsuoka F
Published: February 2005

A triaxial testing system is described for obtaining reliable data for measuring stiffness and damping of a sand by applying cyclic load in the frequency range between 0.005 and 2.0 Hz. The system is equipped with LDTs to measure axial deformations locally, gap sensors (GSs) to measure axial and radial deformations, and a load-cell. The data acquisition units of these components were critically examined for the possible existence and the influences of time lag in the stress-strain responses of cyclic load. For the measurement of a pair of corresponding stress and strain, data acquisition systems consisting of various electronic transducers must be identical to each other. Damping ratio evaluated with axial strain by the inductive-type sensor GS was found unreliable when used with a strain-gage type load cell to measure deviator stress. The problem was totally absent in the pair of load cell and LDTs as they are strain-gage type devices having similar data acquisition units. Using the latter combination, the stiffness was observed independent of frequency, while damping showed noticeable dependency on the frequency of loading.
Comparative Statistical Analysis of Original and Aged Bituminous Material Viscosity
Authors: Divinsky M
Published: February 2005

Statistical behavior and peculiarities of the viscosity data for original and aged bituminous materials have been investigated. Approximation of the empirical distribution of the aging index values as the ratio of corresponding values for aged and original bituminous material viscosity has been carried out employing normal, lognormal, and Charlier theoretical distribution models. Corresponding models for the suitable approximation of values under consideration have been verified. Probability distribution models under discussion reflect the main features of the aging index data. Accordance of the applied distribution models has been confirmed by transformed-values analysis employing logarithmic and square root transformations for presented aging index values. Suggested probabilistic models including the normal distribution and, in the first instance, the lognormal and Charlier distribution models, can be recommended for practical application for corresponding data analysis. Relationships among the viscosity data of original and aged bituminous materials employing different linear and nonlinear equations and multiple regression models, also including use of penetration and kinematic viscosity data, have been studied and analyzed. Specifications of the residual behavior for the regression equations have been examined, keeping in mind data peculiarities and their degree of heterogeneity. Presented results widen the possibilities for original and aged bituminous materials penetration and aging index data interpretation, increasing the reliability of estimations for corresponding quantitative characteristics.
Mechanical Behavior of Polymers PBXW-128 and PBXN-110 Under Uniaxial and Multiaxial Compression at Different Strain Rates and Temperatures
Authors: Çolak ÖÜ
Published: February 2005

The influence of strain rate, temperature, and confining pressure on the mechanical behavior of PBXN-110 binder “inert” (hydroxy-terminated polybutadiene (HTPB)) and PBXW-128 simulant “inert,” which is mixed with small particles of sugar, approximately 50 % by weight, is presented in this paper. The polymer PBXN-110 is used as the matrix for the particle-reinforced polymer composite (PBXW-128); the latter is the mock or inert equivalent of actual explosive material. Stress-strain response of both polymeric materials under uniaxial compression is found to be dependent on the strain rate. On one hand, it is observed that PBXW-128 exhibits temperature-dependent behavior, while the mechanical response of PBXN-110 is not significantly affected at temperatures above the glass transition temperature. Compression experiments in the presence of confining pressure reveal that the stress-strain response of each material is rate insensitive.