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Second Period (second + period)
Selected AbstractsMetropolitan Open-Space Protection with Uncertain Site AvailabilityCONSERVATION BIOLOGY, Issue 2 2005ROBERT G. HAIGHT acceso público; Chicago; modelo de selección de sitio; optimización; representación de especies Abstract:,Urban planners acquire open space to protect natural areas and provide public access to recreation opportunities. Because of limited budgets and dynamic land markets, acquisitions take place sequentially depending on available funds and sites. To address these planning features, we formulated a two-period site selection model with two objectives: maximize the expected number of species represented in protected sites and maximize the expected number of people with access to protected sites. These objectives were both maximized subject to an upper bound on area protected over two periods. The trade-off between species representation and public access was generated by the weighting method of multiobjective programming. Uncertainty was represented with a set of probabilistic scenarios of site availability in a linear-integer formulation. We used data for 27 rare species in 31 candidate sites in western Lake County, near the city of Chicago, to illustrate the model. Each trade-off curve had a concave shape in which species representation dropped at an increasing rate as public accessibility increased, with the trade-off being smaller at higher levels of the area budget. Several sites were included in optimal solutions regardless of objective function weights, and these core sites had high species richness and public access per unit area. The area protected in period one depended on current site availability and on the probabilities of sites being undeveloped and available in the second period. Although the numerical results are specific for our study, the methodology is general and applicable elsewhere. Resumen:,Planificadores urbanos adquieren espacios abiertos para proteger áreas naturales y proporcionar acceso público a oportunidades de recreación. Debido a presupuestos limitados y a la dinámica de los mercados de terrenos, las adquisiciones se llevan a cabo secuencialmente en función de la disponibilidad de fondos y sitios. Para atender estas características de la planificación, formulamos un modelo de selección de sitios de dos períodos con dos objetivos: maximizar el número esperado de especies representado en sitios protegidos y maximizar el número esperado de personas con acceso a sitios protegidos. Ambos objetivos fueron maximizados con un límite superior en la superficie protegida en los dos períodos. El balance entre la representación de especies y el acceso público fue generado por el método de ponderación de programación de multiobjetivos. La incertidumbre fue representada con un conjunto de escenarios probabilísticos de la disponibilidad de sitios en una formulación lineal-integral. Para demostrar el modelo, utilizamos datos para 27 especies raras en 31 sitios potenciales en el oeste del Condado Lake, cerca de la ciudad de Chicago. Cada curva tenía forma cóncava y la representación de especies descendió a medida que incrementó la accesibilidad pública, con un menor equilibrio en niveles altos del presupuesto para el área. Varios sitios fueron incluidos en soluciones óptimas independientemente de las funciones de ponderación de los objetivos, y estos sitios tuvieron alta riqueza de especies y acceso público por unidad de área. La superficie protegida en el período uno dependió de la disponibilidad de sitios y de las probabilidades de que los sitios no fueran desarrollados y de su disponibilidad en el segundo período. Aunque los resultados numéricos son específicos a nuestro estudio, la metodología es general y aplicable en otros sitios. [source] Cell proliferation in the developing lateral line system of zebrafish embryosDEVELOPMENTAL DYNAMICS, Issue 2 2005Laurent Laguerre Abstract The sensory organs of the embryonic lateral line system are deposited by migrating primordia that originate in the otic region. Here, we examine the pattern of cell proliferation in the posterior lateral line system. We conclude that three phases of cell proliferation are involved in the generation of this system, separated by two phases of mitotic quiescence. The first phase corresponds to generalized proliferation during gastrulation, followed by a first period of quiescence that may be related to the determination of the lateral line precursor cells. A second phase of proliferation takes place in the placode and migrating primordium. This region is organized in annuli that correspond to the expression of proneural/neurogenic genes. A second period of quiescence follows, corresponding to deposition and differentiation of the sensory organs. The third period of proliferation corresponds to continued renewal of hair cells by division of support cells within each sensory organ. Developmental Dynamics 233:466,472, 2005. © 2005 Wiley-Liss, Inc. [source] The destinies of the low- and middle-income country submissionsACTA PSYCHIATRICA SCANDINAVICA, Issue 4 2007J. Konradsen Objective:, To measure the number of submissions to Acta Pyschiatrica Scandinavica from low- and middle-income countries (LIC/MIC) compared with submissions from high income countries (HIC), to compare the way through the peer review process for the three groups respectively, as well as how they do as published articles eventually. Method:, By help of the Acta Psychiatrica Scandinavica editorial office database all submissions of reviews of the literature, clinical overviews, original articles, brief communications, and case reports from 2002 through 2005 were analysed as to external/in-house review, acceptance/rejection, number of downloads from Blackwell-Synergy, and number of citations [Institute of Scientific Information (ISI)] in a comparison between HIC and LIC/MIC. Results:, About 14.6% of the total submissions in 2002/2003 came from LIC and MIC countries, 15.5% for the 2004/2005 period. In both periods, a larger portion of LIC/MIC manuscripts were reviewed exclusively in-house compared with HIC ones and among those papers reviewed by external experts a smaller proportion of the submissions from HIC countries were rejected than of those from LIC and MIC countries. From the first to the second period there is a significant increase of proportion of submitted LIC/MIC papers accepted for publication compared with HIC papers. Full text download and citation statistics did not differ significantly between HIC and LIC/MIC. Conclusion:, Low- and middle-income countries manuscripts do gradually better in the competition with HIC papers in Acta Psychiatrica Scandinavica. The major observation is that the total number of LIC/MIC submissions to the journal is still low. [source] The role of Late Holocene climate variability in the expansion of yellow birch in the western Great Lakes regionDIVERSITY AND DISTRIBUTIONS, Issue 5 2002Stephen T. Jackson Abstract. Pollen records from the western Great Lakes region of North America show substantial increases in birch pollen percentages during the late Holocene. The vegetational and population dynamics underlying the birch increase have received little attention, in part because of the inability to discriminate among species of birch based on pollen morphology. We used analyses of pollen and plant macrofossils from four lakes in the Upper Peninsula of Michigan to document that the birch pollen increase represents a regional expansion of yellow birch (Betula alleghaniensis) populations, which was initiated c. 4500 years ago. Whether yellow birch invaded the region at this time or simply expanded from small, previously established populations is not clear, although it probably did not grow near our study sites before the expansion. The initial expansion occurred during an independently documented period of high moisture and high water levels in Lake Michigan. A subsequent expansion in yellow birch abundance and distribution occurred c. 3000 years ago, coinciding with a second period of increased moisture and high lake-levels. The yellow birch expansion may have been modulated by millennial-scale climate variability, with most rapid expansion occurring during relatively wet periods. [source] The eigenvalues of isolated bridges with transverse restraints at the end abutmentsEARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS, Issue 8 2010Nicos Makris Abstract This paper examines the eigenvalues of multi-span seismically isolated bridges in which the transverse displacement of the deck at the end abutments is restricted. With this constraint the deck is fully isolated along the longitudinal direction, whereas along the transverse direction the deck is a simple-supported beam at the end abutments which enjoys concentrated restoring forces from the isolation bearings at the center piers. For moderate long bridges, the first natural period of the bridge is the first longitudinal period, while the first transverse period is the second period, given that the flexural rigidity of the deck along the transverse direction shortens the isolation period offered by the bearings in that direction. This paper shows that for isolated bridges longer than a certain critical length, the first transverse period becomes longer than the first longitudinal period despite the presence of the flexural rigidity of the deck. This critical length depends on whether the bridge is isolated on elastomeric bearings or on spherical sliding bearings. This result is also predicted with established commercially available numerical codes only when several additional nodes are added along the beam elements which are modeling the deck in-between the bridge piers. On the other hand, this result cannot be captured with the limiting idealization of a beam on continuous distributed springs (beam on Wrinkler foundation),a finding that has practical significance in design and system identification studies. Finally, the paper shows that the normalized transverse eigenperiods of any finite-span deck are self-similar solutions that can be represented by a single master curve and are independent of the longitudinal isolation period or on whether the deck is supported on elastomeric or spherical sliding bearings. Copyright © 2009 John Wiley & Sons, Ltd. [source] Walking and Talking as Predictors of Falls in the General Population: The Leiden 85-Plus StudyJOURNAL OF AMERICAN GERIATRICS SOCIETY, Issue 10 2003Annetje Bootsma-van der Wiel MD Objectives: To compare the value of dual tasking in predicting falling in the general population of oldest old with that of easy-to-administer single tasks. Design: Prospective population-based follow-up study. Setting: Municipality of Leiden, the Netherlands. Participants: Representative cohort of 380 individuals, all aged 85 at baseline. Measurements: During enrollment, walking time over a 12-meter distance was measured, as well as the verbal fluency to recite names of animals or professions during a 30-second period. In the dual task, performance was assessed when participants combined walking with reciting names. Incidence of falls and fractures was assessed by interviewing participants and checking their medical histories. Results: After 1 year of follow-up, 42% of the participants reported one or more falls, and 4% suffered a fracture. Total walking time, number of steps, and verbal fluency were all strongly related to incident falls (P for trend for all <.01), but dual-task performance was not a better predictor for incident falls than single-task performance. Conclusion: The dual-task test in this study had no predictive value above that of a single-task test to predict falling. Dual tasks with more-sensitive measures of impaired dual-task execution might have better test characteristics. In this study, history of falls and performance on an easy-to-administer single walking task identified old persons at higher risk for falling who could benefit from fall preventive strategies. [source] Mineralization improvement of phenol aqueous solutions through heterogeneous catalytic ozonationJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 12 2003Fernando J Beltrán Abstract To assess the mineralization level achieved, aqueous solutions of phenol have been treated with ozone in the presence of different solid catalysts. Activated carbon was the principal catalyst investigated, although some additional experiments were carried out by utilizing metal oxide-based catalysts (ie Ti, Co and Fe) supported onto alumina. Usage of Co/Al2O3 led to the highest values of phenol byproduct mineralization, nevertheless some metal leaching was experienced in the process. The operating variables studied when using activated carbon as the catalyst were ozone gas concentration, amount of catalyst added and temperature. Regardless of the catalyst type used, two different ozonation kinetic regimes were observed: (I) an initial period, corresponding to the presence of phenol in solution, characterized by small amounts of dissolved ozone and no improvement of the mineralization degree if comparing catalytic and non-catalytic runs; (II) a second period, free of phenol, in which dissolved ozone accumulated in water and the beneficial effects of catalysts on mineralization were noticed. Experimental data also demonstrated the improvement in oxalic acid elimination in the presence of heterogeneous catalysts. Finally, consumption of ozone per mass of carbon removed, reaction factors and Hatta numbers were also calculated. Copyright © 2003 Society of Chemical Industry [source] Conditionality covenants: Commitment versus discretion in sovereign credit contractsJOURNAL OF INTERNATIONAL DEVELOPMENT, Issue 4 2010Sherif Khalifa Abstract This paper investigates the impact of imposing conditionality covenants on the performance of the signatories to a sovereign credit contract. A two period model is developed in which creditors provide a loan to a sovereign conditional upon the implementation of investments. Commitment to these covenants overcome the debt repudiation problem, as it increases the likelihood of repayment, if the implemented conditionalities contribute to an increase in the sovereign's productive capacity. A three period model is also developed to entertain the possibility that the sovereign engage in credit activities in subsequent periods, where in the final period the debtor has obligations towards junior and senior creditors. This allows for dynamic inconsistency, as the sovereign may be tempted to increase its debt in the second period, thus increasing the probability of repudiation in the third period. Imposing conditionality covenants by senior creditors that increase the portion they can appropriate in case of repudiation, relative to junior creditors, reduces the supply of credit by junior creditors in the second period and thus overcomes the debt dilution problem. Copyright © 2009 John Wiley & Sons, Ltd. [source] Time Consistent Optimal Redistribution Policy in an Overlapping Generations ModelJOURNAL OF PUBLIC ECONOMIC THEORY, Issue 1 2004Oliver Lorz This paper analyzes optimal redistribution policy in a two-period version of the overlapping generations model with heterogeneous individuals and asymmetric information between the government and the private sector. The government of the first period determines redistribution transfers for the first period but is not able to set the policy variables for the second period. With respect to savings the paper considers two scenarios: In the first scenario savings are observable and the government can set individual savings levels in addition to redistributive transfers. In the second scenario savings and capital incomes are not observable. In both cases the redistribution equilibrium is not second-best efficient. [source] Effects of a combination of napping and bright light pulses on shift workers' sleepiness at the wheel: a pilot studyJOURNAL OF SLEEP RESEARCH, Issue 4 2009DAMIEN LEGER Summary To assess the effects of napping + bright light on shift work drivers sleepiness at the wheel, we performed a pilot study on nine shift workers on three shifts (morning, afternoon, night), driving on a private road circuit. Sleepiness at the wheel was measured by ambulatory polysomnography and assessed using 30-s segments of recordings with a percentage of theta electroencephalogram of at least 50% (15 s) of the period recorded. Sleepiness was also assessed by the Stanford Sleepiness Scale (SSS). Participants drove the same car on two similar 24-h periods of work, with three drivers in each shift (morning, afternoon, night), separated by 3 weeks. During the baseline period, the subjects were told to manage their rest as usual. During the second experimental period, they had to rest lying in a dark room with two naps of 20 min and then exposed to bright light (5000 lux) for 10 min. Subjects showed a significantly decreased sleepiness at the wheel with an average of 10.7 ± 6.7 episodes of theta sleep during the baseline (766 ± 425 s) versus 1.0 ± 1.0 episode lasting 166 ± 96 s during the second period (P = 0.016; P = 0.0109). The percentage of driving asleep was also significantly reduced (3.7% ± 1.9% versus 0.9% ± 0.6%, P = 0.0077). The average SSS score in the group decreased from 2.76 ± 1.27 to 2.28 ± 0.74 (P = 0.09). In this pilot and preliminary study, a combination of napping and bright light pulses was powerful in decreasing sleepiness at the wheel of shift work drivers. [source] Recombinant activated factor VII efficacy and safety in a model of bleeding and thrombosis in hypothermic rabbits: a blind studyJOURNAL OF THROMBOSIS AND HAEMOSTASIS, Issue 2 2007A. GODIER Summary.,Background:,Recombinant activated factor VII (rFVIIa) is increasingly used to secure hemostasis in hemorrhagic situations in trauma and surgical patients. Hypothermia is often observed in these clinical settings. Objective:,To study the efficacy and safety of rFVIIa in hypothermia in a rabbit model of bleeding and thrombosis. Methods:,Sixty-nine rabbits were anesthetized, ventilated and monitored for blood pressure, temperature and carotid flow. The Folts model was used: a stenosis (75%) and an injury were carried out on the carotid artery, inducing thrombosis. Blood flow decreased as thrombus size increased until the pressure gradient was such that the thrombus was released and local arterial blood flow was suddenly restored. This is known as a cyclic flow reduction (CFR). After counting baseline CFRs during a 20-min period (P1), rabbits were randomized blindly to one of four groups: normothermic (NT) placebo or rFVIIa (150 ,g kg,1), hypothermic (HT) (34 °C) placebo or rFVIIa. Then CFRs were recorded over a second period (P2). At the end of the experiment, a hepato-splenic section was performed and the amount of blood loss was recorded. After each period, the following were measured: ear immersion bleeding time (BT), hemoglobin, platelet count, prothrombin time (PT), activated partial thromboplastin time (aPTT) and fibrinogen. Results:,Hypothermia increased BT and blood loss. These effects were reversed by rFVIIa. In NT rabbits, rFVIIa shortened BT but did not reduce blood loss. rFVIIa-treated rabbits bled similarly regardless of temperature. The incidence of CFRs was higher in treated than placebo animals regardless of temperature. rFVIIa decreased PT and aPTT without modifying platelet count or fibrinogen level. Conclusion:,Hemostatic efficacy of rFVIIa was maintained in hypothermia. However, the number of CFRs was higher in the rFVIIa-treated group than in the placebo groups, whether for NT or HT rabbits. [source] Planned obsolescence and marketing strategyMANAGERIAL AND DECISION ECONOMICS, Issue 8 2000Atsuo Utaka By using a two-period model of a durable goods monopolist, we investigate marketing activities that have an obsolescence effect on products already sold in the past period. We assume that the monopolist can stimulate consumer demand for second-period products by marketing activities, and analyse not only the case where the level of marketing is determined in the second period, but also the case where it is determined in advance, namely, in the first period. It is shown that the equilibrium level of marketing becomes higher than the efficiency level not only in the former case, but also in the latter case if the obsolescence effect is not so large. Copyright © 2000 John Wiley & Sons, Ltd. [source] Flexible supply contracts for short life-cycle goods: The buyer's perspectiveNAVAL RESEARCH LOGISTICS: AN INTERNATIONAL JOURNAL, Issue 1 2002Joseph M. Milner In this paper we analyze a two-period supply contract which allows for order adjustment by the buyer. The buyer is required to place orders for two periods. After observing initial demand, the buyer is then allowed to adjust the second order, paying a per unit order adjustment penalty. We describe the optimal behavior of the buyer under such a contract, both in determining the initial order quantities and in subsequently adjusting the order. We compare the solution to a contract where no adjustment is allowed and to the case where adjustment is allowed without penalty. We demonstrate that flexible contracts can reduce the potentially negative effect of correlation of demand between two periods. Further, we investigate how the duration of the first period vis-à-vis the second period affects the profitability of the buyer as a function of the degree of correlation. © 2002 John Wiley & Sons, Inc. Naval Research Logistics, 49: 25,45, 2002; DOI 10.1002/nav.10002 [source] Randomised controlled trial of the effects of two rigid gas permeable (RGP) contact lens materials and two surface cleaners on straylight valuesOPHTHALMIC AND PHYSIOLOGICAL OPTICS, Issue 5 2009Marten F. Fortuin Abstract Purpose:, In a double-masked randomized controlled crossover study we investigated both the retinal responses to straylight, and the effects of lens cleaners on straylight values, in two different RGP contact lens materials. Methods:, Thirty patients (20,59 years) wearing RGP lenses were refitted with new lenses made of Boston XO material in one eye and made of Comfort O2 (ONSI-56) material in the other eye. Reported wetting angles for the Boston XO material (103°) and for the ONSI-56 material (7.2°) were obtained by sessile drop measurements. After refitting, the study comprised three 5-week trial periods. In Period 1 half of the participants (Group A) wore Boston XO lenses in their right eye and Comfort O2 (ONSI-56) lenses in their left eye, and the other half (Group B) vice versa. In Period 2 Group A wore Comfort O2 (ONSI-56) lenses in their right eye and Boston XO lenses in their left, and Group B vice versa. All participants used Miraflow cleaner during periods 1 and 2. In Period 3, during which all participants used Boston cleaner, Group A wore Boston XO lenses in their right eye and Comfort O2 (ONSI-56) lenses in their left eye and Group B vice versa. Straylight data (log S) were obtained with and without contact lenses using the Oculus C-Quant straylight meter in all three periods. Central corneal thickness (CCT) was measured in the second and third periods. Results:, When not wearing lenses (n = 60 eyes) at the end of the second 5 week trial period straylight was measured twice with averages of 1.07 log S, and the corrected CCT measurements averaged 546 ,m. Straylight values with Comfort O2 (ONSI-56) reached 1.15 log S at the end of both the second (n = 25 eyes) and third periods (n = 23 eyes). Straylight values with Boston XO were 1.17 log S (n = 26 eyes) at the end of the second period, and 1.16 log S (n = 25 eyes) at the end of the third period. Conclusions:, Existing RGP lens wearers refitted with new lenses with different contact angles, made of Boston XO and Comfort O2 (ONSI-56) showed, over three 5 week periods, relatively small increases in straylight, which were functionally comparable, irrespective of the type of lens material or lens cleaner used. At every visit, straylight values and CCTs returned to baseline levels after RGP lens removal, confirming that the straylight fluctuations were mainly due to scattering from the RGP lenses; or tear film interaction; or a combination of both. [source] QT Interval Variability and Adaptation to Heart Rate Changes in Patients with Long QT SyndromePACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 1 2009JAN N, MEC M.D. Background: Increased QT variability (QTV) has been reported in conditions associated with ventricular arrhythmias. Data on QTV in patients with congenital long QT syndrome (LQTS) are limited. Methods: Ambulatory electrocardiogram recordings were analyzed in 23 genotyped LQTS patients and in 16 healthy subjects (C). Short-term QTV was compared between C and LQTS. The dependence of QT duration on heart rate was evaluated with three different linear models, based either on the RR interval preceding the QT interval (RR0), the RR interval preceding RR0 (RR -1), or the average RR interval in the 60-second period before QT interval (mRR). Results: Short-term QTV was significantly higher in LQTS than in C subjects (14.94 ± 9.33 vs 7.31 ± 1.29 ms; P < 0.001). It was also higher in the non-LQT1 than in LQT1 patients (23.00 ± 9.05 vs 8.74 ± 1.56 ms; P < 0.001) and correlated positively with QTc in LQTS (r = 0.623, P < 0.002). In the C subjects, the linear model based on mRR predicted QT duration significantly better than models based on RR0 and RR -1. It also provided better fit than any nonlinear model based on RR0. This was also true for LQT1 patients. For non-LQT1 patients, all models provided poor prediction of QT interval. Conclusions: QTV is elevated in LQTS patients and is correlated with QTc in LQTS. Significant differences with respect to QTV exist among different genotypes. QT interval duration is strongly affected by noninstantaneous heart rate in both C and LQT1 subjects. These findings could improve formulas for QT interval correction and provide insight on cellular mechanisms of QT adaptation. [source] Klimapolitik: Kyoto-Protokoll und Emissionshandel für CO2 -Zertifikate in der EU1PERSPEKTIVEN DER WIRTSCHAFTSPOLITIK, Issue 3 2005Wolfgang Ströbele Also every economist knows that the institutional conditions and the rules of the game are important. This basic idea stood behind the introduction of a CO2 -emissions trading system within the European Community starting in 2005. Since the starting point is the Kyoto-protocol with its subset of relevant states involved and the rules agreed upon there, one must ask whether the EU CO2-trading system is really an instrument that helps to reach the Kyoto goals more efficiently. A positive answer to this question is very doubtful. The new European subsystem is only valid for CO2 while Kyoto knows six greenhouse gases, the EU trading periods are 2005,2007 and 2008,2012 while Kyoto is only relevant for the second period, the integration with all flexible instruments of Kyoto is not guaranteed from the beginning. The plants involved are power plants and plants with high energy intensity. Since the technological levels of these plants are rather similar in Europe, the difference in marginal abatement cost will not be large enough to offset the rather high transaction cost of the special EU system. Furthermore, the heating systems and small scale plants of industry are not included in the trading system. The same holds true for traffic, households and the service sector. Drawing a borderline between CO2 -policy there and the trading activities will cause inefficiencies. If CO2 -prices are high, the main incentive of the trading system will be a large shift from domestic production to production abroad without any CO2 -restrictions. Leakage-effects will then be dominant. With low CO2 -prices the special European bureaucratic system will not create enough efficiency gains to cover the trading system's cost. [source] Actigraphic assessment of the circadian rest,activity rhythm in elderly patients hospitalized in an acute care unitPSYCHIATRY AND CLINICAL NEUROSCIENCES, Issue 1 2003Stéphane Vinzio RD Abstract Hospitalization for acute illness is a major risk factor of rest,activity rhythm disturbance among elderly subjects. The rest,activity rhythm is disturbed by the acute illness, aging and hospital environment. The purpose of this study is to assess the rest,activity rhythm and light exposure (using a wrist worn actigraph) of 10 patients (mean age 81 years, seven females) admitted on an acute care unit, suffering from cardiac, respiratory or renal acute disease. A non-parametric method was used to analyze activity data. With an improvement of the underlying diseases, the mean relative amplitude of rhythm increased from 0.31 ± 0.19 for the first 5-day period after admission to 0.54 ± 0.21 for the second period before discharge (P < 0.05). The amount of time at night spent above a lighting threshold of 50 lux decreased from 31.4 to 12.3 min between the two periods. The rhythm of elderly subjects hospitalized in the acute care unit is severely altered during the initial period and is progressively resynchronized following clinical improvement. Under the acute underlying disease and/or aging, environmental conditions (light, noise) should be considered to maintain regular rest,activity rhythm. [source] Liquidity risk and the hedging role of optionsTHE JOURNAL OF FUTURES MARKETS, Issue 8 2006Kit Pong Wong This study examines the impact of liquidity risk on the behavior of the competitive firm under price uncertainty in a dynamic two-period setting. The firm has access to unbiased one-period futures and option contracts in each period for hedging purposes. A liquidity constraint is imposed on the firm such that the firm is forced to terminate its risk management program in the second period whenever the net loss due to its first-period hedge position exceeds a predetermined threshold level. The imposition of the liquidity constraint on the firm is shown to create perverse incentives to output. Furthermore, the liquidity constrained firm is shown to purchase optimally the unbiased option contracts in the first period if its utility function is quadratic or prudent. This study thus offers a rationale for the hedging role of options when liquidity risk prevails. © 2006 Wiley Periodicals, Inc. Jrl Fut Mark 26:789,808, 2006 [source] Preoperative Functional Assessment of Auditory Cortex in Adult Cochlear Implant Users,,THE LARYNGOSCOPE, Issue 1 2001Peter S. Roland MD Abstract Objectives To e-plore functional neuroanatomical responses to auditory stimulation before and after implantation. Study Design A prospective study of three cochlear implant candidates (pure-tone averages of 90 dB HL or greater bilaterally and hearing in noise test [HINT] performances of <40%) in which regional cerebral blood flow (rCBF) was assessed using single photon emission computed tomography (SPECT). Methods Candidates watched a 15-minute videotaped story under four conditions: audio presented monaurally in the right and left ears (aided), audio presented binaurally (aided), and visual-only presentation of the story. Five minutes into each story, 20 to 25 mCi of technetium 99m (99mTc) hexamethyl-propyleneamine-oxime (HMPAO) (Ceratec; Nycomed Amersham, Princeton, NJ, U.S.A.) was injected over a 30-second period to ensure that subjects were unaware of tracer administration. Subjects were scanned for 20 minutes using a PRISM 3000 gamma camera (Picker International, Cleveland, OH, U.S.A.). Data were normalized and co-registered, and subtraction images were compiled. Subtraction images contrasted activation patterns generated under the visual-only control condition to the auditory activation states acquired monaurally and binaurally. Results Right and left ear monaural stimulation in normal hearing subjects resulted in significant bilateral activation of Brodmann areas 41, 42, 21, 22, and 38. Although substantial intersubject response variability was noted, subjects generally failed to bilaterally activate these areas under monaural hearing aid presentations; however, bilateral activation of areas 41 and 22 was noted under binaural presentations. Conclusions Despite relatively similar hearing losses in each ear, significant differences in preoperative auditory corte- activation were observed between ears. These data suggest that functional brain imaging provides a useful tool for e-ploring the responsiveness of the auditory corte- in cochlear implant candidates. [source] RECTANGULARIZATION AND THE RISE IN LIMIT-LONGEVITY IN A SIMPLE OVERLAPPING GENERATIONS MODEL*THE MANCHESTER SCHOOL, Issue 1 2009GREGORY PONTHIERE Whereas overlapping generations (OLG) models with endogenous longevity do not distinguish between the rectangularization phenomenon and the rise in limit-longevity, these constitute two different demographic phenomena requiring a distinct modelling. This paper presents a two-period OLG model where the probability of survival from the first to the second period, as well as the maximum length of life, are endogenously determined and influenced by public policies. The issues of existence, uniqueness and stability of a steady state are studied. It is shown that the transition towards the steady state exhibits, under mild conditions, the observed succession of phases of rectangularization and derectangularization of survival curves. [source] Origins of the reversed flow over the windward Alpine foothills during MAP IOP3 and IOP8THE QUARTERLY JOURNAL OF THE ROYAL METEOROLOGICAL SOCIETY, Issue 615 2006N. Asencio Abstract The synoptic-scale situations during the two Intensive Observing Periods (IOPs) of the Mesoscale Alpine Programme (MAP) characterized by persisting precipitation and down-valley flow as observed by the Doppler on the wheel radar (DOW) over the two Alpine valleys (Toce and Ticino) were investigated. The first period (IOP3, 24,27 September 1999) was characterized by a south-westerly flow and convective precipitation, whereas the second period (IOP8, 20,21 October 1999) by a down-valley flow and stratiform precipitation. During IOP3, the down-valley northerly flow over the north-western part of the Po valley was confined within a thin layer of 200,300 m depth. During IOP8, the northerly flow extended from the Alps foothills to the Ligurian sea in a deep layer of 1,2 km height. The Meso-NH numerical model with a 2.5 km horizontal mesh grid reproduced the characteristics of both cases from the valley scale to the meso-, scale. Sensitivity experiments were, furthermore, performed in order to highlight the relationships between wet or dry drainage flow channelled by the Alpine orography, mesoscale upstream flow blocked by the Alps, and a regional cold pool at the foothills inside the Po valley. During IOP8, the diabatic processes were dominant at local scales in confirmation of Steiner results based on the DOW observations and they were significant at regional scales upstream of the Alps by maintaining a cold pool over the Po valley. The IOP3 low-level flow reversal occurred as the flow began to cross over the Alps instead of turning around. A downslope flow is associated with the blocked-regime period upstream of the Alps. Copyright © 2006 Royal Meteorological Society [source] Dynamics of extinction of a small population of the three-spined stickleback (Gasterosteus aculeatus L) caused by habitat modificationAQUATIC CONSERVATION: MARINE AND FRESHWATER ECOSYSTEMS, Issue 4 2010R. J. Wootton Abstract 1.Abundance of a population of three-spined stickleback, Gasterosteus aculeatus L., in a small backwater of Afon Rheidol in mid-Wales (UK) was estimated annually each October from 1972 to 1999 by mark,recapture. 2.The population became extinct in 2000, because of land-use changes in 1995, which modified the drainage pattern through the backwater, causing the backwater to eventually dry up. 3.The final decline to extinction started from an estimated abundance of 1550 in 1998 and the abundance in 1999, the year before extinction, was 85. The smallest abundance from which the population showed an increase was 670. 4.Two years before extinction (1998), the population was characterized by an anomalously high proportion of small fish. 5.There was a significant power relationship between the years to extinction and population size, but if the data were analysed in two periods, 1972,1989 and 1990,1999, the relationship was only significant for the second period. 6.There was no relationship between time to extinction and per capita annual rate of increase (k), although values of k were unusually low in the last two years before extinction. 7.Time to extinction was not related to mean length, mean mass or the condition of the fish. 8.The results suggest that the indicators of impending extinction may vary with the causes of extinction and may be ambiguous, even when a long time-series of demographic data is available. Copyright © 2010 John Wiley & Sons, Ltd. [source] Suboptimal thermoregulation in male adders (Vipera berus) after hibernation imposed by spermiogenesisBIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY, Issue 1 2007GÁBOR HERCZEG In ectotherms, the main behavioural option for thermoregulation is the adjustment of daily and seasonal activity to the thermal quality of the environment. While active, ectotherms thermoregulate by shuttling in between thermally differing microhabitat patches. Here, we focused on the question of whether other behavioural or physiological processes could force ectotherms to maintain activity during thermally unfavourable periods, when accurate thermoregulation is impossible. Using laboratory experiments and field data we compared the thermoregulation of male adders (Vipera berus) between two periods in spring when (1) only males and (2) also females and juveniles had terminated their winter hibernation. We found that males thermoregulated actively both in the lab and in the field. Accurate thermoregulation was only possible during the second period because of the low thermal quality of the environment. Male adders maintained a lower mean body temperature in the field than in the laboratory within both periods, and in addition their body temperature during the first period was on average 4 °C lower than during the second period. The thermal qualities of the natural basking sites showed a similar pattern. We discuss the results in the context of a potential trade-off between spermiogenesis and thermoregulation, where the benefits of early spermiogenesis coupled with inaccurate thermoregulation are higher than the associated costs. The results support the contention that the earlier spring emergence of the male compared with female adders is explainable by natural selection favouring early initiation of spermiogenesis, and hence sex differences in phenology. © 2007 The Linnean Society of London, Biological Journal of the Linnean Society, 2007, 92, 19,27. [source] Congenital malformations in infants born after in vitro fertilization in SwedenBIRTH DEFECTS RESEARCH, Issue 3 2010Bengt Källén Abstract BACKGROUND: The risk for congenital malformations is increased in infants born after in vitro fertilization (IVF). Some specific malformations appear to be more affected than others. METHODS: The presence of congenital malformations in 15,570 infants born after IVF with an embryo transfer between April 1, 2001, and the end of 2006 were compared with all infants born in Sweden during 2001 to 2007 (n = 689,157). Risk estimates were made after adjusting for year of birth, maternal age, parity, smoking, and body mass index. The risks of specific malformations were compared with data from a previous study (1982 to March 31, 2001) of 16,280 infants born after IVF. Different IVF methods were compared to respect to malformation risk. RESULTS: Increased risks of a similar magnitude were found for most cardiovascular malformations and limb reduction defects for both study periods. For neural tube defects, cardiac septal defects, and esophageal atresia, there was still an increased risk, but it was lower during the second than during the first period. For small bowel atresia, anal atresia, and hypospadias, the risk increase observed during the first study period had disappeared during the second period. An increased risk was seen for some syndromes that have been associated with imprinting errors. No difference in malformation risk according to IVF method was apparent. CONCLUSIONS: A slightly increased risk for congenital malformations after IVF persists. A decreasing risk is seen for some specific malformations, either true or the result of multiple testing. Birth Defects Research (Part A), 2010. © 2010 Wiley-Liss, Inc. [source] Strategic Choice of Quantity Stickiness and Stackelberg LeadershipBULLETIN OF ECONOMIC RESEARCH, Issue 1 2001Midori Hirokawa This paper re-examines endogenous Stackelberg leader,follower relations by modelling an explicitly dynamic market. We analyze a twice-repeated duopoly where, in the beginning, each firm chooses either a quantity-sticky production mode or a quantity-flexible production mode. The size of the market becomes observable after the first period. In the second period, a firm can adjust its quantity if and only if it has adopted the flexible mode. Hence, if one firm chooses the sticky mode whilst the other chooses the flexible mode, then they respectively play the roles of a Stackelberg leader and a Stackelberg follower in the second marketing period. Somewhat intriguing is the finding that such a Stackelberg-like equilibrium can arise only when the relative weight of the pre-Stackelberg first marketing period is sufficiently high, with time preferences being sufficiently strong. [source] Exposure of extremely low birth weight infants to diagnostic X-Rays: a longitudinal studyACTA PAEDIATRICA, Issue 2 2009Ilan Arad Abstract Aim: To quantify the number of chest and abdominal radiograms performed in surviving singleton extremely low birth weight (ELBW) infants in order to examine whether changes in imaging application occurred during the last 21 years (1987,2007). Methods: Clinical and radiological data of 225 out of 229 surviving infants were obtained and associations with time and clinical variables were evaluated. Results: The number of chest X-Rays performed per infant was 10.3 ± 11.1 (mean ± SD), median = 7; range = 0,77 and the number of abdominal radiograms was 5.6 ± 7.1, median = 3; range = 0,61. The number of chest and abdominal X-Rays performed per patient during 1987,1996 was very similar to that of 1997,2007, and no appreciable change of trend was observed along the years. There were negative and statistically significant correlations between the gestational age and the number of radiograms performed per patient (chest X-Rays: r =,0.402; p < 0.001, abdominal X-Rays: r =,0.182; p = 0.006). Controlling for gestational age, reduced numbers of radiograms per patient (abdominal: b =,1.20, p = 0.235; chest: b =,3.08, p = 0.035) were demonstrated in the second period. Patients with complicated clinical course were exposed to significantly more radiograms. Conclusion: Controlling for gestational age, a reduced number of exposures to chest radiograms was demonstrated during 1997,2007 compared with 1987,1996. Measures to reduce radiation, especially in complicated cases, are advocated. [source] Oesophageal resection for high-grade dysplasia in Barrett's oesophagusBRITISH JOURNAL OF SURGERY (NOW INCLUDES EUROPEAN JOURNAL OF SURGERY), Issue 8 2000Dr G. Zaninotto Background The aims of this study were to evaluate the prevalence of invasive cancer in patients with high-grade dysplasia in Barrett's oesophagus and to verify whether a second endoscopy with multiple biopsies could improve the accuracy of preoperative diagnosis. In addition, the mortality, morbidity and survival rates in patients with high-grade dysplasia having oesophageal resection were recorded. Methods Fifteen patients were observed from 1982 to 1998; the first seven patients were offered primary oesophageal resection after diagnosis. The other eight patients underwent a second endoscopy with a median of 12 biopsies examined. All later underwent oesophageal resection. Results Invasive adenocarcinoma was found in five patients, with a minimal difference between the first and second periods (two of seven versus three of eight). There were no perioperative deaths. Early morbidity was observed in eight patients and late morbidity in four. The actuarial survival rate was 79 per cent at 5 years. The Karnofsky status was unchanged from preoperative values in 13 of 15 patients after a median follow-up of 46 months. Conclusion These patients with high-grade dysplasia had a 33 per cent probability of harbouring invasive oesophageal carcinoma but even a second endoscopy failed to identify patients with invasive tumour. Oesophagectomy was performed with no deaths and remains a rational treatment in patients fit for surgery. © 2000 British Journal of Surgery Society Ltd [source] | ||||||||||||||||||||||||||||