Multiple Contracts Research Articles

Lymph Flow, Shear Stress, and Lymphocyte Velocity in Rat Mesenteric Prenodal Lymphatics

To measure lymphocyte velocity, lymphatic contraction, and shear stress in phasically contracting lymphatics in situ. A high-speed video system was used to capture multiple contraction cycles in rat mesenteric lymphatic preparations. The images were analyzed to determine fluid velocity, volume flow rate, wall shear stress, and retrograde flow. Lymphocyte density and flux varied from 326 to 35,500 cells/microL and 206 to 2,030 cells/min, respectively. Lymphatics contracted phasically, with a mean diameter 91 +/- 9.0 microm and amplitudes of 39%. Lymph velocity varied with the phasic contractions in both direction and magnitude with an average of 0.87 +/- 0.18 and peaks of 2.2-9.0 mm/s. The velocity was approximately 180 degrees out of phase with the contraction cycle. The average lymph flow was 13.95 +/- 5.27 microL/h with transient periods of flow reversal. This resulted in an average shear of 0.64 +/- 0.14 with peaks of 4-12 dynes/cm(2). High-speed lymphocyte tracking provided the spatial and temporal resolution to measure lymphocyte flux throughout the phasic contraction. Poiseuille flow was a reasonable model for estimating wall shear stress through most of the phasic contraction cycle of the intervalvular lymphatic segments. Shear rate was low but had large variations in magnitude compared to that seen in blood vessels.

Pricing and Hedging of Multi Type Contracts Under Multidimensional Risks in Incomplete Markets Modeled By General Itô Sde Systems

The HARA and CARA theory of pricing, and the theory of partial, yet the most conservative hedging, of a single (liquid) tradable derivative contract under multidimensionality of risks in incomplete markets, including markets with non-hedgable interest rate risks, was developed by the author in a recent paper. In the present paper this theory is extended to the general case of simultaneous pricing and hedging of multiple (types of) such contracts. The results are based on the generalization of the fundamental matrix of derivatives pricing and hedging to include multiple contracts. Some applications are discussed as well.

Time course of vasodilation at the onset of repetitive skeletal muscle contractions

To characterize the vasodilatory response in the transition from a single skeletal contraction to a series of contractions, we measured the response of hamster cremaster muscle arterioles associated with four to five skeletal muscle fibers stimulated to contract for one, two, three, or four contractions (250-ms train duration) at 4-s intervals [15 contractions per minute (CPM)] for up to 12 s, at stimulus frequencies of 4, 10, 20, 30, 40, 60, and 80 Hz. To investigate the contribution of contraction frequency, we stimulated muscle fiber bundles at 30 or 60 CPM for 12 s at stimulus frequencies of 4, 20, and 60 Hz. Arteriolar diameters at the site of overlap with the stimulated muscle fibers were measured before and after each contraction. At 15 CPM at 4, 20, and 60 Hz, we observed a peak change in diameter following the first contraction of 1.1 +/- 0.1, 1.6 +/- 0.2, and 2.1 +/- 0.2 mum that almost doubled in response to the second contraction (2.0 +/- 0.1, 3.0 +/- 0.1, and 3.8 +/- 0.1 mum, respectively), but there was no further dilation following the third or fourth contraction. A similar response occurred at all stimulus and contraction frequencies tested. At 30 and 60 CPM at 60 Hz, the plateau after two contractions was followed by a further increase in diameter to a second plateau at 7-8 s. Therefore, the vasodilatory response in the transition from single to multiple contractions had components that were stimulation parameter dependent and independent and showed a plateauing behavior indicative of rapid changes in either the nature and/or concentration of vasodilators released or changes in vascular reactivity.

Competitive Wages in a Match with Ordered Contracts

Following the recently dismissed antitrust lawsuit against the National Residency Matching Program (NRMP), Jeremy Bulow and Jonathan Levin (2006) propose a simple matching model in which firms set impersonal salaries simultaneously before matching with workers, which leads to lower aggregate wages than any competitive outcome. I model a feature of the NRMP, ordered contracts, that allows firms to set several contracts while determining the order in which they try to fill them, which has different properties than standard models with multiple contracts. Furthermore, the low wages of Bulow and Levin are no longer an equilibrium, but competitive wages are. (JEL D86, J31, J41)

Free or precarious? A comparison of the attitudes of workers in flexible and traditional employment contracts

This study contributes to research on the impact of different kinds of employment contract on worker attitudes in the context of debates about the changing nature of employment in the 21st century and in particular the emergence of what have been described as either free or precarious workers. Work experiences and attitudes associated with part-time, temporary and multiple contracts are compared with those of workers in single, permanent, full-time jobs. Among a sample of UK pharmacists, few significant differences are found between workers on any of these contracts, either singly or in combination, and those in traditional employment contracts. The role of contract of choice and work orientations as potential mediators was explored. Although both were associated with attitudes, they had only a very minor role as either mediators or moderators. It is concluded that among this sample of professional workers, those on atypical employment contracts report experiences and attitudes that are at least as positive as those of workers in traditional employment contracts.

Chloroplast DNA variation and geographical structure of the Aristolochia kaempferi group (Aristolochiaceae)

The present study documents cpDNA variation in the Aristolochia kaempferi group (Aristolochiaceae), which consists of one Chinese and all Japanese and Taiwanese species of the subgenus Siphisia. In a phylogenetic analysis based on the nucleotide sequences of the matK gene, and the atpB-rbcL and trnS-trnG intergenic spacer regions, 38 haplotypes were recognized in the A. kaempferi group and as many as 24 within A. kaempferi. This is the most haplotypes reported for a single species to date. Although six highly significant major clades were identified in the phylogenetic analysis, they were not congruent with previous classifications. This might be attributed to the specific speciation process, such as convergent evolution, incomplete lineage sorting, and/or reticulate evolution. The six major clades had a clear geographical distribution pattern and were significantly associated with geographical distribution of haplotypes in a nested clade analysis and AMOVA. The results allow us to deduce a scenario in which multiple contractions and expansions of the geographical ranges brought about by Quaternary climatic oscillations affected the patterns of genetic diversity. The present geographic patterns of haplotype distribution within the A. kaempferi group can be explained by the last postglacial range expansion from different refugia, and the boundaries may be suture zones.

Incentive maintenance outsourcing contracts for channel coordination and improvement

Consider a manufacturer who has a process with an increasing failure rate over time. In order to improve the process performance, the following two types of maintenance activity are outsourced to an external contractor: (i) preventive maintenance is performed periodically to improve the reliability of the process when the process is functional; and (ii) corrective maintenance is used to restore the process to a specified condition when it fails. We consider the use of incentive contracts to induce the contractor to select the maintenance policy that optimizes the total profit of the manufacturer and contractor. It is demonstrated that an incentive contract based on a combination of a target uptime level and a bonus always leads to the desired win-win coordination, and provides flexibility in allocating the extra profit generated from coordination and, importantly, an incentive to the contractor to improve the efficiency of the maintenance operations. The incentive contract can also be used to select the most economically efficient contractor from multiple contractors with different maintenance capabilities.

Maintenance outsourcing of a multi-process manufacturing system with multiple contractors

Consider a manufacturer with a manufacturing system that consists of multiple processes. The manufacturer's revenue is determined by the minimum of the uptimes among the processes. The maintenance functions of the processes are outsourced to independent contractors so that each contractor is responsible only for one process. A performance-based incentive contract is offered to each contractor, consisting of an uptime target level and a bonus rate for exceeding the uptime target. Under the incentive contract, a contractor receives a bonus only when the achieved uptime exceeds the target level specified in the contract. We develop a model for jointly determining the uptime target levels and bonus rates for the contractors which maximize system profit. We also demonstrate the financial benefits of coordination and added flexibility in allocating the additional profit to the contractors. In addition we show the impact of the variation in individual process maintenance times and costs on channel coordination and profits.

Uk Gas Markets: the Market Price of Risk and Applications to Multiple Interruptible Supply Contracts

We employ the Schwartz and Smith (2000) model to explore the dynamics of the UK gas markets. We discuss in detail the short-term and long-term market prices of risk borne by the market players and how deviations from expected cyclical storage affect the short-term market price of risk. Finally, we illustrate an application of the model by pricing interruptible supply contracts that are currently traded in the UK.

Postprandial transduodenal bolus transport is regulated by complex peristaltic sequence

To study the relationship between the patterns of postprandial peristalsis and transduodenal bolus transport in healthy subjects. Synchronous recording of chyme transport and peristaltic activity was performed during the fasting state and after administration of a test meal using a special catheter device with cascade configuration of impedance electrodes and solid-state pressure transducers. The catheter was placed into the duodenum, where the first channel was located in the first part of the duodenum and the last channel at the duodenojejunal junction. After identification of previously defined chyme transport patterns the associated peristaltic patterns were analyzed. The interdigestive phase 3 complex was reliably recorded with both techniques. Of 497 analyzed impedance bolus transport events, 110 (22%) were short-spanned propulsive, 307 (62%) long-spanned propulsive, 70 (14%) complex propulsive, and 10 (2%) retrograde transport. Short-spanned chyme transports were predominantly associated with stationary or propagated contractions propagated over short distance. Long-spanned and complex chyme transports were predominantly associated with propulsive peristaltic patterns, which were frequently complex and comprised multiple contractions. Propagated double wave contraction, propagated contraction with a clustered contraction, and propagated cluster of contractions have been identified to be an integralted part of a peristaltic sequence in human duodenum. Combined impedancometry and manometry improves the analysis of the peristaltic patterns that are associated with postprandial transduodenal chyme transport. Postprandial transduodenal bolus transport is regulated by propulsive peristaltic patterns, which are frequently complex but well organized. This finding should be taken into consideration in the analysis of intestinal motility studies.

Gestão dos múltiplos vínculos contratuais nas grandes empresas brasileiras

Este artigo analisa como os executivos das maiores empresas brasileiras estão lidando com a força de trabalho flexível, ao comparar a evolução do tratamento conferido aos trabalhadores do quadro efetivo das empresas com o tratamento conferido aos terceirizados. A pesquisa quantitativa realizada com 513 presidentes, diretores e altos executivos de 179 empresas sugere uma evolução das práticas de gestão de pessoas em geral e um aumento da distância no tratamento conferido aos terceirizados em relação aos empregados, em aspectos fundamentais da gestão de pessoas, como recompensa monetária por metas atingidas, comprometimento com os resultados, autonomia e compartilhamento do aprendizado. Também há evidências da tendência de ampliação da contratação de terceirizados. Conclui-se que as maiores empresas brasileiras se encontram ainda despreparadas para lidar com a complexidade advinda da proliferação da contratação de profissionais com múltiplos tipos de vínculos contratuais.

Effect of stretching on agonist–antagonist muscle activity and muscle force output during single and multiple joint isometric contractions

Eight moderately active male subjects where tested for peak force in an isometric knee extension test and peak force and rate of force development in an isometric squat test. Both tests where performed at a 100 degrees knee angle and average integrated electromyography (IEMG) was measured from the vastus medialis (VM), vastus lateralis (VL) and biceps femoris (BF) muscles. Subjects performed the two conditions, stretching (S) or control (C) in a randomized order. Subjects where tested for baseline strength measures in both the isometric knee extension and isometric squat and then either stretched or sat quietly for 10 min. Following S or C subjects where then tested at six time points. Following S peak force in the isometric knee extension was significantly (P < or = 0.05) less than C at 1, 2, 8 and 16 min post. No significant difference in peak force was found between S and C in the isometric squat. However, following S the rate of force development in the isometric squat was significantly less than C at immediately post. No significant differences where observed in IEMG of the VM or VL between S and C in either the isometric knee extension or isometric squat. However, IEMG significantly decreased in the BF at 1 min post after S in comparison with C in both the isometric knee extension and isometric squat. Stretching appears to decrease muscle force output in a single joint isometric contraction and rate of force development in a multiple joint isometric contraction. Possible changes in agonist-antagonist muscle activity patterns need to be further examined.

From “Endless Frontier” to “Basic Science for Use”: Social Contracts between Science and Society

This article analyzes the National Science Study produced by the Republican-dominated U.S. Congress in the mid-1990s to see if the priorities of S&amp;T policy were changing, if state agencies were being reorganized to achieve new priorities, and if universities were expected to work closely with industry in reconfigured agencies. Also analyzed was the economic composition of board members of eight S&amp;T policy organizations that informed the National Science Study. It was found that, generally, Republican policy supported both basic science and civilian technology policy but did not advocate reorganization of state administration of S&amp;T. However, a number of the S&amp;T policy groups pushed for the establishment of a separate mission agency for civilian technology. This suggests that conceptualization of a unitary social contract between science and society or iterated principal-agent relations expressing the interaction of science and society are insufficient because there may be multiple social contracts and many principals and agents.

Urodynamics-Based Evidence for the Beneficial Effect of Imipramine on Valve Bladders in Children

In an era, in which valve bladder is recognised as perhaps the single most important determinant of long-term outcome in patients with posterior urethral valves (PUV), an insight into the etiopathogenesis and management of valve bladders is warranted. The present study was designed to evaluate bladder dysfunction in PUV and to assess the response to imipramine in these patients, both subjectively and objectively, by serial urodynamic studies (UDS). From 1998-2001, 30 patients with PUV who had documented bladder dysfunction on UDS were studied. Patients with non-compliant or unstable bladders were treated with imipramine (1.5 - 2 mg/kg). All the patients in the present study were 5 years or older and hence old enough to be toilet trained. Assessment of continence and side effects of the drug was done after 3 months and repeat UDS were done at 3-6 months, 1 and 2 years. On the basis of initial treatment, the patients were divided into 2 groups; a fulguration group (n = 10, 33.3 %) and a vesicostomy group (n = 20, 66.6 %). Symptomatic voiding dysfunction was present in 27 of the 30 patients (90 %). Two patterns of urodynamic abnormalities were noted in the present study; 1) unstable bladders with single or multiple uninhibited contractions (18/30 patients, 60 %), and 2) small capacity, hypocompliant, hypertonic bladder (12/30 patients, 40 %). Post imipramine therapy significant symptomatic improvement was noted in 16/30 patients. On serial UDS, there was a 18-20 % increase in maximum cystometric capacity (MCC) and 30-35 % increase in pressure specific bladder volume (PSBV) following one year of imipramine therapy in 16/30 patients and 11/30 patients, respectively. 4 patients failed to show any improvement in MCC and PSBV with imipramine, they had been initially diverted with vesicostomy and later required augmentation cystoplasty. Unstable bladders and those with marginal bladder capacity and compliance showed the best response to imipramine therapy. Fibrotic, small capacity, hypertonic bladders are less responsive to imipramine. However, a trial of imipramine therapy is still warranted in these patients, as only 4/12 (33.3 %) patients with fibrotic hypertonic bladders failed to show any response and ultimately required augmentation cystoplasty. Imipramine qualifies as an effective and cheap drug for valve bladders.

Constrictive Pericarditis From a Severely Calcified Pericardium

A 42-year-old otherwise healthy woman presented with palpitations and gradual dyspnea on exertion. Her ECG showed normal sinus rhythm, an incomplete left bundle-branch block, and multiple premature atrial contractions. A posterior-anterior and lateral chest x-ray (Figure 1) demonstrated severe, dense calcification of the pericardium. The patient had been having palpitations for the past year and indolent dyspnea …

Prey Tracking by Larval Zebrafish: Axial Kinematics and Visual Control

High-speed imaging was used to record the prey-tracking behavior of larval zebrafish as they fed upon paramecium. Prey tracking is comprised of a variable set of discrete locomotor movements that together align the larva with the paramecium and bring it into close proximity, usually within one body length. These tracking behaviors are followed by a brief capture swim bout that was previously described [Borla et al., 2002]. Tracking movements were classified as either swimming or turning bouts. The swimming bouts were similar to a previously characterized larval slow swim [Budick and O’Malley, 2000], but the turning movements consisted of unique J-shaped bends which appear to minimize forward hydrodynamic disturbance when approaching the paramecium. Such J-turn tracking bouts consisted of multiple unilateral contractions to one side of the body. J-turns slowly and moderately alter the orientation of the larva – this is in contrast to previously described escape and routine turns. Tracking behaviors appear to be entirely visually guided. Infra-red (IR) imaging of locomotor behaviors in a dark environment revealed a complete absence of tracking behaviors, even though the normal repertoire of other locomotive behaviors was recorded. Concomitantly, such larvae were greatly impaired in consuming paramecia. The tracking behavior is of interest because it indicates the presence of sophisticated locomotor control circuitry in this relatively simple model organism. Such locomotor strategies may be conserved and elaborated upon by other larval and adult fishes.

Assessing the performance of construction projects: Implementing earned value management at the General Services Administration

There are many potential measures of performance for evaluating the success of a construction project. All address performance in three key areas: scope, schedule and budget. In a performance measurement framework where senior management wishes to minimise the numberof performance measures it employs, while ensuring maximal coverage or visibility into the programme, having a tool that captures each of the three areas would be ideal. Project managers have used Earned Value Management (EVM) for over 40 years to track actual schedule progress and actual costs against project plans. Earned Value Management has traditionally been applied to individual projects on which the manager is accountable for both schedule and cost variances. This paper proposes methods to apply EVM principles to allow: (1) analysis of portfolios of construction projects; (2) incorporation of the analysis into an innovative pay‐for‐performance human resources practice; and (3) use of regression analysis to develop baseline earned value curves. These extensions fit the needs of many government managers, who oversee a range of projects by multiple contractors, and whose cost risk is primarily due to schedule slips and change orders. Earned Value Management is described in the context of project oversight, and a dashboard system of performance measures is proposed for quickly assessing individual projects and portfolios. A method of generating standardised planned value curves is then specified, based on data from previous and ongoing projects. The paper concludes by showing how the US General Services Administration’s Public Buildings Service is using these methods to analyse and oversee its portfolio of new construction and major repair and alteration projects.

Predictable Dynamics in the S&amp;P 500 Index Options Implied Volatility Surface*

One key stylized fact in the empirical option pricing literature is the existence of an implied volatility surface (IVS). The usual approach consists of Þtting a linear model linking the implied volatility to the time to maturity and the moneyness, for each cross section of options data. However, recent empirical evidence suggests that the parameters characterizing the IVS change over time. In this paper we study whether the resulting predictability patterns in the IVS coefficients may be exploited in practice. We propose a two-stage approach to modeling and forecasting the S&P 500 index options IVS. In the Þrst stage we model the surface along the cross-sectional moneyness and time-to-maturity dimensions, similarly to Dumas et al. (1998). In the second-stage we model the dynamics of the cross-sectional Þrst-stage implied volatility surface coefficients by means of vector autoregression models. We Þnd that not only the S&P 500 implied volatility surface can be successfully modeled, but also that its movements over time are highly predictable in a statistical sense. We then examine the economic signiÞcance of this statistical predictability with mixed Þndings. Whereas proÞtable delta-hedged positions can be set up that exploit the dynamics captured by the model under moderate transaction costs and when trading rules are selective in terms of expected gains from the trades, most of this proÞtability disappears when we increase the level of transaction costs and trade multiple contracts off wide segments of the IVS. This suggests that predictability of the time-varying S&P 500 implied volatility surface may be not inconsistent with market efficiency.

Chronicle of the World: The Complete and Annotated Nuremberg Chronicle of 1493 by Hartmann s&gt; Schedel (review)

REVIEWS 749 Schedel, Hartmann. Chronicle oftheWorld:7he Complete andAnnotated Nuremberg Chronicle ofI493. Introductionand appendixby Stephan Fussel.Taschen, Cologne and London, 200I. 68o pp. Illustrations. Notes. Appendix. Bibliography.Index. ?4o.oo: E6o.oo. ADVERTISED in I493 as an object that promises 'greaterand deeper pleasure' than anything else to 'scholars and men of learning', the Chronicle by Hartmann Schedel was indeed a particularjewel of the humanistpublishing world. Planned in the tradition of late medieval chronicles and modelled on biblical chronology, Schedel's work does not fail to charm even today. It departs from previously used patterns by addressing humanist issues and themes, endeavouring some kind of 'total history' of the world, the church, classical antiquity, medieval and contemporary wars and events. It also includesstoriesaboutthe appearanceofmiraculoussigns,a historyof idolatry, a chronicle of rulers,philosophers, orators and men of science all across the 'six ages of the world', with a seventh attached, warning of the coming of the Antichrist and the Apocalypse. Most unusually, it comprises interspersed with the chronological narrative brief histories and colourful panoramas of famous cities from all over the world. Thus the aestheticvalue of the book is one of its most attractivefeatures,especiallyin this sumptuous, velvet-bound facsimileedition publishedby Taschen in 200 I, introducedand annotated in an appendix, both in English,by Stephan Fussel. Containing a biographical surveyof Schedel'slife and work as a physician and humanist, born among the patriciate of the city of Nuremberg in I440, the introduction provides a useful account of the intellectual and cultural contextwithinwhich thishumanistscholarandpatricianfunctioned.Contacts to other German humanists of his generation, as well as to the political and artisan elite of his native city, enabled Schedel to find the intellectual and material support he needed to promote his project. Ftusselgoes into some detail when he describes the actual production process of this monumental work, which involved multiple contracts between sponsors, printers, illustrators , booktraders and sales agents among the scholarly community and Schedel himself. Complicated negotiations must have occurred concerning the exact typeface, the paper quality, and the number of planned editions. Fuisselaccepts,for example, the previousspeculationby arthistoriansthatone of Nuremberg's most famous artists the painter Albrecht Durer contributed to the woodcuts in the book, though he does not confirm this thesiswith clear evidence. All of this indicates that Schedel's chronicle was projected as a successful enterprise of the late-fifteenth-century publishing world a planned 'bestseller',aimed at a relativelylarge literateand art-interestedpublic, much beyond Nuremberg's city walls. The distributionnetwork spanned Europewide . Three differenttypes of editions were planned in the firstinstance: an unbound, uncoloured (and therefore cheap) version, an uncoloured and bound copy, and a bound and coloured copy for a richer clientele. Around I400 copies were produced in Latin, the linguafranca of humanistEurope, and 700 copies in German. The lasting influence the chronicle had after its publication is not only reflectedin a great number of (unauthorized)reprints, 750 SEER, 82, 3, 2004 but also in the impact on culturalhistoryitself:the firstversion of the storyof Doctor Faustus, written in I587, depicts the fated doctor travelling across Europe along the itineraryoutlined by the sequence of Schedel'scities. The chroniclerwas not left to fend for himself,even duringthe compilation of the texts. As in most encyclopedias, several authors participated (visible from at least seven differenthandwritingsin the originalmanuscriptsources), as did several illustrators,who provided the woodcuts. Several apprentices had to travel around I,5oo kilometresto produce thirty-twowoodcuts which claim to depict authenticviews of European cities, although some city-scapes were taken from other contemporary illustrationsor imaginary panoramas. Limits on the travelbudget meant that no authenticviews could be provided of Spanish, English,Dutch or Flemishcities.The copy which servedas a basis for the present reprintis one of the 300 complete and best preservedcopies in German, held at the Herzogin Anna Amelia Libraryin Weimar. The appendix, also by Ftissel, provides a most useful guide through the various books and parts of the chronicle, explaining the compilers' Renaissance method of critical analysis: the origin of the world, for example, is discussed by Schedel by introducing the 'errors' of the Ancients, before contrasting them with the 'true account' of the Bible. Interesting is also Schedel's use of maps, which are stillbased on the Greek and...

Nonlinear price discrimination with a finite number of consumers and constrained recontracting

In the monopoly nonlinear pricing problem with unobservable consumer types, we study mechanisms in which the firm makes the set of consumer options conditional on the aggregate reports of consumer types it receives. Previous mechanisms that exploit knowledge of the true type distribution often have multiple equilibria or use noncredible contracts off the equilibrium path. When the monopolist can replace contracts after initial reports subject to the constraint that truthful consumers are not made worse off, the outcome is essentially the same as when the monopolist has full information. This holds whether or not the monopolist can make offers to consumers who reject all original contract offers. When the monopolist must guarantee nonnegative surplus to all truthful consumers in all contingencies, the equilibrium outcome has undistorted contracts but lower profits for the monopolist.