Transfer of MPEG-2 Transport Stream over MPLS

This study examines how MPEG-2 Transport Stream, used in DVB-T video transmission, can be reliably and efficiently transferred to remote locations over an MPLS network. All the relevant technologies used in this scenario are also discussed in the study. This study was done for Digita Oy, which is a major radio and television content distributor in Finland. The theoretical part of the study begins with the introduction to MPLS technology and continues with explanation of IP Multicast and its components. The fourth section discusses MPEG-2 and the formation and content of MPEG-2 Transport Stream. These technologies were studied in relevant literature and RFC documentation. After the theoretical part of the study, the test setup and the test cases are presented. The results of the test cases, and the conclusions that can be drawn based on them, are discussed in the last section of the study. The tests showed that it is possible to transfer digital video quite reliably over an MPLS network using IP Multicast. By configuring the equipment correctly, the recovery time of the network in case of a failure can be shortened remarkably. Also, the unwanted effect of other traffic on the critical video traffic can be eliminated by defining the Quality of Service parameters correctly. There are, however, some issues that need to be tested further before this setup can be used in broadcast networks. Reliable operation of IP Multicast and proper error correction are the main subjects for future testing.

Effect of hypoxia on cerebral blood flow regulation during rest and exercise : role of cerebral oxygen delivery on performance

Adequate supply of oxygen to the brain is critical for maintaining normal brain function. Severe hypoxia, such as that experienced during high altitude ascent, presents a unique challenge to brain oxygen (O2) supply. During high-intensity exercise, hyperventilation-induced hypocapnia leads to cerebral vasoconstriction, followed by reductions in cerebral blood flow (CBF), oxygen delivery (DO2), and tissue oxygenation. This reduced O2 supply to the brain could potentially account for the reduced performance typically observed during exercise in severe hypoxic conditions. The aims of this thesis were to document the effect of acute and chronic exposure to hypoxia on CBF control, and to determine the role of cerebral DO2 and tissue oxygenation in limiting performance during exercise in severe hypoxia. We assessed CBF, arterial O2 content (CaO2), haemoglobin concentration ([Hb]), partial pressure of arterial O2 (PaO2), cerebrovascular CO2 reactivity, ventilatory response to CO2, cerebral autoregulation (CA), and estimated cerebral DO2 (CBF ⨉ CaO2) at sea level (SL), upon ascent to 5,260 m (ALT1), and following 16 days of acclimatisation to 5,260 m (ALT16). We found an increase in CBF despite an elevated cerebrovascular CO2 reactivity at ALT1, which coincided with a reduced CA. Meanwhile, PaO2 was greatly decreased despite increased ventilatory drive at ALT1, resulting in a concomitant decrease in CaO2. At ALT16, CBF decreased towards SL values, while cerebrovascular CO2 reactivity and ventilatory drive were further elevated. Acclimatisation increased PaO2, [Hb], and therefore CaO2 at ALT16, but these changes did not improve CA compared to ALT1. No differences were observed in cerebral DO2 across SL, ALT1, and ALT16. Our findings demonstrate that cerebral DO2 is maintained during both acute and chronic exposure to 5,260 m, due to the reciprocal changes in CBF and CaO2. We measured middle cerebral artery velocity (MCAv: index of CBF), cerebral DO2, ventilation (VE), and performance during incremental cycling to exhaustion and 15km time trial cycling in both normoxia and severe hypoxia (11% O2, normobaric), with and without added CO2 to the inspirate (CO2 breathing). We found MCAv was higher during exercise in severe hypoxia compared in normoxia, while cerebral tissue oxygenation and DO2 were reduced. CO2 breathing was effective in preventing the development of hyperventilation-induced hypocapnia during intense exercise in both normoxia and hypoxia. As a result, we were able to increase both MCAv and cerebral DO2 during exercise in hypoxia with our CO2 breathing setup. However, we concomitantly increased VE and PaO2 (and presumably respiratory work) due to the increased hypercapnic stimuli with CO2 breathing, which subsequently contributed to the cerebral DO2 increase during hypoxic exercise. While we effectively restored cerebral DO2 during exercise in hypoxia to normoxic values with CO2 breathing, we did not observe any improvement in cerebral tissue oxygenation or exercise performance. Accordingly, our findings do not support the role of reduced cerebral DO2 in limiting exercise performance in severe hypoxia. -- Un apport adéquat en oxygène au niveau du cerveau est primordial pour le maintien des fonctions cérébrales normales. L'hypoxie sévère, telle qu'expérimentée au cours d'ascensions en haute altitude, présente un défi unique pour l'apport cérébral en oxygène (O2). Lors d'exercices à haute intensité, l'hypocapnie induite par l'hyperventilation entraîne une vasoconstriction cérébrale suivie par une réduction du flux sanguin cérébral (CBF), de l'apport en oxygène (DO2), ainsi que de l'oxygénation tissulaire. Cette réduction de l'apport en O2 au cerveau pourrait potentiellement être responsable de la diminution de performance observée au cours d'exercices en condition d'hypoxie sévère. Les buts de cette thèse étaient de documenter l'effet de l'exposition aiguë et chronique à l'hypoxie sur le contrôle du CBF, ainsi que de déterminer le rôle du DO2 cérébral et de l'oxygénation tissulaire comme facteurs limitant la performance lors d'exercices en hypoxie sévère. Nous avons mesuré CBF, le contenu artériel en oxygène (CaO2), la concentration en hémoglobine ([Hb]), la pression partielle artérielle en O2 (PaO2), la réactivité cérébrovasculaire au CO2, la réponse ventilatoire au CO2, et l'autorégulation cérébrale sanguine (CA), et estimé DO2 cérébral (CBF x CaO2), au niveau de la mer (SL), au premier jour à 5.260 m (ALT1) et après seize jours d'acclimatation à 5.260 m (ALT16). Nous avons trouvé des augmentations du CBF et de la réactivité cérébrovasculaire au CO2 après une ascension à 5.260 m. Ces augmentations coïncidaient avec une réduction de l'autorégulation cérébrale. Simultanément, la PaO2 était grandement réduite, malgré l'augmentation de la ventilation (VE), résultant en une diminution de la CaO2. Après seize jours d'acclimatation à 5.260 m, le CBF revenait autour des valeurs observées au niveau de la mer, alors que la réactivité cérébrovasculaire au CO2 et la VE augmentaient par rapport à ALT1. L'acclimatation augmentait la PaO2, la concentration en hémoglobine, et donc la CaO2, mais n'améliorait pas l'autorégulation cérébrale, comparé à ALT1. Aucune différence n'était observée au niveau du DO2 cérébral entre SL, ALT1 et ALT16. Nos résultats montrent que le DO2 cérébral est maintenu constant lors d'expositions aiguë et chronique à 5.260m, ce qui s'explique par la réciprocité des variations du CBF et de la CaO2. Nous avons mesuré la vitesse d'écoulement du sang dans l'artère cérébrale moyenne (MCAv : un indice du CBF), le DO2 cérébral, la VE et la performance lors d'exercice incrémentaux jusqu'à épuisement sur cycloergomètre, ainsi que des contre-la-montres de 15 km en normoxie et en hypoxie sévère (11% O2, normobarique) ; avec ajout ou non de CO2 dans le mélange gazeux inspiré. Nous avons trouvé que MCAv était plus haute pendant l'exercice hypoxique, comparé à la normoxie alors que le DO2 cérébral était réduit. L'ajout de CO2 dans le gaz inspiré était efficace pour prévenir l'hypocapnie induite par l'hyperventilation, qui se développe à l'exercice intense, à la fois en normoxie et en hypoxie. Nous avons pu augmenter MCAv et le DO2 cérébral pendant l'exercice hypoxique, grâce à l'ajout de CO2. Cependant, nous avons augmenté la VE et la PaO2 (et probablement le travail respiratoire) à cause de l'augmentation du stimulus hypercapnique. Alors que nous avons, grâce à l'ajout de CO2, efficacement restauré le DO2 cérébral au cours de l'exercice en hypoxie à des valeurs obtenues en normoxie, nous n'avons observé aucune amélioration dans l'oxygénation du tissu cérébral ou de la performance. En conséquence, nos résultats ne soutiennent pas le rôle d'un DO2 cérébral réduit comme facteur limitant de la performance en hypoxie sévère.

The automatic selection of ventilation parameters during the initial phase of mechanical ventilation.

OBJECTIVE: To test a method that allows automatic set-up of the ventilator controls at the onset of ventilation. DESIGN: Prospective randomized crossover study. SETTING: ICUs in one adult and one children's hospital in Switzerland. PATIENTS: Thirty intubated stable, critically ill patients (20 adults and 10 children). INTERVENTIONS: The patients were ventilated during two 20-min periods using a modified Hamilton AMADEUS ventilator. During the control period the ventilator settings were chosen immediately prior to the study. During the other period individual settings were automatically determined by the ventilatior (AutoInit). MEASUREMENTS AND RESULTS: Pressure, flow, and instantaneous CO2 concentration were measured at the airway opening. From these measurements, series dead space (V(DS)), expiratory time constant (RC), tidal volume (VT, total respiratory frequency (f(tot), minute ventilation (MV), and maximal and mean airway pressure (Paw, max and Paw, mean) were calculated. Arterial blood gases were analyzed at the end of each period. Paw, max was significantly less with the AutoInit ventilator settings while f(tot) was significantly greater (P < 0.05). The other values were not statistically significant. CONCLUSIONS: The AutoInit ventilator settings, which were automatically derived, were acceptable for all patients for a period of 20 min and were not found to be inferior to the control ventilator settings. This makes the AutoInit method potentially useful as an automatic start-up procedure for mechanical ventilation.

Dietary supplementation with omega-3 in cystic fibrosis patients

Accumulation of neutr ophils releasing proteolytic enzymes and free radicals induceprogressive lung tissue destruction in CF. Among several hfflammatory mediatorsimplicated in this process, leukotriene B 4 (LTB4) product of arachidonic (AA;20:4n 6) omega 6 polytmsaturated fatty acid (PUFA) plays an important role.Various anti inflammatory strategies including dietary supplementation of omega 3PUFA, known to favor the synthesis of less active leukotriene B 5 (LTBs), have beeninvestigated. To further explore this nutritional approach, biological effects of anomega 3 PUFA oral supplementation (n 3 OS) were measured in 17 CF patients haa prospective, randomized, double blind, crossover study. CF patients (mean age:18 + 9 years, FEVI: 66 + 29 %) received a dietary supplementation enriched, or not,ha omega 3 PUFA during a 2 x 6 months period. A modification in neutrophilmembrane PUFA composition was observed under n 3 OS with an increase in EPA(20:5n 3) PUFA (from 0.66 ± 0.56 to 1.60 ± 0.61 ~tmol %, P< 0.01). The LTB jLTB 5ratio was decreased (from 72 + 27 to 24 + 7, P< 0.C~31), in CF patients taking n 3OS. However, n 3 OS supplementation did neither affect the internalization of bothIL 8 receptors following IL 8 exposure, nor IL 8 induced neutrophil chemotaxis.Our results show that n 3 PUFA are absorbed and incorporated in neutrophilmembrmae. The consecutive decrease ha LTBjLTB 5 ratio suggests that, ha theseconditions, neutr ophils may produce less toxic mediators from the AA pathway. Thepotential clinical benefit for CF patients still needs to be assessed with furtherstudies of longer duration and including more patients.

A neuropsychological instrument measuring age-related cerebral decline in older drivers: development, reliability, and validity of MedDrive.

When facing age-related cerebral decline, older adults are unequally affected by cognitive impairment without us knowing why. To explore underlying mechanisms and find possible solutions to maintain life-space mobility, there is a need for a standardized behavioral test that relates to behaviors in natural environments. The aim of the project described in this paper was therefore to provide a free, reliable, transparent, computer-based instrument capable of detecting age-related changes on visual processing and cortical functions for the purposes of research into human behavior in computational transportation science. After obtaining content validity, exploring psychometric properties of the developed tasks, we derived (Study 1) the scoring method for measuring cerebral decline on 106 older drivers aged ≥70 years attending a driving refresher course organized by the Swiss Automobile Association to test the instrument's validity against on-road driving performance (106 older drivers). We then validated the derived method on a new sample of 182 drivers (Study 2). We then measured the instrument's reliability having 17 healthy, young volunteers repeat all tests included in the instrument five times (Study 3) and explored the instrument's psychophysical underlying functions on 47 older drivers (Study 4). Finally, we tested the instrument's responsiveness to alcohol and effects on performance on a driving simulator in a randomized, double-blinded, placebo, crossover, dose-response, validation trial including 20 healthy, young volunteers (Study 5). The developed instrument revealed good psychometric properties related to processing speed. It was reliable (ICC = 0.853) and showed reasonable association to driving performance (R (2) = 0.053), and responded to blood alcohol concentrations of 0.5 g/L (p = 0.008). Our results suggest that MedDrive is capable of detecting age-related changes that affect processing speed. These changes nevertheless do not necessarily affect driving behavior.

Vacuum assisted venous drainage does not increase trauma to blood cells.

Although gravity drainage has been the standard technique for cardiopulmonary bypass (CPB), the development of min imally invasive techniques for cardiac surgery has renewed interest in using vacuum assisted venous drainage (VAVD) Dideco (Mirandola, Italy) has modified the D903 Avant oxygenator to apply a vacuum to its venous reservoir. The impact of VAVD on blood damage with this device is analyzed. Six calves (mean body weight, 71.3 +/- 4.1 kg) were con nected to CPB by jugular venous and carotid arterial cannu lation, with a flow rate of 4-4.51 L/min for 6 h. They were assigned to gravity drainage (standard D903 Avant oxygen ator, n = 3) or VAVD (modified D903 Avant oxygenator, n = 3). The animals were allowed to survive for 7 days. A standard battery of blood samples was taken before bypass, throughout bypass, and 24 h, 48 h, and 7 days after bypass. Analysis of variance was used for repeated measurements. Thrombocyte and white blood cell counts, corrected by hematocrit and normalized by prebypass values, were not significantly different between groups throughout all study periods. The same holds true for hemolytic parameters (lactate dehydrogenase [LDH] and plasma hemoglobin). Both peaked at 24 hr in the standard and VAVD groups: LDH, 2,845 +/- 974 IU/L vs. 2,537 +/- 476 IU/L (p = 0.65), respectively; and plasma hemoglobin, 115 +/- 31 mg/L vs. 89 +/- 455 mg/L (p = 0.45), respectively. In this experimental setup with prolonged perfusion time, VAVD does not increase trauma to blood cells in comparison with standard gravity drainage.

High-resolution 3D whole-heart coronary MRA: a study on the combination of data acquisition in multiple breath-holds and 1D residual respiratory motion compensation.

OBJECT: To study a scan protocol for coronary magnetic resonance angiography based on multiple breath-holds featuring 1D motion compensation and to compare the resulting image quality to a navigator-gated free-breathing acquisition. Image reconstruction was performed using L1 regularized iterative SENSE. MATERIALS AND METHODS: The effects of respiratory motion on the Cartesian sampling scheme were minimized by performing data acquisition in multiple breath-holds. During the scan, repetitive readouts through a k-space center were used to detect and correct the respiratory displacement of the heart by exploiting the self-navigation principle in image reconstruction. In vivo experiments were performed in nine healthy volunteers and the resulting image quality was compared to a navigator-gated reference in terms of vessel length and sharpness. RESULTS: Acquisition in breath-hold is an effective method to reduce the scan time by more than 30 % compared to the navigator-gated reference. Although an equivalent mean image quality with respect to the reference was achieved with the proposed method, the 1D motion compensation did not work equally well in all cases. CONCLUSION: In general, the image quality scaled with the robustness of the motion compensation. Nevertheless, the featured setup provides a positive basis for future extension with more advanced motion compensation methods.

Globalization and risk sharing

We study the effects of globalization on risk sharing and welfare. Like previous literature, weassume that countries cannot commit to repay their debts. Unlike previous literature, we assumethat countries cannot discriminate between domestic and foreign creditors when repaying theirdebts. This creates novel interactions between domestic and international trade in assets. (i)Increases in domestic trade raise the bene.ts of enforcement and facilitate international trade.In fact, in our setup countries can obtain international risk sharing even in the absence of defaultpenalties. (ii) Increases in foreign trade .i.e. globalization.raise the costs of enforcement andhamper domestic trade. As a result, globalization may worsen domestic risk sharing and lowerwelfare. We show how these e¤ects depend on various characteristics of tradable goods andexplore the roles of borrowing limits, debt renegotiations, and trade policy.

Standardized enforcement: Access to justice vs contractual innovation

We model the different ways in which precedents and contract standardization shapethe development of markets and the law. In a setup where more resourceful parties candistort contract enforcement to their advantage, we find that the introduction of astandard contract reduces enforcement distortions relative to precedents, exerting twoeffects: i) it statically expands the volume of trade, but ii) it crowds out the use ofinnovative contracts, hindering contractual innovation. We shed light on the largescale commercial codification occurred in the 19th century in many countries (evenCommon Law ones) during a period of booming commerce and long distance trade.

Solving two production scheduling problems with sequence-dependent set-up times

In today’s competitive markets, the importance of goodscheduling strategies in manufacturing companies lead to theneed of developing efficient methods to solve complexscheduling problems.In this paper, we studied two production scheduling problemswith sequence-dependent setups times. The setup times areone of the most common complications in scheduling problems,and are usually associated with cleaning operations andchanging tools and shapes in machines.The first problem considered is a single-machine schedulingwith release dates, sequence-dependent setup times anddelivery times. The performance measure is the maximumlateness.The second problem is a job-shop scheduling problem withsequence-dependent setup times where the objective is tominimize the makespan.We present several priority dispatching rules for bothproblems, followed by a study of their performance. Finally,conclusions and directions of future research are presented.

International consumption risk sharing

This paper formally examines the implications of international consumptionrisk sharing for a panel of industrialized countries. We theoretically derivethe international consumption insurance proposition in a simple setup and showhow it should be modified in more complicated models. We empirically analyzethe implications of the theory for pairs of countries across frequencies of thespectrum and find that aggregate domestic consumption is almost completelyinsured against idiosyncratic real, demographic, fiscal and monetary shocksover short cycles, but that it covaries with these variables over medium andlong cycles. The cross equation restrictions imposed by the theory are, ingeneral, rejected. The policy implications of the results are discussed.

Intraspecific competition reveals conditional fitness effects of single gene polymorphism at the Arabidopsis root growth regulator BRX.

Intraspecific genetic variation for morphological traits is observed in many organisms. In Arabidopsis thaliana, alleles responsible for intraspecific morphological variation are increasingly being identified. However, the fitness consequences remain unclear in most cases. Here, the fitness effects of alleles of the BRX gene are investigated. A brx loss-of-function allele, which was found in a natural accession, results in a highly branched but poorly elongated root system. Comparison between the control accession Sav-0 and an introgression of brx into this background (brxS) indicated that, surprisingly, brx loss of function did not negatively affect fitness in pure stands. However, in mixed, well-watered stands brxS performance and reproductive output decreased significantly, as the proportion of Sav-0 neighbors increased. Additional comparisons between brxS and a brxS line that was complemented by a BRX transgene confirmed a direct effect of the loss-of-function allele on plant performance, as indicated by restored competitive ability of the transgenic genotype. Further, because plant height was very similar across genotypes and because the experimental setup largely excluded shading effects, the impaired competitiveness of the brx loss-of-function genotype likely reflects below-ground competition. In summary, these data reveal conditional fitness effects of a single gene polymorphism in response to intraspecific competition in Arabidopsis.

The equity premium and the risk free rate: A cross country, cross maturity examination

This paper examines the relationship between the equity premium and the risk free rate at three different maturities using post 1973 data fora panel of 7 OECD countries. We show the existence of subsample instabilities,of some cross country differences and of inconsistencies with the expectations theory of the term structure. We perform simulations using a standard consumptionbased CAPM model and demonstrate that the basic features of Mehra and Prescott's(1985) puzzle remain, regardless of the time period, the investment maturity and the country considered. Modifications of the basic setup are also considered.

Speed of convergence of recursive least squares learning with ARMA perceptions

This paper fills a gap in the existing literature on least squareslearning in linear rational expectations models by studying a setup inwhich agents learn by fitting ARMA models to a subset of the statevariables. This is a natural specification in models with privateinformation because in the presence of hidden state variables, agentshave an incentive to condition forecasts on the infinite past recordsof observables. We study a particular setting in which it sufficesfor agents to fit a first order ARMA process, which preserves thetractability of a finite dimensional parameterization, while permittingconditioning on the infinite past record. We describe how previousresults (Marcet and Sargent [1989a, 1989b] can be adapted to handlethe convergence of estimators of an ARMA process in our self--referentialenvironment. We also study ``rates'' of convergence analytically and viacomputer simulation.

Choice of partners in multiple two-person prisoner's dilemma games: An experimental study

We examine the effect of unilateral and mutual partner selection in the context of prisoner's dilemmas experimentally. Subjects play simultaneously several finitely repeated two-person prisoner's dilemma games. We find that unilateral choice is the best system. It leads to low defection and fewer singles than with mutual choice. Furthermore, with the unilateral choice setup we are able to show that intendingdefectors are more likely to try to avoid a match than intending cooperators. We compare our results of multiple games with single game PD-experiments and find no difference in aggregate behavior. Hence the multiple game technique is robust and might therefore be an important tool in the future for testing the use of mixed strategies.