Seasonal Stability Tests in gretl. An Application to International Tourism Data

The seasonal stability tests of Canova & Hansen (1995) (CH) provide a method complementary to that of Hylleberg et al. (1990) for testing for seasonal unit roots. But the distribution of the CH tests are unknown in small samples. We present a method to numerically compute critical values and P-values for the CH tests for any sample size and any seasonal periodicity. In fact this method is applicable to the types of seasonality which are commonly in use, but also to any other.

Selektionsuntersuchungen an Schleppnetzsteerten für den Plattfischfang in der Ostsee

The intensified trawl fishery for flounder and otherflatfishes along the German Baltic coast during summer months resulted in the problem of increased undersized bycatches and their discarding. Thereforeselectivity trials with a standard codend, a codend withenlarged meshes and a so-called multipanel codendwith partly transverse netting were investigated. Results show that improvements in selectivity are possible, and tests including UW-TV observations shouldbe continued.

Bearbeitung von Fangproben mit neuen elektronischen Messmethoden

For 10 years the Institute for Fishing Technology, Hamburg (IFH) has been carrying out experiments in the brown shrimp fishery with beam trawls aiming at a reduction of unwanted bycatches. When the tests were transferred to commercial fishery conditions the personnel effort and costs increased markedly. It became e.g. necessary to install a deep-freeze chain to make it possible to evaluate more samples in the laboratory. This again required to increase the number of technicians for measuring the fish and shrimp samples, but also made it necessary to perform this work in the most rational and time-saving way by applying modern electronic aids. Though all samples still have to be sorted by species and have to be weighed and measured the introduction of electronic aids, however, like electronic measuring board and computer-aided image processing system, all weight and length data are immediately and digitally recorded after processing. They are transferred via a network to a server PC which stores them into a purpose-designed database. This article describes the applicationof two electronic systems: the measuring board (FM 100, Fa. SCANTROL), iniated by a project in the Norwegian Institute for Fishing Technology, and a computer-aided image processing system, focussing on measuring shrimps in their naturally flexed shape, also developed in the Institute for Fishing Technology in close collaboration with the University of Duisburg. These electronic recording systems allow the consistent and reproducible record of data independent of the changing day-to-day personal form of the staff operating them. With the help of these systems the number of measurements the laboratory could be maximized to 250 000 per year. This made it possible to evaluate, in 1999, 525 catch samples from 75 commercial hauls taken during 15 days at sea. The time gain in measuring the samples is about one third of the time previously needed (i.e. one hour per sample). An additional advantage is the immediate availability of the digitally stored data which enables rapid analyses of all finished subexperiments. Both systems are applied today in several institutes of the Federal Research Centre. The image processing system is now the standard measuring method in an international research project.

Fiabilidad de diferentes pruebas que se utilizan para evaluar el riesgo de lesión del miembro inferior en mujeres deportistas

233 p. : il. + anexo (247 p.)

Factors Resulting In Micron Indentation Hardness Descending In Indentation Tests

Some factors that affect the experimental results in nanoindentation tests such as the contact depth, contact area, load and loading duration are analyzed in this article. Combining with the results of finite element numerical simulation, we find that the creep property of the tested material is one of the important factors causing the micron indentation hardness descending with the increase of indentation depth. The analysis of experimental results with different indentation depths demonstrates that the hardness decrease can be bated if the continuous stiffness measurement technique is not adopted; this indicates that the test method itself may also be one of the factors causing the hardness being descended.

Testing the performance and feasibility of Bluetooth communications in pervasive systems

Smart and mobile environments require seamless connections. However, due to the frequent process of ''discovery'' and disconnection of mobile devices while data interchange is happening, wireless connections are often interrupted. To minimize this drawback, a protocol that enables an easy and fast synchronization is crucial. Bearing this in mind, Bluetooth technology appears to be a suitable solution to carry on such connections due to the discovery and pairing capabilities it provides. Nonetheless, the time and energy spent when several devices are being discovered and used at the same time still needs to be managed properly. It is essential that this process of discovery takes as little time and energy as possible. In addition to this, it is believed that the performance of the communications is not constant when the transmission speeds and throughput increase, but this has not been proved formally. Therefore, the purpose of this project is twofold: Firstly, to design and build a framework-system capable of performing controlled Bluetooth device discovery, pairing and communications. Secondly, to analyze and test the scalability and performance of the \emph{classic} Bluetooth standard under different scenarios and with various sensors and devices using the framework developed. To achieve the first goal, a generic Bluetooth platform will be used to control the test conditions and to form a ubiquitous wireless system connected to an Android Smartphone. For the latter goal, various stress-tests will be carried on to measure the consumption rate of battery life as well as the quality of the communications between the devices involved.

WEFTA interlaboratory comparison on nitrogen determination by Kjeldahl digestion in fishery products and standard substances

14 Laboratorien aus 12 europäischen Ländern nahmen an einer Laborvergleichsuntersuchung zur Stickstoffbestimmung in Fischerzeugnissen und Standardsubstanzen nach Kjeldahl teil. 13 Laboratorien erzielten dabei Ergebnisse, die alle in engen Grenzen um die gefundenen Mittelwerte streuten. Der von den einzelnen Teilnehmern erzielte Variationskoeffizient war mit etwa 0,5 % gering. Auch die Standardsubstanzen mit bekanntem Stickstoffgehalt konnten überwiegend mit hinreichender Genauigkeit (98 % der vom Hertsteller angegebenen Gehalte) analysiert werden. Der ideale Kjeldahlaufschluß ist durch kurze Aufschlußzeiten (ca. 120 min), eine Aufschlußtemperatur bei 430° C und durch die Wahl des für die jeweilige Matrix geeigneten Katalysators gekennzeichnet.

Deviation from standard inflationary cosmology and the problems in ekpyrosis

There are two competing models of our universe right now. One is Big Bang with inflation cosmology. The other is the cyclic model with ekpyrotic phase in each cycle. This paper is divided into two main parts according to these two models. In the first part, we quantify the potentially observable effects of a small violation of translational invariance during inflation, as characterized by the presence of a preferred point, line, or plane. We explore the imprint such a violation would leave on the cosmic microwave background anisotropy, and provide explicit formulas for the expected amplitudes $\langle a_{lm}a_{l'm'}^*\rangle$ of the spherical-harmonic coefficients. We then provide a model and study the two-point correlation of a massless scalar (the inflaton) when the stress tensor contains the energy density from an infinitely long straight cosmic string in addition to a cosmological constant. Finally, we discuss if inflation can reconcile with the Liouville's theorem as far as the fine-tuning problem is concerned. In the second part, we find several problems in the cyclic/ekpyrotic cosmology. First of all, quantum to classical transition would not happen during an ekpyrotic phase even for superhorizon modes, and therefore the fluctuations cannot be interpreted as classical. This implies the prediction of scale-free power spectrum in ekpyrotic/cyclic universe model requires more inspection. Secondly, we find that the usual mechanism to solve fine-tuning problems is not compatible with eternal universe which contains infinitely many cycles in both direction of time. Therefore, all fine-tuning problems including the flatness problem still asks for an explanation in any generic cyclic models.

A theoretical and empirical study of addiction

Consumption of addictive substances poses a challenge to economic models of rational, forward-looking agents. This dissertation presents a theoretical and empirical examination of consumption of addictive goods.

The theoretical model draws on evidence from psychology and neurobiology to improve on the standard assumptions used in intertemporal consumption studies. I model agents who may misperceive the severity of the future consequences from consuming addictive substances and allow for an agent's environment to shape her preferences in a systematic way suggested by numerous studies that have found craving to be induced by the presence of environmental cues associated with past substance use. The behavior of agents in this behavioral model of addiction can mimic the pattern of quitting and relapsing that is prevalent among addictive substance users.

Chapter 3 presents an empirical analysis of the Becker and Murphy (1988) model of rational addiction using data on grocery store sales of cigarettes. This essay empirically tests the model's predictions concerning consumption responses to future and past price changes as well as the prediction that the response to an anticipated price change differs from the response to an unanticipated price change. In addition, I consider the consumption effects of three institutional changes that occur during the time period 1996 through 1999.