Observational Aspects of Symmetries of the Neutral B Meson System

We revisit various results, which have been obtained by the BABAR and Belle Collaborations over the last twelve years, concerning symmetry properties of the Hamiltonian, which governs the time evolution and the decay of neutral B mesons.We find that those measurements, which established CP violation in B meson decay, 12 years ago, had as well established T (time-reversal) symmetry violation. They also confirmed CPT symmetry in the decay (T_CPT = 0) and symmetry with respect to time-reversal (epsilon? = 0) and to CPT (delta? = 0) in the B0 ?B0bar oscillation.Comment: Original arguments and conclusions unchanged. Relation to other work explained in more detail. 2 references adde

A Remark on the Principle of Zero Utility

Let u(x) be a utility function, i.e., a function with u′(x)>0, u″(x)<0 for all x. If S is a risk to be insured (a random variable), the premium P = P(x) is obtained as the solution of the equation which is the condition that the premium is fair in terms of utility. It is clear that an affine transformation of u generates the same principle of premium calculation. To avoid this ambiguity, one can standardize the utility function in the sense that for an arbitrarily chosen point y. Alternatively, one can consider the risk aversion which is the same for all affine transformations of a utility function. Given the risk aversion r(x), the standardized utility function can be retrieved from the formula It is easily verified that this expression satisfies (2) and (3). The following lemma states that the greater the risk aversion the greater the premium, a result that does not surpris

Stop-loss a tempo continuo e protezione dinamica di un fondo d'investimento

Nella prima parte del nostro lavoro, il surplus di una compagnia d'assicurazione è modellizzato come un processo di Wiener. Consideriamo un contratto d'assicurazione dinamica di solvibilità. Secondo questo contratto, i pagamenti necessari sono effettutati istantaneamente, in modo che il surplus modificato non divenga mai negativo. Matematicamente, questo corrisponde ad introdurre una barriera riflettente in zero. Otteniamo così un'espressione esplicita per il premio netto di un tale contratto. Nella seconda parte, consideriamo un fondo d'investimento il cui valore unitario è modellizzato da un moto browniano geometrico. Differenti forme di protezione di fondi d'investimento sono esaminate. La più semplice consiste in una garanzia che fornisce istantaneamente i pagamenti necessari, di modo che il valore unitario modificato del fondo non scenda sotto un determinato livello protetto. Esiste un'espressione esplicita per il prezzo di una tale garanzia. Questo risultato può anche essere utilizzato per valutare il prezzo di una garanzia in cui il livello protetto è una funzione esponenziale del tempo. In più, è dimostrato come sintetizzare questa garanzia, costruendo il portafoglio replicante. La garanzia dinamica di fondi d'investimento è paragonata all'opzione di vendita corrispondente, e si è osservato che per delle scadenze corte, il rapporto dei due prezzi è di circa 2. Infine ci interesseremo al prezzo di una protezione più esotica, nella quale il valore unitario garantito in ogni momento è una frazione fissa del valore unitario modificato massimo osservato fino a quel moment

A note on moments of dividends

We reconsider a formula for arbitrary moments of expected discounted dividend payments in a spectrally negative Lévy risk model that was obtained in Renaud and Zhou (2007, [4]) and in Kyprianou and Palmowski (2007, [3]) and extend the result to stationary Markov processes that are skip-free upward

On optimal investiment strategies

Suppose an investor has a fixed decision horizon and an appropriate utility function for measuring his or her utility of wealth. If there are only two investment vehicles, a risky and a risk-free asset, then the optimal investment strategy is such that, at any time, the amount invested in the risky asset must be the product of his or her "current risk tolerance” and the risk premium on the risky asset, divided by the square of the diffusion coefficient of the risky asset. In the case of more than one risky asset, the optimal investment strategy is similar, with the ratios of the amounts invested in the different risky assets being constant over tim

Circuit de commande pour Anti Collision Lamps ACL

Objectif Les ACL sont des ampoules 28V/200W utilisés dans le domaine de l’éclairage professionnel. Habituellement, 8 ampoules sont branchées en série sur le réseau. Suite à ce montage, une commande individuelle de la luminosité n’est pas possible. L’appareil conçu dans ce projet met toutes les ampoules en parallèle sur un bus de tension continue à 28Vdc. La commande individuelle est maintenant possible. Une protection anti-courtcircuit est aussi conçue afin de sécuriser l’installation. Pour alimenter le bus de tension continue, un pont H résonnant est utilisé. Pour diminuer au mieux les pertes de ce système, un redresseur actif est utilisé. Ce dernier fonctionne en utilisant la tension induite d’une self saturable. Résultats L’alimentation du bus de tension continue au travers du redresseur actif n’a pas pu être réalisée car le signal de la self saturable n’est pas assez fiable. La protection anti-court-circuit fonctionne correctement. La lampe fait du bruit lorsque celle est alimentée par des flancs de courant trop brusques à des fréquences audibles. La solution consisterait à l’alimenter à des fréquences élevées.Ziel ACLs sind Lampen 28V/200W, welche im Bereich der professionellen Beleuchtung verwendet werden. Normalerweise sind 8 Lampen in Serie am Netz angeschlossen. Durch diese Anordnung ist eine individuelle Lichtsteuerung nicht möglich. Mit dem in diesem Projekt zu entwickelnden Gerät werden alle Lampen parallel auf einen Spannungsbus von 28Vdc gelegt: Dadurch wird die individuelle Ansteuerung ermöglicht. Zur besseren Sicherheit wird auch eine Kurzschlusssicherheit realisiert. Der Spannungsbus wird mittels einer resonanten H-Brückenschaltung verwirklicht. Resultate Der synchrone Gleichrichter konnte nicht getestet werden da die Steuersignalgenerierung mit Sättigungsdrossel nicht zuverlässig funktioniert. Die Kurzschlusssicherheit funktioniert einwandfrei. Im Betrieb der Lampe entsteht ein störendes Geräusch, weil die Ansteuerung mit steilen Stromflanken sich in hörbaren Frequenzen abspielt. Zur Behebung dieses Geräusches können Speisungen mit höheren Schaltfrequenzen verwendet werden

Optimal Dividends in the Dual Model with Diffusion

In the dual model, the surplus of a company is a Lévy process with sample paths that are skip-free downwards. In this paper, the aggregate gains process is the sum of a shifted compound Poisson process and an independent Wiener process. By means of Laplace transforms, it is shown how the expectation of the discounted dividends until ruin can be calculated, if a barrier strategy is applied, and how the optimal dividend barrier can be determined. Conditions for optimality are discussed and several numerical illustrations are given. Furthermore, a family of models is analysed where the individual gain amount distribution is rescaled and compensated by a change of the Poisson paramete

Three Methods to Calculate the Probability of Ruin

The first method, essentially due to GOOVAERTS and DE VYLDER, uses the connection between the probability of ruin and the maximal aggregate loss random variable, and the fact that the latter has a compound geometric distribution. For the second method, the claim amount distribution is supposed to be a combination of exponential or translated exponential distributions. Then the probability of ruin can be calculated in a transparent fashion; the main problem is to determine the nontrivial roots of the equation that defines the adjustment coefficient. For the third method one observes that the probability, of ruin is related to the stationary distribution of a certain associated process. Thus it can be determined by a single simulation of the latter. For the second and third methods the assumption of only proper (positive) claims is not neede

Peripheral nerve-derived VEGF promotes arterial differentiation via neuropilin 1-mediated positive feedback

In developing limb skin, peripheral nerves are required for arterial differentiation, and guide the pattern of arterial branching. In vitro experiments suggest that nerve-derived VEGF may be important for arteriogenesis, but its role in vivo remains unclear. Using a series of nerve-specific Cre lines, we show that VEGF derived from sensory neurons, motoneurons and/or Schwann cells is required for arteriogenesis in vivo. Arteriogenesis also requires endothelial expression of NRP1, an artery-specific coreceptor for VEGF^(164) that is itself induced by VEGF. Our results provide the first evidence that VEGF is necessary for arteriogenesis from a primitive capillary plexus in vivo, and show that in limb skin the nerve is indeed the principal source of this signal. They also suggest a model in which a `winner-takes-all' competition for VEGF may control arterial differentiation, with the outcome biased by a VEGF^(164)-NRP1 positive-feedback loop. Our results also demonstrate that nerve-vessel alignment is a necessary, but not sufficient, condition for nerve-induced arteriogenesis. Different mechanisms therefore probably underlie these endothelial patterning and differentiation processes

The optimal dividend barrier in the Gamma-Omega model

In the traditional actuarial risk model, if the surplus is negative, the company is ruined and has to go out of business. In this paper we distinguish between ruin (negative surplus) and bankruptcy (going out of business), where the probability of bankruptcy is a function of the level of negative surplus. The idea for this notion of bankruptcy comes from the observation that in some industries, companies can continue doing business even though they are technically ruined. Assuming that dividends can only be paid with a certain probability at each point of time, we derive closed-form formulas for the expected discounted dividends until bankruptcy under a barrier strategy. Subsequently, the optimal barrier is determined, and several explicit identities for the optimal value are found. The surplus process of the company is modeled by a Wiener process (Brownian motion