Mean-Variance Hedging Under Multiple Defaults Risk

We solve a mean-variance hedging problem in an incomplete market where multiple defaults can occur. For this purpose, we use a default-density modeling approach. The global market information is formulated as a progressive enlargement of a default-free Brownian filtration, and the dependence of the default times is modelled using a conditional density hypothesis. We prove the quadratic form of each value process between consecutive default times and recursively solve systems of coupled quadratic backward stochastic differential equations (BSDEs). We demonstrate the existence of these solutions using BSDE techniques. Then, using a verification theorem, we prove that the solutions of each subcontrol problem are related to the solution of our global mean-variance hedging problem. As a byproduct, we obtain an explicit formula for the optimal trading strategy. Finally, we illustrate our results for certain specific cases and for a multiple defaults case in particular.     

La3B6O13(OH): The First Acentric High-Pressure Borate Displaying Edge-Sharing BO4 Tetrahedra

La₃B₆O₁₃(OH) was obtained by a high-pressure/high-temperature experiment at 6 GPa and 1673 K. The compound crystallizes in the space group P2₁ (no. 4) with the lattice parameters a=4.785(2), b=12.880(4), c=7.433(3) Å, and β=90.36(10)°, and is built up of corner- as well as edge-sharing BO₄ tetrahedra. It represents the first acentric high-pressure borate containing these B₂O₆ entities. The compound develops borate layers of „sechser“-rings with the La³⁺ cations positioned between the layers. Single-crystal and powder X-ray diffraction, vibrational and MAS NMR spectroscopy, second-harmonic generation (SHG) and thermoanalytical measurements, as well as computational methods were used to affirm the proposed structure and the B₂O₆ entities.     

On the formation and technical importance of the microsegregation in austenitic chromium-nickel alloyed steels

The austenitic chromium nickel alloyed steels are showing different types of concentration-distributions of the elements chromium and nickel in the austenite in dependance on the content of alloys. As a consequence of the crystallization of the heat to austenite the “equal directed” type of segregation forms. The ferritic solidification of a heat and the following ferrite to austenite transformation leads to “unequal directed” segregation in the austenite. Heats having both the types of segregation solidify by way a 3-phase reaction. For heats ferritically solidified better hot plasticity, lower susceptibility to hot cracking in the weld and better polishability is observed compared with heats solidified austenitically. The advantages are accounted to the lower separation during the ferritic solidification as consequence of the higher diffusivity of the alloying and accompanying elements in the ferrite compared with the austenite.     

Growth and Characterization of GaP Substrates for Liquid Phase Epitaxy

GaP light-emitting diodes were prepared by a single LPE process on LEC and SSD substrates. Red LEDs with a maximal efficiency of 5% could be grown reproducibly on SSD substrates with grains. The effciency of the best LEDs on substrates grown by the conventional LEC method is essentially lower (0.5%) but it can be improved considerably by a modification of the growth conditions. The substrates were characterized by structural, chemical, electrical and optical measurements and the observed differences in the luminescence efficiency between the LEDs grown on LEC and SSD subtrates, respectively, were discussed under consideration of these investigations.     

Anomalous Geomagnetic Signal Emphasized before the Mw8.2 Coastal Alaska Earthquake,Occurred on 29 July 2021

A very strong earthquake of magnitude Mw8.2 struck the coastal zone of Alaska (USA), on 29 July 2021. This earthquake was felt around the Gulf of Alaska, on a wide offshore area belonging to USA and Canada. In order to identify an anomalous geomagnetic signal before the onset of this earthquake, we retrospectively analyze the data collected on the interval 17 June–31 July 2021, via internet, at the two geomagnetic observatories, College (CMO)—Alaska and Newport (NEW)—USA, by using the polarization parameter (BPOL) and the strain effect related to geomagnetic signal identification. Thus, for both observation sites (CMO and NEW), the daily mean distribution of the BPOL and its standard deviation (STDEV) are carried out using an FFT band-pass filtering in the ULF range (0.001–0.0083 Hz). Further on, a statistical analysis based on a standardized random variable equation is applied to emphasize the following: (a) the anomalous signature related to Mw8.2 earthquake on the both time series BPOL*(CMO) and BPOL*(NEW); (b) the differentiation of the transient local anomalies associated with Mw8.2 earthquake from the internal and external parts of the geomagnetic field, taking the NEW observatory as reference. Finally, on the BPOL*(NEW-CMO) time series, carried out on the interval 7–31 July 2021, a very clear anomaly of maximum, greater than 1.2 STDEV, was detected on 22 July, with 7 days before the onset of the Mw8.2 earthquake.     

Facile, Novel Methodology for the Synthesis of Spiro

The role of the bifunctional catalyst is decisive: The magnesium ion as Lewis acid and its nucleophilic iodide counterion contribute in synergy to the successful ring expansion of the cyclopropane 1 by aldimine 2 [Eq. (1)]. This reaction offers a novel route to spiro[pyrrolidin-3,3'-oxindoles] 3.     

Untersuchungen an Metallkatalysatoren. XXVII. Zum Einfluß verschiedener Träger auf die Dispersität von Nickel

Investigations on Metal Catalysts. XXVII. On the Influence of Several Carriers on the Dispersion of Nickel Nickel supported catalysts (carrier: η-, ?-, α-Al₂O₃, TiO₂) were characterized by chemically determined degree of reduction, CO chemisorption, magnetic susceptibility measurements and FMR. The influence of interaction between carrier and active component in the unreduced state on the size and number of Ni crystallites is discussed.