Finite-range DWBA analyses of (dt) and (d3He) reactions on 64Zn at Ed = 13 MeV

Exact finite-range DWBA analyses of ($\text{d}\text{, t}\text{)}$ and $\text{(}\text{d}\text{d}$, ³He) reactions have been performed for an ⁶⁴Zr target at an incident deuteron energy of 13.0 MeV, leading to the ground states of the residual nuclei. The microscopic overlap functions for (d, t) and (d, ³He) systems obtained by using the Phillips triton wavefunctions have been used as projectile form factors into the calculation. The results are compared with zero-range DWBA calculations taking the finite-range effects into account by means of a local energy approximation. The results obtained by finite-range and zero-range calculations for differential cross sections as well as vector and tensor analysing powers are compared with the experimental data. The range of validity of the local energy approximation is discussed.     

Gravitational collapse in higher-dimensional charged-Vaidya space-time

We analyze here the gravitational collapse of higher-dimensional charged-Vaidya spacetime. We show that singularities arising in a charged null fluid in higher dimension are always naked violating at least strong cosmic censorship hypothesis (CCH), though not necessarily weak CCH. We show that earlier conclusions on the occurrence of naked singularities in four-dimensional case can be extended essentially in the same manner in 5D case also     

Mass spectral fragmentation pattern of 3-methyl- and 3-phenyl-4-(N-methylarylhydrazono)isoxazol-5-ones

3-Methyl-4-(N-methylarylhydrazono)isoxazol-5-ones and 3-phenyl-4-(N-methylarylhydrazono)isoxazol-5-ones undergo considerable fragmentation on electron impact involving rupture of the isoxazolone ring and bonds in the N-methylarylhydrazono side chain.     

A single server queue in a hard-real-time environment

We consider a single server first in first out queue in which each arriving task has to be completed within a certain period of time (its deadline). More precisely, each arriving task has its own deadline - a non-negative real number - and as soon as the response time of one task exceeds its deadline, the whole system in considered to have failed. (In that sense the deadline is hard.) The main practical motivation for analyzing such queues comes from the need to evaluate mathematically the reliability of computer systems working with real time constraints (space or aircraft systems for instance). We shall therefore be mainly concerned with the analytical characterization of the transient behavior of such a queue in order to determine the probability of meeting all hard deadlines during a finite period of time (the ‘mission time’). The probabilistic methods for analyzing such systems are suggested by earlier work on impatience in telecommunication systems [1,2].     

Two queues with alternating service and server breakdown

We consider a queueing system with two stations served by a single server in a cyclic manner. We assume that at most one customer can be served at a station when the server arrives at the station. The system is subject to service interuption that arises from server breakdown. When a server breakdown occurs, the server must be repaired before service can resume. We obtain the approximate mean delay of customers in the system.     

Vibrational dynamics of polyurydilic acid

A study of the normal modes of vibration and their dispersion in polyurydilic acid (polyU) is reported using Wilson's GF Matrix method as modified by Higgs. This is done for the `bare' as well as for the helix `loaded' with uracil. Confusion that has prevailed regarding the assignments of the observed modes at 810 and 572 cm⁻¹ is cleared and it is shown that the so called bare helix (polyU-U) has a different minimum energy state and hence spectrally different. Dispersion of the normal modes in the two helices shows marked differences which are characteristic of the extent of electrical/mechanical coupling along the chain and between the chain and the base. Values predicted for the heat capacity as a function of temperature for polyU is also reported.     

Synthesis of a novel indolobenzodiazepine

2-[(5-Methyl-1,3,4-oxadiazol-2-yl)methyl]benzenamine ( 15 ) was prepared in four steps from o-nitrophenyl-acetic acid, and treated with triethyl orthoformate in an attempt to prepare an oxadiazolobenzodiazepine. However, the resulting product was 13-(5-methyl-1,3,4-oxadiazol-2-yl)-5H-indolo[2,1-b][1,3]benzodiazepine monohydrate ( 16 ). Indolobenzodiazepine 16 is the first reported member of a novel ring system. Interesting features of the synthesis of 16 are discussed, including the mechanism of formation from 15.     

Mass spectral fragmentation pattern of 2,3-dimethyl- and 2-methyl-3-phenyl-4-arylazoisoxazol-5-ones

2,3-Dimethyl-4-arylazoisoxazol-5-ones and 2-methyl-3-phenyl-4-aryiazoisoxazol-5-ones undergo considerable fragmentation on electron impact. The base peaks in the mass spectra are at mass 56 and 118 respectively attributed to the N-methylacetonitrile cation and the N-methylbenzonitrile cation.     

A reinvestigation of the cyclodesulfurization of thiosemicarbazides

A recent report describing the preparation of 2-(substituted-amino)-3,4-dihydro-5H-1,3,4-benzotriazepin-5-ones (3), by the cyclodesulfurization of hydrazides prepared from o-aminobenzoylhydrazine ( 1 ) and isothiocyanates, is erroneus. The products resulting from this reaction sequence are, instead, 2-(substituted-amino)-5-(o-aminophenyl)-1,3,4-oxadiazoles ( 4 ). Alternate syntheses of the oxadiazoles led to the correct structural assignments.