A geometric approach to time evolution operators of Lie quantum systems

Lie systems in Quantum Mechanics are studied from a geometric point of view. In particular, we develop methods to obtain time evolution operators of time-dependent Schrodinger equations of Lie type and we show how these methods explain certain ad hoc methods used in previous papers in order to obtain exact solutions. Finally, several instances of time-dependent quadratic Hamiltonian are solved.Comment: Accepted for publication in the International Journal of Theoretical Physic

Relativistic wave equations for interacting massive particles with arbitrary half-intreger spins

New formulation of relativistic wave equations (RWE) for massive particles with arbitrary half-integer spins s interacting with external electromagnetic fields are proposed. They are based on wave functions which are irreducible tensors of rank $n ($n=s-\frac12$) antisymmetric w.r.t. n pairs of indices, whose components are bispinors. The form of RWE is straightforward and free of inconsistencies associated with the other approaches to equations describing interacting higher spin particles

Small-scale solar magnetic fields

As we resolve ever smaller structures in the solar atmosphere, it has become clear that magnetism is an important component of those small structures. Small-scale magnetism holds the key to many poorly understood facets of solar magnetism on all scales, such as the existence of a local dynamo, chromospheric heating, and flux emergence, to name a few. Here, we review our knowledge of small-scale photospheric fields, with particular emphasis on quiet-sun field, and discuss the implications of several results obtained recently using new instruments, as well as future prospects in this field of research.Comment: 43 pages, 18 figure

Microbiological quality of shrimp imported from South-East Asia

Van de rauwe garnalen (15 monsters) varieerden de aerobe kiemgetallen van < 10-3 tot 10-6, de Enterobacteriaceae kiemgetallen van < 10 tot 10-2 en de S.aureus kiemgetallen van < 10 tot 10-3. In 4 monsters werd E.coli aangetoond, in een monster Salmonella en in een ander monster NAG-Vibrio. Van de niet-doorstraalde gepelde gekookte garnalen (54 monsters) varieerden de aerobe kiemgetallen van < 10-3 tot 10-7, de Enterobacteriaceae kiemgetallen van < 10 tot 10-2 en de S.aureus kiemgetallen van < 10 tot 10-4. In 11 monsters werd E.coli aangetoond, in 3 monsters Salmonella en in 1 monster NAG-Vibrio. In doorstraalde gepelde gekookte garnalen (7 monsters) waren de aerobe kiemgetallen steeds < 10-5 en de Enterobacteriaceae en S.aureus kiemgetallen < 10. De aanwezigheid van Shigella op gepelde gekookte garnalen afkomstig uit Zuid-Oost Azie blijft een potentieel risico voor de volksgezondheid.Abstract not availableHI

The effect of irradiation on spoilage organisms and shelf-life of bami and nasi goreng

Het doorstralen met 2,5 kGy resulteerde zowel met bami goreng als met nasi goreng in een reductie van het aeroob kiemgetal met 5 logeenheden. De Gram-negatieve flora nam sterker af dan de Gram-positieve. De overlevende flora bestond vooral uit Gram-positieve coccen. Tijdens bewaren bij 7 graden C nam het aeroob kiemgetal van doorstraalde nasi goreng niet, en van doorstraalde bami goreng slechts zeer langzaam toe. Er wordt geconcludeerd dat doorstraling leidt tot een verlenging van de houdbaarheid van bami en nasi.Abstract not availableHI

<i>Listeria monocytogenes</i>: heat resistance and behaviour during storage of milk and whey and making of Dutch types of cheese

The heat resistance of Listeria monocytogenes suspended in milk was determined with a plate pasteurizer and glass capillary tubes. The reduction of the, number of Listeria obtained by the plate pasteurizer was ,,;5 log 10 units at 64.0 °C for 10 s and 6-7 log 10 units at 67.0 °C for 10 s. The heat resistance of freely suspended and phagocyted Listeria was investigated with glass cap­illary tubes. The surviving Listeria were determined with and without resuscitation at 4 °C. Using the resuscitation method it appeared that phagocytosis did increase the heat resistance of one of the two tested Listeria strains by factor 2. With the resuscitation method up to 30 times more Lis­teria could be recovered than without resuscitation. The estimated decimal reduction times for the most heat-resistant strain was about 17 sat 64.0 °C and 8 sat 66.0 °C. Incubation tests of L. monocytogenes in raw and HTST-pasteurized milk (15 s 72 °C) at 4 and 7 °C showed some injury of Listeria during the first 1-2 days. Thereafter growth commenced. In intensively pasteurized milk (30 min 98 °C) Listeria was not injured. Gouda and Maasdam types of cheese were made from Listeria-contaminated milk. During the manufacture Listeria was concentrated in the curd by factor 10, and a limited growth occurred. During 6 weeks of ripening at 13 °C the number of Listeria was almost constant

Treatment of negative dysphotopsia with supplementary implantation of a sulcus-fixated intraocular lens

PURPOSE: Our aim was to evaluate the resolution of negative dysphotopsia supplementary implantation of a sulcus-fixated intraocular lens (IOL). This was a retrospective case series. Patients with severe negative were treated with supplementary implantation of the Rayner Sulcoflex (653 L) IOL. Primary outcome measurements were subjectively reported of dysphotopsia, best corrected distance visual acuity (CDVA), iris-IOL anterior chamber depth (ACD) and volume (ACV), angle opening distance trabecular-iris space area at 500 and 750 mum. RESULTS: A Rayner was implanted in seven patients (nine eyes) with negative dysphotopsias. resolved completely in six eyes, partially in one eye and remained two eyes. We did not find any significant changes in CDVA. Angle opening distance, ACD, ACV and iris-IOL distance reduced significantly after IOL implantation. CONCLUSIONS: Supplementary implantation of a Sulcoflex successfully treat negative dysphotopsia. The decrease in anterior dimensions in combination with the displacement of light rays by the edges of a Sulcoflex IOL may contribute to the resolution of symptoms

<i>Listeria monocytogenes</i>: heat resistance and behaviour during storage of milk and whey and making of Dutch types of cheese

The heat resistance of Listeria monocytogenes suspended in milk was determined with a plate pasteurizer and glass capillary tubes. The reduction of the, number of Listeria obtained by the plate pasteurizer was ,,;5 log 10 units at 64.0 °C for 10 s and 6-7 log 10 units at 67.0 °C for 10 s. The heat resistance of freely suspended and phagocyted Listeria was investigated with glass cap­illary tubes. The surviving Listeria were determined with and without resuscitation at 4 °C. Using the resuscitation method it appeared that phagocytosis did increase the heat resistance of one of the two tested Listeria strains by factor 2. With the resuscitation method up to 30 times more Lis­teria could be recovered than without resuscitation. The estimated decimal reduction times for the most heat-resistant strain was about 17 sat 64.0 °C and 8 sat 66.0 °C. Incubation tests of L. monocytogenes in raw and HTST-pasteurized milk (15 s 72 °C) at 4 and 7 °C showed some injury of Listeria during the first 1-2 days. Thereafter growth commenced. In intensively pasteurized milk (30 min 98 °C) Listeria was not injured. Gouda and Maasdam types of cheese were made from Listeria-contaminated milk. During the manufacture Listeria was concentrated in the curd by factor 10, and a limited growth occurred. During 6 weeks of ripening at 13 °C the number of Listeria was almost constant