Evidence for a kaon-bound state K(-)pp produced in K(-) absorption reactions at rest

We have searched for a deeply bound kaonic state by using the FINUDA spectrometer installed at the e(+)e(-) collider DAPhiNE. Almost monochromatic K(-)'s produced through the decay of phi(1020) mesons are used to observe K(-) absorption reactions stopped on very thin nuclear targets. Taking this unique advantage, we have succeeded to detect a kaon-bound state K(-)pp through its two-body decay into a Lambda hyperon and a proton. The binding energy and the decay width are determined from the invariant-mass distribution as 115(+6)(-5)(stat)(+3)(-4)(syst) MeV and 67(+14)(-11)(stat)(+2)(-3)(syst) MeV, respectively.     

Third harmonics of the AC magnetic susceptibility: a method for the study of flux dynamics in high temperature superconductors

The temperature dependence of the 1st and 3rd harmonics ( ) of the AC magnetic susceptibility has been measured on melt grown YBCO samples for different frequencies and amplitudes of the AC magnetic field and intensity of a contemporaneously applied DC field. With the help of critical state models and of numerical simulations [22], we have devised a novel method, based on the combined analysis of the 1st and the 3rd harmonics (specifically on the comparison between and ), that allows to distinguish different temperature ranges dominated by the different dissipative magnetic flux regimes. In particular, we identified three principal zones in the temperature dependence of the real part of the 3rd harmonic: the zone 1, in the temperature range below the peak of the imaginary part of the 1st harmonic, , and the zone 2, characterized by negative values in a temperature region just above , both dominated by the creep regime; the zone 3, just below T _c , in which we revealed the presence of Thermally Assisted Flux Flow (TAFF). By the identification of these zones, an estimation of the value of the pinning potential can be obtained.Received: 23 September 2003, Published online: 19 November 2003PACS: 74.25.Ha Magnetic properties - 74.60.Ge Flux pinning, flux creep, and flux-line lattice dynamics     

Interaction of regular and chaotic states

Modelling the chaotic states in terms of the Gaussian Orthogonal Ensemble of random matrices (GOE), we investigate the interaction of the GOE with regular bound states. The eigenvalues of the latter may or may not be embedded in the GOE spectrum. We derive a generalized form of the Pastur equation for the average Green’s function. We use that equation to study the average and the variance of the shift of the regular states, their spreading width, and the deformation of the GOE spectrum non-perturbatively. We compare our results with various perturbative approaches.     

Morphological and chemical characterization of weathering products on buried Sasanian glass from central Iraq

This paper discusses the morphological and chemical features of the weathering products on Sasanian glass finds excavated at the ancient Sasanian town of Veh Arda?īr, some 30 km south of Baghdad (Iraq), and dated from the third to the sixth century. All the considered fragments represent soda-lime glass, with MgO contents between 3% and 8%, resulting from the use of soda-rich plant ash as a flux; within this general frame, two productions can be distinguished due to their MgO to K₂O ratio. Four main alteration typologies were observed by visual examination of the excavated samples; these were studied by scanning electron microscopy, energy dispersive X-ray analysis, inductively coupled plasma-mass spectrometry, X-ray diffraction and thermal analysis. Different alteration features were generally observed for samples belonging to the two compositional groups. In particular, samples with higher MgO to K₂O ratios show definitely thinner crusts, associated with alteration plugs going down into the glass. Moreover, gray or black crusts are related to the presence of manganese at significant levels in the original glass.     

Preparing Pre‐Service Teachers to Teach Mathematics in Inclusive Classrooms: A Three‐Year Case Study

Federal and state regulations mandating inclusion of students with disabilities in general education classes have made it essential to create pathways for pre‐service teachers to develop skills to teach content to diverse groups of students. The study uses a framework suggested by the relationship between teacher attitude and teacher behavior ( Fullan, 1982 ), teacher beliefs and practice, and self‐efficacy and behavioral change ( Bandura, 1977 ). The purpose of the study was to examine changes, if any, in three cohorts of general education teacher candidates' (n=13, n=8, n=5) attitudes toward teaching mathematics to students with disabilities after participating in focused instructional experiences which provided both information and vicarious positive teaching activities in special education. Data collected included pretest and posttest scores for each of the three cohorts and journal entries. Little or no change in attitude towards students with disabilities and mathematics, and efficacy to teach students with disabilities was observed for the year one and year two cohorts. In the third year the modules were combined with a structured field experience. The data collected from the third year cohort suggested a positive trend in attitude as measured by the survey data and field experience journal data. Future study with larger samples is needed.     

Enantioselective epoxide polymerization using a bimetallic cobalt catalyst

A highly active enantiopure bimetallic cobalt complex was explored for the enantioselective polymerization of a variety of monosubstituted epoxides. The polymerizations were optimized for high rates and stereoselectivity, with s-factors (k(fast)/k(slow)) for most epoxides exceeding 50 and some exceeding 300, well above the threshold for preparative utility of enantiopure epoxides and isotactic polyethers. Values for mm triads of the resulting polymers are typically greater than 95%, with some even surpassing 98%. In addition, the use of a racemic catalyst allowed the preparation of isotactic polyethers in quantitative yields. The thermal properties of these isotactic polyethers are presented, with many polymers exhibiting high T(m) values. This is the first report of the rapid synthesis of a broad range of highly isotactic polyethers via the enantioselective polymerization of racemic epoxides.