Estudo quantitativo e qualitativo dos plexos de Auerbach e Meissner do esôfago de cães inoculados com o Trypanosoma cruzi

Foi realizado um estudo quantitativo e qualitativo dos plexos de Auerbach e Meissner do esôfago de quatro cães chagásicos sacrificados na fase aguda da infecção. As ganglionites e periganglionites do plexo de Auerbach variaram de discretas a moderadas, induzindo lesões neuronais significativas, principalmente em dois animais. Os gânglios do plexo de Meissner foram observados em pequeno número, impossibilitando qualquer análise. Miosite discreta ou moderada foi observada principalmente no terço inferior do esôfago, raramente associada a ninhos de amastigotas. A contagem de gânglios e neurônios não demonstrou desnervação. Apesar de em nenhum dos cães ter sido induzida a formação de megaesôfago, relatamos lesões do plexo de Auerbach e de miocélulas do esôfago de animais na fase aguda da infecção chagásica. Este parece ser o primeiro estudo quantitativo e qualitativo sistemático dos plexos de Auerbach e Meissner do esôfago na tripanosomíase cruzi experimental.

Meissner effect and critical fields in an inhomogeneous Ba2HoCu3O7-x high-Tc superconductor

The Meissner and diamagnetic shielding effects and the upper, lower, and thermodynamical critical fields have been studied in a Ba2HoCu3O7-x sample using magnetization measurements in fields up to 55 kOe. The diamagnetic shielding curve shows the existence of a transition at Tc=91.5 K followed by a broad transition extending from 85 to 25 K which may be related to inhomogeneities in the oxygen content of the sample. A rather low flux expulsion (13.5%) is observed which we attribute to flux pinning or trapping. We show that the coexistence of superconducting and nonsuperconducting regions within the sample at temperatures just below Tc leads to strong reductions in the critical magnetic fields.

Vern Ummel and Irvin C. (Ernie) Chapman at the Chapman College 124th Anniversary, 1985.

Vern Ummel and Irvin C. (Ernie) Chapman at the Chapman College 124th Anniversary, Orange, California, March 4, 1985.

Irvin [Ernie] Clarke Chapman in California Christian College football uniform. Los Angeles, California, 1930

Irvin [Ernie] Clarke Chapman in football uniform on the campus of California Christian College, Los Angeles, California, 1930.

Cecilia and Randall Presley, Irvin C. "Ernie" Chapman, and C. James Beneley at a Chapman College event in 1983

Honorees [left to right] Cecilia and Randall Presley, Irvin C. "Ernie" Chapman, and C. James Beneley at a Chapman College event in 1983. Cecilia Presley is the granddaughter of Cecil B. DeMille. [Chapman Quarterly, Winter 1983]

Stan and Carol Chapman stand behind Edy and Ernie Chapman

Chapman College trustees, left to right [above] Stan and Carol Chapman; [seated] Edy and Ernie Chapman at a dinner event.

Coach Ken Visser, Matt Hertzler and; Ernie Chapman

Football coach Ken Visser, Matt Hertzler and Ernie Chapman. Hertzler was awarded ESPN the Magazine Academic All-District VIII Offensive line in 1997 and All-American Offensive Line in 1997 and 1998.

Irvin C. (Ernie) Chapman at the Chapman College 124th Anniversary, Orange, California, March 4, 1985.

Irvin C. (Ernie) Chapman at the Chapman College 124th Anniversary, Orange, California, March 4, 1985.

Liz Lin and Irvin C. (Ernie) Chapman at the Chapman College 124th Anniversary, Orange, California, March 4, 1985

Liz Lin and Irvin C. (Ernie) Chapman at the Chapman College 124th Anniversary, Orange, California, March 4, 1985.

Irvin C. (Ernie) Chapman at the Chapman College 124th Anniversary, Orange, California, March 4, 1985.

Irvin C. (Ernie) Chapman at the Chapman College 124th Anniversary, Orange, California, March 4, 1985.

Irvin C. (Ernie) Chapman at the Chapman College 124th Anniversary, Orange, California, March 4, 1985.

Irvin C. (Ernie) Chapman at the Chapman College 124th Anniversary, Orange, California, March 4, 1985.

President G. T. "Buck" Smith presents Irvin C. "Ernie" Chapman with 50th year diploma at Commencement, 1983

President G. T. "Buck" Smith presents Irvin C. "Ernie" Chapman with 50th year diploma at Commencement, Chapman College, Orange, California, May 29, 1983.

The Effects of Annealing URu2Si2 on the Resistivity and Meissner Effect

The enigmatic heavy fermion URu2Si2, which is the subject of this thesis, has attracted intensive theoretical and experimental research since 1984 when it was firstly reported by Schlabitz et al. at a conference [1]. The previous bulk property measurements clearly showed that one second order phase transition occurs at the Hidden Order temperature THO ≈ 17.5 K and another second order phase transition, the superconducting transition, occurs at Tc ≈ 1 K. Though twenty eight years have passed, the mechanisms behind these two phase transitions are still not clear to researchers. Perfect crystals do not exist. Different kinds of crystal defects can have considerable effects on the crystalline properties. Some of these defects can be eliminated, and hence the crystalline quality improved, by annealing. Previous publications showed that some bulk properties of URu2Si2 exhibited significant differences between as-grown samples and annealed samples. The present study shows that the annealing of URu2Si2 has some considerable effects on the resistivity and the DC magnetization. The effects of annealing on the resistivity are characterized by examining how the Residual Resistivity Ratio (RRR), the fitting parameters to an expression for the temperature dependence of the resistivity, the temperatures of the local maximum and local minimum of the resistivity at the Hidden Order phase transition and the Hidden Order Transition Width ∆THO change after annealing. The plots of one key fitting parameter, the onset temperature of the Hidden Order transition and ∆THO vs RRR are compared with those of Matsuda et al. [2]. Different media used to mount samples have some impact on how effectively the samples are cooled because the media have different thermal conductivity. The DC magnetization around the superconducting transition is presented for one unannealed sample under fields of 25 Oe and 50 Oe and one annealed sample under fields of 0 Oe and 25 Oe. The DC field dependent magnetization of the annealed Sample1-1 shows a typical field dependence of a Type-II superconductor. The lower critical field Hc1 is relatively high, which may be due to flux pinning by the crystal defects.