Search

The 1501/1401 vibronic two-photon cross section ratios are reported for a series of isotopically labeled benzenes in the A(1B2u)←X(1A1g) electronic transition. Predictions derived from the B2u force field are found to be in close agreement with the measured ratios. These ratios are shown to provide an excellent test of the B2u force field and mode forms as evidenced by the large variation over D6h labeled benzenes. In C6H6 the 1501/1401 cross section ratio is measured as 0.249±0.008 (equivalent to 0.180 for the theoretically testable ratio: 1501/1401[<1|Q14|0>/<1| Q15|0>]2). The corresponding ratio in 13 C6H6 is 0.44±0.04 (equivalent to 0.36). The 13% disparity found between the measured and predicted C6H6 ratio (i.e., 0.206) is attributed to anharmonic coupling between the b2u modes: 2χ15,15=-9, χ14,15=4, and 2χ14,14=-4 cm-1. Two-photon intensities are proven to be useful in determining anharmonic interactions. The relatively small effects of the hydrogen motion provide an approach for solving the bifurcated B2u force constant problem in ground state benzene. The approach utilizes the contribution of harmonic C–C–H bending motions to the two-photon tensor controlling the 1501 and 1401 vibronic cross sections. This requires knowledge of the sign of the hydrogen motion term in the tensor. However, large anharmonic effects coupling the two b2u modes mask the small harmonic hydrogen contribution. [ABSTRACT FROM AUTHOR]

Harmonic ground state frequencies for the a2g mode, ν3, in C6H6, C6D6, and 13C6H6 have been determined by application of the Teller–Redlich product rule to b2u mode frequencies obtained from two-photon fluorescence excitation experiments for the D6h symmetry molecules and a′2 frequencies from 1,3,5-C6H3D3 determined at rotational contour resolution. The a2g harmonic frequency values are 1366.6 cm-1 for C6H6, 1063.0 cm-1 for C6D6, and 1355.4 cm-1 for 13C6H6. The anharmonic correction to ν3 in C6H6, estimated from the difference in product rule and infrared frequencies is -17 cm-1. The b2u mode frequencies, ν14 and ν15, respectively, have also been significantly modified from those obtained from lower resolution spectra to 1309.4 and 1149.7 cm-1 in C6H6, 1286.3 and 827.9 cm-1 (harmonic value) in C6D6, and 1269.8 and 1138.1 cm-1 in 13C6H6. The anharmonic correction for ν15 in C6D6 is estimated as -4 cm-1. The B2u←A1g electronic origin of 13C6H6, has been determined for the first time as 38 105.5±0.3 cm-1. The B2u←A1g electronic origin of 1,3,5-C6H3D3 has been redetermined to be 38 187.5±0.3 cm-1, 3.5 cm-1 higher than previously reported. [ABSTRACT FROM AUTHOR]

For a positive integer and a finite set of finite algebras, let denote the largest -generated subdirect product whose subdirect factors are algebras in . When is the set of all -generated subdirectly irreducible algebras in a locally finite variety , then is the free algebra on free generators for . For a finite algebra the algebra is the largest -generated subdirect power of . For every and finite we provide an upper bound on the cardinality of . This upper bound depends only on and these basic parameters: the cardinality of the automorphism group of , the cardinalities of the subalgebras of , and the cardinalities of the equivalence classes of certain equivalence relations arising from congruence relations of . Using this upper bound on -generated subdirect powers of , as ranges over the -generated subdirectly irreducible algebras in , we obtain an upper bound on . And if all the -generated subdirectly irreducible algebras in have congruence lattices that are chains, then we characterize in several ways those for which this upper bound is obtained. [ABSTRACT FROM AUTHOR]

A congruence relation θ on an algebra A is fully invariant if every endomorphism of A preserves θ. A congruence θ is verbal if there exists a variety $${\mathcal{V}}$$ such that θ is the least congruence of A such that $${{\bf A}/\theta \in \mathcal{V}}$$ . Every verbal congruence relation is known to be fully invariant. This paper investigates fully invariant congruence relations that are verbal, algebras whose fully invariant congruences are verbal, and varieties for which every fully invariant congruence in every algebra in the variety is verbal. [ABSTRACT FROM AUTHOR]

The G-spectrum of a class of algebras is the function that counts, up to isomorphism, the number of at most k-generated algebras in the class, for k = 1, 2, …. We consider the G-spectra of the varieties of algebras generated by a single two-element algebra. We show that such spectra are either polynomial, exponential, or at least doubly exponential as a function of k. For the varieties that have polynomial or exponential G-spectra we provide an exact formula for the function. [ABSTRACT FROM AUTHOR]

Revascularization of an acutely ischemic limb may lead to the development of a reperfusion syndrome, characterized by acidosis, hyperkalemia, myogloe binuria, and disseminated intravascular coagulation. The authors evaluated the components of the lemon) venous efflux after reperfusion of an acutely ischemic limb in both an experimental model and in a small clinical series. [ABSTRACT FROM AUTHOR]

A patient with evidence of both heparin-related thrombocytopenia and coumarin-induced skin necrosis is presented. Etiology, diagnostic evaluation, histopathology, and therapeutic options are discussed. [ABSTRACT FROM AUTHOR]

A control rate of approximately 80% has been obtained in 45 cases of juvenile nasopharyngeal angiofibroma treated by a single moderate dose of radiotherapy at the Princess Margaret Hospital, Toronto. The remaining patients ultimately achieved control, generally after further irradiation. Immediate side-effects of the treatment have been minimal, and no late complications have been observed. In 2-20 years' follow-up, no irradiation-induced tumors have been found. Superiority of irradiation in these cases over surgery is emphasized, as well as the importance of using sophisticated techniques to limit the volume of tissues irradiated and protect vulnerable radiosensitive structures. Because tumor regression can be expected to continue for many months after treatment has been completed, a policy of observation following radiotherapy is recommended. [ABSTRACT FROM AUTHOR]

Upper arm arteriovenous bridge grafts are often required after failure of more distal access grafts. A retrospective review was performed comparing 57 brachioaxillary bridge grafts fistulas (BAGF) with 79 brachiosubclavian bridge graft fistulas (BSGF) performed over a twelve-year period. There was no statistical difference in primary or secondary patency rates. There was a statically higher rate of infection in the BSGF group (p<05). while thrombosis was more com mon in the BAGF group (p<.05) [ABSTRACT FROM PUBLISHER]

A high-risk patient underwent exclusion of an abdominal aortic aneurysm with aortofemoral bypass. During the procedure a horseshoe kidney was found to be overlying the aorta. Postoperatively retrograde perfusion of the aneurysm via a recanalized right iliac artery occurred and led to doubling of the aneu rysm's size, necessitating reoperation. The operative approach and pertinent literature are reviewed. [ABSTRACT FROM PUBLISHER]

The authors report 2 cases of acute axillary artery thrombosis in children with blunt trauma. The incidence and etiology of this injury are discussed, par ticularly as they relate to injury of the great vessels in blunt chest trauma. Diagnostic and therapeutic approaches are outlined for this uncommon but po tentially disabling condition. [ABSTRACT FROM PUBLISHER]

Anastomotic false aneurysm is a commonly reported complication of bypass surgery, but blunt trauma has been a rare etiologic mechanism. An unusual case of a traumatic false aneurysm arising in the distal anastomosis of an in-situ femoro-popliteal bypass graft is presented and the pathophysiology of the entity is discussed. [ABSTRACT FROM PUBLISHER]

Upper arm arteriovenous bridge grafts are often required after failure of more distal access grafts. A retrospective review was performed comparing 57 brachioaxillary bridge grafts fistulas (BAGF) with 79 brachiosubclavian bridge graft fistulas (BSGF) performed over a twelve-year period. There was no statistical difference in primary or secondary patency rates. There was a statically higher rate of infection in the BSGF group (p<.05) while thrombosis was more common in the BAGF group (p<.05). [ABSTRACT FROM AUTHOR]

A high-risk patient underwent exclusion of an abdominal aortic aneurysm with aortofemoral bypass. During the procedure a horseshoe kidney was found to be overlying the aorta. Postoperatively retrograde perfusion of the aneurysm via a recanalized right iliac artery occurred and led to doubling of the aneurysm's size, necessitating reoperation. The operative approach and pertinent literature are reviewed. [ABSTRACT FROM AUTHOR]

The authors report 2 cases of acute axillary artery thrombosis in children with blunt trauma. The incidence and etiology of this injury are discussed, particularly as they relate to injury of the great vessels in blunt chest trauma. Diagnostic and therapeutic approaches are outlined for this uncommon but potentially disabling condition. [ABSTRACT FROM AUTHOR]

Anastomotic false aneurysm is a commonly reported complication of bypass surgery, but blunt trauma has been a rare etiologic mechanism. An unusual case of a traumatic false aneurysm arising in the distal anastomosis of an in-situ femoro-popliteal bypass graft is presented and the pathophysiology of the entity is discussed. [ABSTRACT FROM AUTHOR]

The routine or selective use of an intraarterial shunt during carotid endar terectomy (CEA) remains a controversial issue. Numerous investigators have proposed various shunting devices in an effort to minimize possible associated complications. The presented case illustrates an unusual complication that de veloped during a CEA, felt to be related to a malfunction of a Pruitt-Inahara (P I) shunt. [ABSTRACT FROM PUBLISHER]

The routine or selective use of an intraarterial shunt during carotid endarterectomy (CEA) remains a controversial issue. Numerous investigators have proposed various shunting devices in an effort to minimize possible associated complications. The presented case illustrates an unusual complication that developed during a CEA, felt to he related to a malfunction of a Pruitt-Inahara (P-I) shunt. [ABSTRACT FROM AUTHOR]