Acoustic scattering by near-surface inhomogeneities in porous media.

A theoretical and experimental investigation into the influence of nearsurface ihhomogeneities on the reflection of air-borne acoustic fields at a porous ground surface is conducted. Two theoretical approaches to the three-dimensional physical problem are presented, both being initially formulated as boundary value problems but with subsequent reformulation as boundary integral equations via Green’s Second Theorem. In the first near-surface inhomogeneity approach, a rigid inhomogeneity is embedded within the porous medium and the boundary value problem is formulated by assuming continuity of pressure and normal velocity at the ground surface, Sommerfeld’s radiation conditions, and the Neumann boundary condition on the surface of the inhomogeneity. In the second surface inhomogeneity approach, the boundary value problem is formulated by assuming an impedance boundary condition on the plane boundary. Any near-surface inhomogeneities are assumed to induce a local variation of surface impedance within the boundary, and analytical expressions for such induced variations in surface impedance are presented. The resultant integral equations require knowledge of the Green’s function for acoustic propagation in the presence of a plane boundary but in the absence of the inhomogeneity, and methods for calculating these Green’s functions are discussed. The numerical solution of the boundary integral equations by a simple , boundary element method is described. The solution, which reduces to a system of linear equations with a block circulant coefficient matrix, is applicable to any inhomogeneity which is axisymmetric about a vertical axis; and for the near-surface inhomogeneity approach, the inhomogeneity must also be smooth. The numerical solutions have shown good agreement with classical results. The experimental measurements, presented in the form of spectra of the difference in sound pressure levels received at vertically separated points above surfaces of different media containing various scatterers, are in good agreement with the theoretical predictions

Puzzling subunits of mitochondrial cytochrome reductase

The ubiquinol-cytochrome c reductase complex, like the other proton-pumping respiratory complexes of mitochondria, is an assembly of many different subunits. However, only a few of these subunits participate directly in the electron transfer and proton translocation. The roles of the other subunits are largely unknown. We discuss here some intriguing features of two of these subunits

Brief for Respondents. County of Los Angeles v. Mendez, 137 S.Ct. 1539 (2017) (No. 16-3690), 2017 WL 696103

QUESTIONS PRESENTED 1. Does the legal framework set out in Grnham v. Connor, 490 U.S. 386 (1989), apply to actions by police that foreseeably create a need for the use of force? 2. In an action under 42 U.S.C. § 1983, where a house search that violates the Fourth Amendment results in the shooting of an innocent resident who did not know that the intruders were sheriff’s deputies, does a resident’s nonculpable response to the intrusion constitute a superseding cause that bars relief for the residents’ injur

Role of Kindness in Cancer Care

The wonders of high-tech cancer care are best complemented by the humanity of high-touch care. Simple kindnesses can help to diffuse negative emotions that are associated with cancer diagnosis and treatment-and may even help to improve patients\u27 outcomes. On the basis of our experience in cancer care and research, we propose six types of kindness in cancer care: deep listening , whereby clinicians take the time to truly understand the needs and concerns of patients and their families; empathy for the patient with cancer, expressed by both individual clinicians and the care culture, that seeks to prevent avoidable suffering; generous acts of discretionary effort that go beyond what patients and families expect from a care team; timely care that is delivered by using a variety of tools and systems that reduce stress and anxiety; gentle honesty, whereby the truth is conveyed directly in well-chosen, guiding words; and support for family caregivers, whose physical and mental well-being are vital components of the care their loved ones receive. These mutually reinforcing manifestations of kindness-exhibited by self-aware clinicians who understand that how care is delivered matters-constitute a powerful and practical way to temper the emotional turmoil of cancer for patients, their families, and clinicians themselves

Research Note: More on improving service quality measurement

In this note we respond to Brown, Churchill, and Peter's (1993) critique of SERVQUAL's difference-score conceptualization. We demonstrate that the claimed psychometric superiority of the alternative non-difference score conceptualization is debatable. We also argue that the SERVQUAL conceptualization offers richer diagnostics

Alternative scales for measuring service quality: A comparative assessment based on psychometric and diagnostic criteria

Service quality measurement is an area of growing interest to researchers and managers. It is also an area characterized by debate concerning the need for measuring customer expectations and how they should be measured. Building on a synthesis of the extant literature on customer expectations and service quality measurement, this article identifies unresolved issues and develops three alternative questionnaire formats to address them. It then discusses an empirical study that evaluated the three formats in four different sectors. The article concludes with practical implications and directions for further research stemming from the study's findings