Numerical study of the thermoelectric power factor in ultra-thin Si nanowires

Low dimensional structures have demonstrated improved thermoelectric (TE) performance because of a drastic reduction in their thermal conductivity, {\kappa}l. This has been observed for a variety of materials, even for traditionally poor thermoelectrics such as silicon. Other than the reduction in {\kappa}l, further improvements in the TE figure of merit ZT could potentially originate from the thermoelectric power factor. In this work, we couple the ballistic (Landauer) and diffusive linearized Boltzmann electron transport theory to the atomistic sp3d5s*-spin-orbit-coupled tight-binding (TB) electronic structure model. We calculate the room temperature electrical conductivity, Seebeck coefficient, and power factor of narrow 1D Si nanowires (NWs). We describe the numerical formulation of coupling TB to those transport formalisms, the approximations involved, and explain the differences in the conclusions obtained from each model. We investigate the effects of cross section size, transport orientation and confinement orientation, and the influence of the different scattering mechanisms. We show that such methodology can provide robust results for structures including thousands of atoms in the simulation domain and extending to length scales beyond 10nm, and point towards insightful design directions using the length scale and geometry as a design degree of freedom. We find that the effect of low dimensionality on the thermoelectric power factor of Si NWs can be observed at diameters below ~7nm, and that quantum confinement and different transport orientations offer the possibility for power factor optimization.Comment: 42 pages, 14 figures; Journal of Computational Electronics, 201

Professionalism, Golf Coaching and a Master of Science Degree: A commentary

As a point of reference I congratulate Simon Jenkins on tackling the issue of professionalism in coaching. As he points out coaching is not a profession, but this does not mean that coaching would not benefit from going through a professionalization process. As things stand I find that the stimulus article unpacks some critically important issues of professionalism, broadly within the context of golf coaching. However, I am not sure enough is made of understanding what professional (golf) coaching actually is nor how the development of a professional golf coach can be facilitated by a Master of Science Degree (M.Sc.). I will focus my commentary on these two issues

Shop stewards’ leadership, left-wing activism and collective workplace union organisation

Providing an account of the dynamic interrelationship between shop steward leadership and membership interaction, Ralph Darlington focuses particular attention on the much-neglected crucial role that left-wing political activists can play in shaping the nature of collective workplace relations

Unmasked testicular seminoma during use of hormonal transgender woman therapy: A hidden hCG-Secreting tumor

Management of gender-affirming hormone therapy (HT) in transgender women includes surveillance of testosterone (T) levels. Failure of T to suppress, despite adherence to therapy, warrants additional investigations for unexpected sources of T or factors stimulating T secretion. Possible causes include T or gonadotropin production by an occult neoplasm. Testicular cancer is the most common malignancy affecting biological men aged between 15 and 35 years. Patients may be asymptomatic until tumor burden is high and/or metastatic. Hormone-producing tumors have rarely been reported in treated transgender women. Routine screening tests are recommended in a gender-incongruent person as per the 2017 Endocrine Society guidelines with measurement of T levels every 3 months initially to reach a goal of less than 50 ng/dL. Expectations should be discussed in detail with the transgender person since anticipated physical changes may not be notable for 6 to 18 months. We herein describe a case of a transgender woman who underwent standard HT including gonadotropin suppression with a gonadotropin-releasing hormone agonist, whose total T level failed to suppress. Testing revealed an elevated serum level of the beta subunit of human chorionic gonadotropin (β‐hCG), diagnostic of an hCG-secreting testicular seminoma, as the underlying cause of unexpected T production. This case illustrates how easily a testicular cancer can remain unnoticed because it can be asymptomatic and the necessity to be alert to, and act on, anomalous laboratory results during treatment of a transgender person. © Published by Oxford University Press on behalf of the Endocrine Society 2020. This work is written by (a) US Government employee(s) and is in the public domain in the US. This Open Access article contains public sector information licensed under the Open Government Licence v2.0 (http://www.nationalarchives.gov.uk/doc/open-government-licence/version/2/).Open access journalThis item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]

GRAS 28 flavoring substances

The 28th publication by the Expert Panel of the Flavor and Extract Manufacturers Association provides an update on recent progress in the consideration of flavoring ingredients generally recognized as safe under the Food Additives Amendment

GRAS 29 flavoring substances

The 29th publication by the Expert Panel of the Flavor and Extract Manufacturers Association provides an update on recent progress in the consideration of flavoring ingredients generally recognized as safe under the Food Additives Amendment

GRAS 29 flavoring substances

The 29th publication by the Expert Panel of the Flavor and Extract Manufacturers Association provides an update on recent progress in the consideration of flavoring ingredients generally recognized as safe under the Food Additives Amendment