Diffraction-contrast imaging of cold atoms

We consider the inverse problem of in-line holography, applied to minimally-destructive imaging of cold atom clouds. Absorption imaging near-resonance provides a simple, but destructive measurement of atom column density. Imaging off resonance greatly reduces heating, and sequential images may be taken. Under the conditions required for off-resonant imaging, the generally-intractable inverse problem may be linearized. A minimally-destructive, quantitative and high-resolution image of the atom cloud column density is then retrieved from a single diffraction pattern.Comment: 4 pages, 3 figures v2: minor changes in response to referee reports, mostly additional experimental detail v3: revisions to figure 3: added trace and changed image. Minor text and referencing changes. Accepted by Phys Rev A (Rapid Commun

Professionalism in residency training: A compilation of desirable behaviors and a case-based comparison between pathologists in training and practice

Professionalism is one of the most important competencies for physicians but is also the most difficult to teach, assess, and manage. To better understand professionalism in pathology, we surveyed practicing pathologists and pathology residents and fellows in training. We identified 12 key desirable attributes of professionalism. In addition, 8 case scenarios highlighting unprofessional behavior were presented, and results between pathologists in practice and in training were compared. No significant differences between attending pathologists and residents were identified in how these cases should be managed. Our study demonstrated remarkable concordance between practicing pathologists and residents as to what constitutes professionalism and how to manage unprofessional behavior. Our case-based approach can be a useful technique to teach professionalism to both pathologists in practice and in training

Plasma Physics

Contains reports on two research projects.United States Atomic Energy Commission (Contract AT(30-1)-1842

Plasma Physics

Contains reports on three research projects.U. S. Atomic Energy Commission (Contract AT(30- 1)- 1842

Atomic quasi-Bragg diffraction in a magnetic field

We report on a new technique to split an atomic beam coherently with an easily adjustable splitting angle. In our experiment metastable helium atoms in the |{1s2s}^3S_1 M=1> state diffract from a polarization gradient light field formed by counterpropagating \sigma^+ and \sigma^- polarized laser beams in the presence of a homogeneous magnetic field. In the near-adiabatic regime, energy conservation allows the resonant exchange between magnetic energy and kinetic energy. As a consequence, symmetric diffraction of |M=0> or |M=-1> atoms in a single order is achieved, where the order can be chosen freely by tuning the magnetic field. We present experimental results up to 6th order diffraction (24 \hbar k momentum splitting, i.e., 2.21 m/s in transverse velocity) and present a simple theoretical model that stresses the similarity with conventional Bragg scattering. The resulting device constitutes a flexible, adjustable, large-angle, three-way coherent atomic beam splitter with many potential applications in atom optics and atom interferometry.Comment: 4 pages, 5 figure

The Continuing Fellowship Conundrum

The debate for a fair, equitable, and reasonable pathology fellowship application and selection process has been an ongoing issue with ebb and flow over approximately the past 10 years. The authors of this commentary have been closely involved with the fellowship issue over the past decade and have been part of the effort to achieve a workable solution with widespread support. Possible solutions to the concerns raised by various parties have included efforts to implement a uniform timeline, a formal match through the National Resident Match- ing Program (NRMP), a formal match through the San Fran- cisco Matching Program, and most recently (and the focus of this commentary) a Code of Conduct (Honor Code) and appli- cation clearing house overseen by the Association of Pathology Chairs (APC). Table 1 summarizes these efforts and their out- comes to date

La5 Ti2 Cu0.9 Ag0.1 S5 O7 Modified with a Molecular Ni Catalyst for Photoelectrochemical H2 Generation.

The stable and efficient integration of molecular catalysts into p-type semiconductor materials is a contemporary challenge in photoelectrochemical fuel synthesis. Here, we report the combination of a phosphonated molecular Ni catalyst with a TiO2 -coated La5 Ti2 Cu0.9 Ag0.1 S5 O7 photocathode for visible light driven H2 production. This hybrid assembly provides a positive onset potential, large photocurrents, and high Faradaic yield for more than three hours. A decisive feature of the hybrid electrode is the TiO2 interlayer, which stabilizes the oxysulfide semiconductor and allows for robust attachment of the phosphonated molecular catalyst. This demonstration of an oxysulfide-molecular catalyst photocathode provides a novel platform for integrating molecular catalysts into photocathodes and the large photovoltage of the presented system makes it ideal for pairing with photoanodes.Japan Society for the Promotion of Science (JSPS); Christian Doppler Research Association (Austrian Federal Ministry of Science, Research and Economy and the National Foundation for Research, Technology and Development); OMV group; EPSRC, Grants-in-Aids for Scientific Research and for Young Scientists from JSP

A Novel Assay to Trace Proliferation History In Vivo Reveals that Enhanced Divisional Kinetics Accompany Loss of Hematopoietic Stem Cell Self-Renewal

BACKGROUND: The maintenance of lifelong blood cell production ultimately rests on rare hematopoietic stem cells (HSCs) that reside in the bone marrow microenvironment. HSCs are traditionally viewed as mitotically quiescent relative to their committed progeny. However, traditional techniques for assessing proliferation activity in vivo, such as measurement of BrdU uptake, are incompatible with preservation of cellular viability. Previous studies of HSC proliferation kinetics in vivo have therefore precluded direct functional evaluation of multi-potency and self-renewal, the hallmark properties of HSCs. METHODOLOGY/PRINCIPAL FINDINGS: We developed a non-invasive labeling technique that allowed us to identify and isolate candidate HSCs and early hematopoietic progenitor cells based on their differential in vivo proliferation kinetics. Such cells were functionally evaluated for their abilities to multi-lineage reconstitute myeloablated hosts. CONCLUSIONS: Although at least a few HSC divisions per se did not influence HSC function, enhanced kinetics of divisional activity in steady state preceded the phenotypic changes that accompanied loss of HSC self-renewal. Therefore, mitotic quiescence of HSCs, relative to their committed progeny, is key to maintain the unique functional and molecular properties of HSCs