Neutron diffraction study of lunar materials Final report

Apollo 12 lunar samples studied with neutron diffraction at room and cryogenic temperature

Graduate Recital, Violin

My M.M. thesis presents a diversity of violin literature from Bach to the present time. The pieces I chose feature the violin in different settings: unaccompanied solo, sonata with piano, concerto with orchestra, and showpieces accompanied by piano. The contrast of the light refined styles of Bach and Mozart compliment the flashier show works of Bloch and Kreisler, while the David Stock Chameleon for solo violin represents the other end of the spectrum and the latest in violin literature. The Mozart Concerto in A Major will be performed with a chamber orchestra. This is a unique opportunity, and it is not done very often in solo recitals

A parameterization of Greenland's tip jets suitable for ocean or coupled climate models

Greenland's tip jets are low-level, high wind speed jets forced by an interaction of the synoptic-scale atmospheric flow and the steep, high orography of Greenland. These jets are thought to play an important role in both preconditioning for, and triggering of, open-ocean convection in the Irminger Sea. However, the relatively small spatial scale of the jets prevents their accurate representation in the relatively low resolution (~1 degree) atmospheric (re-)analyses which are typically used to force ocean general circulation models (e.g. ECMWF ERA-40 and NCEP reanalyses, or products based on these). Here we present a method of ‘bogussing’ Greenland's tip jets into such surface wind fields and thus, via bulk flux formulae, into the air-sea turbulent flux fields. In this way the full impact of these mesoscale tip jets can be incorporated in any ocean general circulation model of sufficient resolution. The tip jet parameterization is relatively simple, making use of observed linear gradients in wind speed along and across the jet, but is shown to be accurate to a few m s-1 on average. The inclusion of tip jets results in a large local increase in both the heat and momentum fluxes. When applied to a 1-dimensional mixed-layer model this results in a deepening of the winter mixed-layer of over 300 m. The parameterization scheme only requires 10 meter wind speed and mean sea level pressure as input fields; thus it is also suitable for incorporation into a coupled atmosphere-ocean climate model at the coupling stage

How does Labrador Sea Water enter the deep western boundary current?

Author Posting. © American Meteorological Society, 2008. This article is posted here by permission of American Meteorological Society for personal use, not for redistribution. The definitive version was published in Journal of Physical Oceanography 38 (2008): 968-983, doi:10.1175/2007JPO3807.1.Labrador Sea Water (LSW), a dense water mass formed by convection in the subpolar North Atlantic, is an important constituent of the meridional overturning circulation. Understanding how the water mass enters the deep western boundary current (DWBC), one of the primary pathways by which it exits the subpolar gyre, can shed light on the continuity between climate conditions in the formation region and their downstream signal. Using the trajectories of (profiling) autonomous Lagrangian circulation explorer [(P)ALACE] floats, operating between 1996 and 2002, three processes are evaluated for their role in the entry of Labrador Sea Water in the DWBC: 1) LSW is formed directly in the DWBC, 2) eddies flux LSW laterally from the interior Labrador Sea to the DWBC, and 3) a horizontally divergent mean flow advects LSW from the interior to the DWBC. A comparison of the heat flux associated with each of these three mechanisms suggests that all three contribute to the transformation of the boundary current as it transits the Labrador Sea. The formation of LSW directly in the DWBC and the eddy heat flux between the interior Labrador Sea and the DWBC may play leading roles in setting the interannual variability of the exported water mass.We are also grateful to the NSF for their support of this research

Is Minoxidil Efficacious and Safe for the Treatment of Androgenetic Alopecia (AGA) in Men, and If So, What Is the Optimal Strength and Means of Delivery?

OBJECTIVE: The objective of this selective EBM review is to determine whether or not minoxidil is efficacious and safe for the treatment of androgenetic alopecia (AGA) in men, and if so, what is the optimal strength and means of delivery. STUDY DESIGN: Review of three double-blind randomized controlled trials studying men (18-49 y/o) with androgenetic alopecia published in English from 2007-2009. DATA SOURCES: Three articles of double-blind randomized controlled trials found via PubMed. OUTCOMES MEASURED: Outcomes measured included the efficacy and safety of minoxidil as well as the optimal strength and means of delivery of the drug. For efficacy, parameters used included target area hair count (TAHC), subject assessment using rating scale, expert panel or investigator assessment via photographic review and then rated on the same scale used by subjects. To assess safety, the studies used subject report of symptoms of scalp irritation, investigator examination of signs of scalp irritation, and change in vital signs and/or abnormal lab values for systemic effects. As for the optimal strength and means of delivery, this was evaluated based on the way each study was designed. In the Olsen study, 5% minoxidil foam applied twice daily was compared to a placebo, while the Tsuboi study compared application of 5% minoxidil lotion to 1% minoxidil lotion with both also applied twice daily, and the Shin study compared the use of a placebo in the morning and 5% minoxidil/0.01% tretinoin in the evening against twice daily application of 5% minoxidil alone. RESULTS: The Olsen and Tsuboi studies demonstrated that 5% minoxidil applied twice daily was efficacious without significant adverse effects when compared to placebo or 1% minoxidil respectively, and the Shin study raised the possibility of combined 5% minoxidil/0.01% tretinoin to obtain similar efficacy without significant adverse effects with only once daily usage. CONCLUSION: Minoxidil is safe and efficacious in the treatment of male AGA especially at the strength of 5% in either foam or solution preparation for twice daily use

The entrainment and homogenization of tracers within the cyclonic gulf stream recirculation gyre

Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution January 1987The various distributions of tracer associated with the Northern Recirculation Gyre of the Gulf Stream (NRG) are studied to try to obtain information about the flow. An advective-diffusive numerical model is implemented to aid in the investigation. The model is composed of a gyre adjacent to a boundary current in which a source of tracer is specified at the upstream edge of the current. This set up attempts to simulate the lateral transfer of properties from the Deep Western Boundary Current (DWBC) to the NRG in the region where the two flows are in close contact west of the Grand Banks. The results of the model are analyzed in some detail. Tracer is entrained into the gyre as a plume which extends from the boundary current and spirals across streamlines toward the gyre center. The maintenance of the spiral during spin-up and its relationship to the occurrence of homogenization at steady state is examined. An asymmetry in the spiral exists due to the ellipticity of the gyre, which also effects homogenization. The anomalous properties that are fluxed into the NRG include salt, oxygen, and freon. These particular tracers are independent from each other, the former two because they are characterized by different vertical profiles in the deep layer. This results in a decay of oxygen but not salt, due to the presence of vertical mixing as discussed by Hogg et al. (1986, Deep-Sea Research, 33, 1139-1165). Their analysis is expanded upon here. The effect of vertical mixing on the gyre/boundary current system is examined within the context of the numerical model. Results are applied to recently collected water sample data from the region which leads to an estimate of the lateral and vertical eddy diffusion coefficients and an estimate of the amount of oxygen in the NRG that has diffused from the DWBC. The accumulation of freon within the NRG is considered in addition to salt and oxygen. Appreciable levels of freon have been present in the ocean only since 1950, and the atmospheric source functions have been increasing steadily since then. A simple overflow model is presented of the manner in which freon may be stirred in the Norwegian-Greenland basin prior to overflowing and entering the DWBC. Once in the boundary current the concentrations are diluted by way of mixing with surrounding water. Two different schemes are considered in which the immediate surrounding water accumulates a substantial amount of freon as time progresses. These models suggest that the freon-11:freon-12 ratio may not be a conserved quantity for the water in the core of the DWBC. It is found that the level of freon in the NRG is barely above the existing background level.This work was supported by the office of Naval Research through contracts N00014-76-C-0197 and N00014-84-C-0134, NR 083-400; and N00014-82-C-0019 and N00014-85-C-0001, NR 083-004, and the National Science Foundation through grant 0CE82-14925

Shelfbreak circulation in the Alaskan Beaufort Sea : mean structure and variability

Author Posting. © American Geophysical Union, 2004. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research 109 (2004): C04024, doi:10.1029/2003JC001912.Historical hydrographic and current meter data are used to investigate the properties and circulation at the shelf edge of the Alaskan Beaufort Sea. Thirty-three individual cross-sections, spanning the time period 1950 to 1987, are combined in a topographical framework to produce mean vertical hydrographic sections, as well as a section of mean absolute geostrophic velocity referenced using the current meter data. This reveals the presence of a narrow (order 20 km) eastward current, referred to as the Beaufort shelfbreak jet. The jet has three distinct seasonal configurations: In late-spring to late-summer, cold, winter-transformed Bering water is advected in a subsurface current; from mid-summer to early fall a surface intensified current advects predominantly Bering summer water; and from mid-fall to mid-spring, under easterly winds, the jet transports upwelled Atlantic water. The volume transport of the jet represents a significant fraction of the inflowing transport through Bering Strait. While the characteristics and flow of the winter-transformed Bering water vary interannually, this water mass ventilates predominantly the upper halocline.This work was supported by the Office of Naval Research under contract N00014-98- 1-0046

Seasonal variation of upwelling in the Alaskan Beaufort Sea : impact of sea ice cover

Author Posting. © American Geophysical Union, 2012. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research 117 (2012): C06022, doi:10.1029/2012JC007985.Data from a mooring array deployed from August 2002 to September 2004 are used to characterize differences in upwelling near the shelf break in the Alaskan Beaufort Sea due to varying sea ice conditions. The record is divided into three ice seasons: open water, partial ice, and full ice. The basic response is the same in each of the seasons. Roughly 8 h after the onset of easterly winds the shelf break jet reverses, followed approximately 10 h later by upwelling of saltier water which is cold near the shelf break (Pacific Winter Water) and warm at depth (Atlantic Water). The secondary circulation at the outer shelf is, to first order, consistent with a two-dimensional Ekman balance of offshore flow in the upper layer and onshore flow at depth. There are, however, important seasonal differences in the upwelling. Overall the response is strongest in the partial ice season and weakest in the full ice season. It is believed that these differences are dictated by the degree to which wind stress is transmitted through the pack-ice, as the strength of the wind-forcing was comparable over the three seasons. An EOF-based upwelling index is constructed using information about the primary flow, secondary flow, and hydrography. The ability to predict upwelling using the wind record alone is explored, which demonstrates that 90% of easterly wind events exceeding 9.5 m s−1 drive significant upwelling. During certain periods the ice cover on the shelf became landfast, which altered the upwelling and circulation patterns near the shelf break.The following grants provided support for this study: National Ocean Partnership Program project N00014-07-1-1040 and National Science Foundation projects OPP-0731928 and OPP-0713250.2012-12-2

Aircraft-based observations of air-sea fluxes over Denmark Strait and the Irminger sea during high wind speed conditions

The impact of targeted sonde observations on the 1-3 day forecasts for northern Europe is evaluated using the Met Office four-dimensional variational data assimilation scheme and a 24 km gridlength limited-area version of the Unified Model (MetUM). The targeted observations were carried out during February and March 2007 as part of the Greenland Flow Distortion Experiment, using a research aircraft based in Iceland. Sensitive area predictions using either total energy singular vectors or an ensemble transform Kalman filter were used to predict where additional observations should be made to reduce errors in the initial conditions of forecasts for northern Europe. Targeted sonde data was assimilated operationally into the MetUM. Hindcasts show that the impact of the sondes was mixed. Only two out of the five cases showed clear forecast improvement; the maximum forecast improvement seen over the verifying region was approximately 5% of the forecast error 24 hours into the forecast. These two cases are presented in more detail: in the first the improvement propagates into the verification region with a developing polar low; and in the second the improvement is associated with an upper-level trough. The impact of cycling targeted data in the background of the forecast (including the memory of previous targeted observations) is investigated. This is shown to cause a greater forecast impact, but does not necessarily lead to a greater forecast improvement. Finally, the robustness of the results is assessed using a small ensemble of forecasts