Village Voice Essay

Zombies. Impossible Burgers. Campus Politic

A Recently Discovered Letter to a Loved One

A short letter to a loved one written from by someone in battle against an intractible and eternal enemy

The cerebrospinal fluid protein

Thesis (M.D.)--Boston Universit

Compression of multispectral Landsat imagery using the Embedded Zerotree Wavelet (EZW) algorithm

The Embedded Zerotree Wavelet (EZW) algorithm has proven to be an extremely efficient and flexible compression algorithm for low bit rate image coding. The embedding algorithm attempts to order the bits in the bit stream in numerical importance and thus a given code contains all lower rate encodings of the same algorithm. Therefore, precise bit rate control is achievable and a target rate or distortion metric can be met exactly. Furthermore, the technique is fully image adaptive. An algorithm for multispectral image compression which combines the spectral redundancy removal properties of the image-dependent Karhunen-Loeve Transform (KLT) with the efficiency, controllability, and adaptivity of the embedded zerotree wavelet algorithm is presented. Results are shown which illustrate the advantage of jointly encoding spectral components using the KLT and EZW

Focused ultrasound excites neurons via mechanosensitive calcium accumulation and ion channel amplification

Ultrasonic neuromodulation has the unique potential to provide non-invasive control of neural activity in deep brain regions with high spatial precision and without chemical or genetic modification. However, the biomolecular and cellular mechanisms by which focused ultrasound excites mammalian neurons have remained unclear, posing significant challenges for the use of this technology in research and potential clinical applications. Here, we show that focused ultrasound excites neurons through a primarily mechanical mechanism mediated by specific calcium-selective mechanosensitive ion channels. The activation of these channels results in a gradual build-up of calcium, which is amplified by calcium- and voltage-gated channels, generating a burst firing response. Cavitation, temperature changes, large-scale deformation, and synaptic transmission are not required for this excitation to occur. Pharmacological and genetic inhibition of specific ion channels leads to reduced responses to ultrasound, while over-expressing these channels results in stronger ultrasonic stimulation. These findings provide a critical missing explanation for the effect of ultrasound on neurons and facilitate the further development of ultrasonic neuromodulation and sonogenetics as unique tools for neuroscience research

807-2 Effect of Age on Left Ventricular Diastolic Filling Patterns During Orthostatic Stress

Although numerous studies have demonstrated reduced early diastolic left ventricular (LV) peak filling velocity IE) and accentuated late filling velocity (A) with advancing age in the supine position, the effect of orthostatic stress on age-associated diastolic filling patterns is unknown. Accordingly, 30 healthy normotensive volunteers ages 19 to 90 years from the Baltimore Longitudinal Study of Aging underwent sequential Doppler echocardiography after 3 minutes each in the supine, seated, and standing positions. In the overall sample, standing was accompanied by an increase in heart rate (HR) of 8.8±1.7 beats/min, and decreases in E(20.6±2.7cm/sl. A 150±2.7cm/s)and LV diastolic dimension (LVDD) (7.8±0.8mm), x±SEM, each p<0.001 versus supine values. Systolic blood pressure (SBP) and atrial filling fraction (AFF) were unaffected by posture. Correlation coefficients versus age for relevant Doppler and hemodynamic variables are shown.EAE/AAFFHRSBPLVDDSupine-0.58†0.80†-0.78†0.84†0.010.56†-0.14Sit-0.360.77†-0.83†0.78†-0.040.37*-0.07Stand-0.240.60†-0.69†0.71†-0.320.47†0.09ΔSupine → Stand0.53†-0.46†0.56†-0.17-0.61†0.220.40**p<005†p<001Thus, orthostatic stress abolishes the reduction of E and attenuates the exaggerated A observed with advancing age in the supine position. probably because of the blunted standing-induced HR increase in older subjects. However, the supine age-associated increase in AFF is unaffected by orthostasis

Precise Measurement of the Spin Parameter of the Stellar-Mass Black Hole M33 X-7

In prior work, {\it Chandra} and Gemini-North observations of the eclipsing X-ray binary M33 X-7 have yielded measurements of the mass of its black hole primary and the system's orbital inclination angle of unprecedented accuracy. Likewise, the distance to the binary is known to a few percent. In an analysis based on these precise results, fifteen {\it Chandra} and {\it XMM-Newton} X-ray spectra, and our fully relativistic accretion disk model, we find that the dimensionless spin parameter of the black hole primary is $a_* = 0.77 \pm 0.05$. The quoted 1-$\sigma$ error includes all sources of observational uncertainty. Four {\it Chandra} spectra of the highest quality, which were obtained over a span of several years, all lead to the same estimate of spin to within statistical errors (2%), and this estimate is confirmed by 11 spectra of lower quality. There are two remaining uncertainties: (1) the validity of the relativistic model used to analyze the observations, which is being addressed in ongoing theoretical work; and (2) our assumption that the black hole spin is approximately aligned with the angular momentum vector of the binary, which can be addressed by a future X-ray polarimetry mission.Comment: 14 pages, 3 figures, 1 table, published in ApJ Letters; as explained in the erratum at the end of the text, the spin parameter has been corrected upward from a*=0.77 to a*=0.84. Apart from the addition of the erratum, the paper is unchanged

BUMC Annual Report

Annual report of the Boston University Medical Center