A Parametric Simulation of Neuronal Noise From Microelectrode Recordings.

In this paper we present an efficient model of microelectrode recordings (MER) from the subthalamic nucleus acquired during deep brain stimulation (DBS) surgery. The model shows how changes in the "noise" relate to the neuronal spike time statistics. A top-down approach is used with analysis-by-synthesis of the MER power spectra. The model is built around a sum of filtered point processes consisting of thousands of neurons and including extracellular filtering. The quality of the model is demonstrated through comparisons to recordings from eight individuals (both hemispheres in six) who have undergone DBS implantation for the treatment of Parkinson's disease. The simulated recordings were compared using their voltage amplitude distributions, power spectral density estimates and phase synchrony while varying only one free parameter (the shape of the inter-spike interval distribution). Through this simple model, we show that the noise present in a DBS MER contains properties that match that of patient recordings when a Weibull distribution with shape parameter of 0.8 is used for the inter-spike interval.

Report from the Society of Thoracic Surgeons National Database Workforce: clarifying the definition of operative mortality.

Several distinct definitions of postoperative death have been used in various quality reporting programs. Some have defined postoperative mortality as the occurrence of death after a surgical procedure when the patient dies while still in the hospital, while others have considered all deaths occurring within a predetermined, standardized time interval after surgery to be postoperative mortality. While mortality data are still collected and reported using both these individual definitions, the Society of Thoracic Surgeons (STS) believes that either approach alone may be inadequate. Accordingly, the STS prefers a more encompassing metric, Operative Mortality. Operative Mortality is defined in all STS databases as (1) all deaths, regardless of cause, occurring during the hospitalization in which the operation was performed, even if after 30 days (including patients transferred to other acute care facilities); and (2) all deaths, regardless of cause, occurring after discharge from the hospital, but before the end of the 30th postoperative day. This article provides clarification for some uncommon but important scenarios in which the correct application of this definition may be challenging.

Bis(trimethylphosphine)silver(I) hexafluorophosphate.

In the title two-coordinate silver compound, [Ag(C(3)H(9)P)(2)]PF(6), the cation has crystallographically imposed mirror symmetry, and approximates very closely to 3m (D(3d)) symmetry with fully staggered methyl groups in the solid state. The Ag atom has a nearly linear coordination geometry, with a P[bond]Ag[bond]P angle of 178.70 (4) degrees. The Ag[bond]P bond lengths are 2.3746 (12) and 2.3783 (12) A, which are significantly longer than the Au[bond]P bond length of 2.304 (1) A in the analogous two-coordinate gold cation. The lack of intramolecular steric effects within the present cations containing trimethylphosphine (cone angle 118 degrees), compared with those in known cations containing trimesitylphosphine (cone angle 212 degrees), provides a better comparison of M[bond]P distances and thus more conclusive evidence that Au really is smaller than Ag.

Multinuclear NMR Spectroscopic and X-ray Crystallographic Studies of a Series of Mercury(II) Complexes Containing the Bidentate Phosphine Ligand Ph(2)PCH(2)Si(CH(3))(2)CH(2)PPh(2) (L(2)).

The bidentate phosphine ligand Ph(2)PCH(2)Si(CH(3))(2)CH(2)PPh(2) (L(2)), an analogue of 1,3-bis(diphenylphosphino)propane (dppp), coordinates to mercury(II) salts to form complexes of the general formula [HgX(2).L(2)] (X = Cl, Br, I, NCS). Infrared, Raman, and multinuclear ((1)H, (13)C, (31)P, (199)Hg) NMR spectroscopic studies show that the complexes exhibit four-coordinate pseudotetrahedral metal geometry. [HgI(2)(Ph(2)PCH(2)Si(CH(3))(2)CH(2)PPh(2))] (1) crystallizes in the monoclinic space group P2(1)/n with a = 13.028(2) Å, b = 17.402(5) Å, c = 13.849(2) Å, beta = 90.635(14) degrees, V = 3139.5(11) Å(3), and Z = 4. The structure contains a tetrahedral mercury center with the phosphine ligand bound in a bidentate fashion: Hg-P 2.511(2), 2.515(2) Å; P-Hg-P 105.28(6) degrees. The complex [HgCl(2)](2).L(2) has also been generated via a 2:1 metal:phosphine stoichiometry.