Nerve localization techniques for peripheral nerve block and possible future directions

Ultrasound guidance is now a standard nerve localization technique for peripheral nerve block (PNB). Ultrasonography allows simultaneous visualization of the target nerve, needle, local anesthetic injectate and surrounding anatomical structures. Accurate deposition of local anesthetic next to the nerve is essential to the success of the nerve block procedure. Unfortunately, due to limitations in the visibility of both needle tip and nerve surface, the precise relationship between needle tip and target nerve is unknown at the moment of injection. Importantly, nerve injury may result both from an inappropriately placed needle tip and inappropriately placed local anesthetic. The relationship between the block needle tip and target nerve is of paramount importance to the safe conduct of peripheral nerve block. This review summarizes the evolution of nerve localization in regional anesthesia, characterizes a problem faced by clinicians in performing ultrasound guided nerve block and explores the potential technological solutions to this problem

The Crisis of Cooperation: A Critical Analysis of Russian-Iranian Relations in the Post-Soviet Era

In the study of contemporary politics few interstate relationships have proven more instrumental, controversial, and perplexing to global policy makers than that which has persisted between Moscow and Tehran since the collapse of the USSR. Despite the great importance of Russian-Iranian relations to questions of global and regional politics there has, to date, been very little in the way of critical scholarship performed on the subject. While a wide-array of accounts from subject analysts provide a wealth of data on contemporary and historical events which have presumably defined and conditioned bilateral relations, there has been relatively little effort to isolate, examine, test, and evaluate those conditions or variables that are deemed salient to cooperation. In light of these circumstances, this study seeks to initiate a tradition of scholarship on Russian-Iranian relations that appeals broadly to the use of a scientific methodology. The first step of any scientific inquiry requires attention devoted expressly to the development of a dependent variable of bilateral political affinity. While it remains outside the scope of this present investigation to analyze the host of factors/conditions capable of influencing bilateral relations, the formalization of a variable which records changing political affinity is a necessary first step and one that will fill-in a significant gap within the existing literary tradition. Rather than simply dismissing the extant tradition of literature on Russian-Iranian relations, this study seeks to aggregate and transform the subject\u27s many diverse narratives into a user-friendly, quantitative, political metric which can form the basis for future empirical inquiry. Thus this study introduces a new approach to monitoring and measuring changes in Russian-Iranian cooperation known as General Political Affinity (GPA). Represented on the basis of a 21-point scaled indicator of bilateral affinity, GPA succinctly defines cooperation between Moscow and Tehran as the summation of three underlying, persistent issue dimensions: the trade in conventional weapons; cooperation in Iranian nuclear development; and level of agreement on matters of Caspian Sea delimitation. In more generic terms, these three criteria seek to evaluate interstate cooperation, generically, as a product of: defense cooperation; state-sponsored development assistance; and territorial agreement. The unique approach to operationalizing political affinity presented in this study not only functionally improves our ability to explain and predict the course of Russian-Iranian relations, but also provides a new schematic for evaluating bilateral relations among all political dyads

Advances in Swept-Wavelength Interferometry for Precision Measurements

Originally developed for radar applications in the 1950s, swept-wavelength interferometry (SWI) at optical wavelengths has been an active area of research for the past thirty years, with applications in fields ranging from fiber optic telecommunications to biomedical imaging. It now forms the basis of several measurement techniques, including optical frequency domain reflectometry (OFDR), swept-source optical coherence tomography (SS-OCT), and frequency-modulated continuous-wave (FMCW) lidar. In this thesis, I present several novel contributions to the field of SWI that include improvements and extensions to the state of the art in SWI for performing precision measurements. The first is a method for accurately monitoring the instantaneous frequency of the tunable source to accommodate nonlinearities in the source tuning characteristics. This work extends the commonly used method incorporating an auxiliary interferometer to the increasingly relevant cases of long interferometer path mismatches and high-speed wavelength tuning. The second contribution enables precision absolute range measurements to within a small fraction of the transform-limited range resolution of the SWI system. This is accomplished through the use of digital filtering in the time domain and phase slope estimation in the frequency domain. Measurements of optical group delay with attosecond-level precision are experimentally demonstrated and applied to measurements of group refractive index and physical thickness. The accuracy of the group refractive index measurement is shown to be on the order of 10-6, while measurements of absolute thicknesses of macroscopic samples are accomplished with accuracy on the order of 10 nm. Furthermore, subnanometer uncertainty for relative thickness measurements can be achieved. For the case of crystalline silicon wafers, the achievable uncertainty is on the same order as the Si-Si bond length, opening the door to potential thickness profiling with single atomic monolayer precision. Thirdly, I demonstrate a novel implementation of SWI in the form of an SS-OCT system for performing quantitative measurements of spatially resolved refractive index contrast. This system relies on the depth-sectioning capability of SWI to isolate Fresnel reflectivity variations at an interface of interest within an optical sample. A motivating application for this quantitative index contrast measurement, volume lithography of photosensitive polymers, is also discussed in detail. This discussion includes the first demonstration of two-dimensional optical waveguide arrays fabricated in photosensitive polymers by means of holographic lithography

Isolated bladder metastasis causing large bowel obstruction: a case report of an atypical presentation of intussusception

Intussusception of the large bowel is a rare clinical entity. In adults, this pathology is usually associated with a malignant lead point and often requires operative management. Reported is the case of an 83-year-old female who was recently diagnosed with superficial bladder cancer (T1) treated by partial cystectomy. She presented 3 months post-operatively with an isolated mucosal metastasis of the transverse colon causing intussusception and large bowel obstruction. The patient was successfully treated by colonic resection with primary anastomosis. Histology was significant for a pedunculated sarcomatoid bladder carcinoma originating from the colonic mucosa with incomplete invasion of the bowel wall. An isolated mucosal metastasis of this variety has not been reported in the literature to date

The mechanism of inhibition of Ran-dependent nuclear transport by cellular ATP depletion

Rran-dependent nuclear transport requires a nuclear pool of RanGTP both for the assembly of export complexes and the disassembly of import complexes. Accordingly, in order for these processes to proceed, Ran-dependent nuclear import and export assays in vitro require the addition of GTP to produce RanGTP. Notably, no ATP requirement can be detected for these transport processes in vitro. But in vivo, when cells are depleted of ATP by the addition of sodium azide and 2-deoxyglucose to block ATP production by oxidative phosphorylation and glycolysis, respectively, Ran-dependent nuclear import and export are rapidly inhibited. This raised the question of whether there is an ATP requirement for these nuclear transport pathways in an intact cell that has remained undetected in vitro. Here we report that the free (but not total) GTP concentration rapidly drops to an undetectable level upon ATP depletion as does the availability of RanGTP. Our conclusion is that the inhibition of Ran-dependent nuclear transport observed upon ATP depletion in vivo results from a shortage of RanGTP rather than the inhibition of some ATP-dependent process

Assessing the Risk of SARS-CoV-2 Transmission via Surgical Electrocautery Plume

This quality improvement study used a nonhuman subject research approach to examine whether SARS-CoV-2 from aerosolized virus is present in and potentially transmissible from a electrocautery plume in surgery

Genetic Population Structure Analysis in New Hampshire Reveals Eastern European Ancestry

Genetic structure due to ancestry has been well documented among many divergent human populations. However, the ability to associate ancestry with genetic substructure without using supervised clustering has not been explored in more presumably homogeneous and admixed US populations. The goal of this study was to determine if genetic structure could be detected in a United States population from a single state where the individuals have mixed European ancestry. Using Bayesian clustering with a set of 960 single nucleotide polymorphisms (SNPs) we found evidence of population stratification in 864 individuals from New Hampshire that can be used to differentiate the population into six distinct genetic subgroups. We then correlated self-reported ancestry of the individuals with the Bayesian clustering results. Finnish and Russian/Polish/ Lithuanian ancestries were most notably found to be associated with genetic substructure. The ancestral results were further explained and substantiated using New Hampshire census data from 1870 to 1930 when the largest waves of European immigrants came to the area. We also discerned distinct patterns of linkage disequilibrium (LD) between the genetic groups in the growth hormone receptor gene (GHR). To our knowledge, this is the first time such an investigation has uncovered a strong link between genetic structure and ancestry in what would otherwise be considered a homogenous US population