An optimal internet location strategy for markets with different tax rates

The traditional view that a high sales tax rate reduces trade by driving a wedge between the purchase and sale price may not apply to internet commerce for two reasons. The first reason is that the sales tax paid by buyers purchasing via the internet is determined by the tax rate in the region of the buyer. The second reason is that a high sales tax may lower the before-tax price if sellers absorb part of the tax. Taken together, this implies that internet distributors may profitably target customers in regions with low tax rates by locating their selling addresses in high tax regions. Consequently the optimal marketing strategy for a global internet distributor may include siting selling locations in regions with high tax rates in order to target customers in regions with low tax rates. An empirical analysis of the European car market suggests that this is more than a remote theoretical possibility by demonstrating that the before-tax prices recommended by manufacturers for new cars are lower in high tax countries

A Quantitative Study of Intervertebral Disc Morphologic Changes Following Plasma‐Mediated Percutaneous Discectomy

Objective To quantitatively evaluate interval magnetic resonance imaging ( MRI ) changes in disc morphology following plasma‐mediated percutaneous discectomy. Design/Setting A retrospective comparison of pretreatment and posttreatment MRIs at a single university spine clinic. Subjects From a group of 60 consecutively treated patients, 15 met the study inclusion and exclusion criteria. All had either failed treatment or had other clinical reasons for a posttreatment MRI . Methods Two independent physicians electronically measured disc protrusion size and disc height at the treatment discs and adjacent discs on pre‐ and posttreatment MRI scans. Additionally, images were compared for gross anatomic changes including disc degeneration by P firrman classification, new disc herniations, high intensity zone ( HIZ ), vertebral endplate changes, post‐contrast enhancement, and changes in segmental alignment. P earson r correlation was used to determine interobserver reliability between the two physicians' MRI measurements. Paired t ‐tests were calculated for comparisons of pre‐ and posttreatment MRI measurements, and an ANOVA was performed for comparison of pre‐ to posttreatment changes in disc height measurements at treatment levels relative to adjacent levels. Results Correlation was high for measurement of disc height change ( r  = 0.89; P  < 0.0001) and good for anteroposterior protrusion size change ( r  = 0.51; P  = 0.0512). Disc height at treated discs demonstrated a small but statistically significant mean interval reduction of 0.48 mm ( P  = 0.0018). This remained significant when compared with the adjacent control discs ( P  < 0.0001). Pretreatment mean disc protrusion size (4.74 mm; range 3.75–6.55 mm) did not differ significantly ( P  = 0.1145) from posttreatment protrusion size (4.42 mm; range 2.55–7.95 mm). Gross anatomic changes at treatment levels included reduced disc protrusion size (N = 6), enlarged protrusion (N = 3), resolution of HIZ (N = 3), and improvement in endplate signal changes (N = 1). Also, 11/15 posttreatment MRIs included post‐contrast images that showed epidural fibrosis (N = 1), rim enhancement (N = 2), and enhancement of the posterior annulus (N = 4). Conclusions Based on MRI examinations, subtle anatomic changes may occur following plasma‐mediated percutaneous discectomy. Further study is required to determine the clinical relevance of these changes.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/109360/1/pme12525.pd

Gold as an inflation hedge?

This paper attempts to reconcile an apparent contradiction between short-run and long-run movements in the price of gold. The theoretical model suggests a set of conditions under which the price of gold rises over time at the general rate of inflation and hence be an effective hedge against inflation. The model also demonstrates that short-run changes in the gold lease rate, the real interest rate, convenience yield, default risk, the covariance of gold returns with other assets and the dollar/world exchange rate can disturb this equilibrium relationship and generate short-run price volatility. Using monthly gold price data (1976-1999), and cointegration regression techniques, an empirical analysis confirms the central hypotheses of the theoretical model

Non-invasive monitoring of tissue oxygenation during laparoscopic donor nephrectomy

<p>Abstract</p> <p>Background</p> <p>Standard methods for assessment of organ viability during surgery are typically limited to visual cues and tactile feedback in open surgery. However, during laparoscopic surgery, these processes are impaired. This is of particular relevance during laparoscopic renal donation, where the condition of the kidney must be optimized despite considerable manipulation. However, there is no <it>in vivo </it>methodology to monitor renal parenchymal oxygenation during laparoscopic surgery.</p> <p>Methods</p> <p>We have developed a method for the real time, <it>in vivo</it>, whole organ assessment of tissue oxygenation during laparoscopic nephrectomy to convey meaningful biological data to the surgeon during laparoscopic surgery. We apply the 3-CCD (charge coupled device) camera to monitor qualitatively renal parenchymal oxygenation with potential real-time video capability.</p> <p>Results</p> <p>We have validated this methodology in a porcine model across a range of hypoxic conditions, and have then applied the method during clinical laparoscopic donor nephrectomies during clinically relevant pneumoperitoneum. 3-CCD image enhancement produces mean region of interest (ROI) intensity values that can be directly correlated with blood oxygen saturation measurements (R²> 0.96). The calculated mean ROI intensity values obtained at the beginning of the laparoscopic nephrectomy do not differ significantly from mean ROI intensity values calculated immediately before kidney removal (<it>p </it>> 0.05).</p> <p>Conclusion</p> <p>Here, using the 3-CCD camera, we qualitatively monitor tissue oxygenation. This means of assessing intraoperative tissue oxygenation may be a useful method to avoid unintended ischemic injury during laparoscopic surgery. Preliminary results indicate that no significant changes in renal oxygenation occur as a result of pneumoperitoneum.</p

Assessment of online water-soluble brown carbon measuring systems for aircraft sampling

Brown carbon (BrC) consists of particulate organic species that preferentially absorb light at visible and ultraviolet wavelengths. Ambient studies show that as a component of aerosol particles, BrC affects photochemical reaction rates and regional to global climate. Some organic chromophores are especially toxic, linking BrC to adverse health effects. The lack of direct measurements of BrC has limited our understanding of its prevalence, sources, evolution, and impacts. We describe the first direct, online measurements of water-soluble BrC on research aircraft by three separate instruments. Each instrument measured light absorption over a broad wavelength range using a liquid waveguide capillary cell (LWCC) and grating spectrometer, with particles collected into water by a particle-into-liquid sampler (CSU PILS-LWCC and NOAA PILS-LWCC) or a mist chamber (MC-LWCC). The instruments were deployed on the NSF C-130 aircraft during WE-CAN 2018 as well as the NASA DC-8 and the NOAA Twin Otter aircraft during FIREX-AQ 2019, where they sampled fresh and moderately aged wildfire plumes. Here, we describe the instruments, calibrations, data analysis and corrections for baseline drift and hysteresis. Detection limits (3σ) at 365 nm were 1.53 Mm−1 (MC-LWCC; 2.5 min sampling time), 0.89 Mm−1 (CSU PILS-LWCC; 30 s sampling time), and 0.03 Mm−1 (NOAA PILS-LWCC; 30 s sampling time). Measurement uncertainties were 28 % (MC-LWCC), 12 % (CSU PILS-LWCC), and 11 % (NOAA PILS-LWCC). The MC-LWCC system agreed well with offline measurements from filter samples, with a slope of 0.91 and R2=0.89. Overall, these instruments provide soluble BrC measurements with specificity and geographical coverage that is unavailable by other methods, but their sensitivity and time resolution can be challenging for aircraft studies where large and rapid changes in BrC concentrations may be encountered

NIRCam coronagraphic Lyot stop: design, fabrication, and testing

The NIRCam instrument on the James Webb Space Telescope (JWST) will provide a coronagraphic imaging capability to search for extrasolar planets in the 2 - 5 microns wavelength range. This capability is realized by a set of Lyot pupil stops with patterns matching the occulting mask located in the JWST intermediate focal plane in the NIRCam optical system. The complex patterns with transparent apertures are made by photolithographic process using a metal coating in the opaque region. The optical density needs to be high for the opaque region, and transmission needs to be high at the aperture. In addition, the Lyot stop needs to operate under cryogenic conditions. We will report on the Lyot stop design, fabrication and testing in this paper

Serum neurofilament dynamics predicts neurodegeneration and clinical progression in presymptomatic Alzheimer's disease

Neurofilament light chain (NfL) is a promising fluid biomarker of disease progression for various cerebral proteopathies. Here we leverage the unique characteristics of the Dominantly Inherited Alzheimer Network and ultrasensitive immunoassay technology to demonstrate that NfL levels in the cerebrospinal fluid (n = 187) and serum (n = 405) are correlated with one another and are elevated at the presymptomatic stages of familial Alzheimer's disease. Longitudinal, within-person analysis of serum NfL dynamics (n = 196) confirmed this elevation and further revealed that the rate of change of serum NfL could discriminate mutation carriers from non-mutation carriers almost a decade earlier than cross-sectional absolute NfL levels (that is, 16.2 versus 6.8 years before the estimated symptom onset). Serum NfL rate of change peaked in participants converting from the presymptomatic to the symptomatic stage and was associated with cortical thinning assessed by magnetic resonance imaging, but less so with amyloid-β deposition or glucose metabolism (assessed by positron emission tomography). Serum NfL was predictive for both the rate of cortical thinning and cognitive changes assessed by the Mini-Mental State Examination and Logical Memory test. Thus, NfL dynamics in serum predict disease progression and brain neurodegeneration at the early presymptomatic stages of familial Alzheimer's disease, which supports its potential utility as a clinically useful biomarker

Adam Smith’s Green Thumb and Malthus’ Three Horsemen: Cautionary tales from classical political economy

This essay identifies a contradiction between the flourishing interest in the environmental economics of the classical period and a lack of critical parsing of the works of its leading representatives. Its focus is the work of Adam Smith and Thomas Malthus. It offers a critical analysis of their contribution to environmental thought and surveys the work of their contemporary devotees. It scrutinizes Smith's contribution to what Karl Polanyi termed the "economistic fallacy," as well as his defenses of class hierarchy, the "growth imperative" and consumerism. It subjects to critical appraisal Malthus's enthusiasm for private property and the market system, and his opposition to market regulation. While Malthus's principal attraction to ecological economists lies in his having allegedly broadened the scope of economics, and in his narrative of scarcity, this article shows that he, in fact, narrowed the scope of the discipline and conceptualized scarcity in a reified and pseudo-scientific way

BDNF Val66Met moderates memory impairment, hippocampal function and tau in preclinical autosomal dominant Alzheimer’s disease

The brain-derived neurotrophic factor ( BDNF ) Val66Met polymorphism is implicated in synaptic excitation and neuronal integrity, and has previously been shown to moderate amyloid-β-related memory decline and hippocampal atrophy in preclinical sporadic Alzheimer’s disease. However, the effect of BDNF in autosomal dominant Alzheimer’s disease is unknown. We aimed to determine the effect of BDNF Val66Met on cognitive function, hippocampal function, tau and amyloid-β in preclinical autosomal dominant Alzheimer’s disease. We explored effects of apolipoprotein E ( APOE ) ε4 on these relationships. The Dominantly Inherited Alzheimer Network conducted clinical, neuropsychological, genetic, biomarker and neuroimaging measures at baseline in 131 mutation non-carriers and 143 preclinical autosomal dominant Alzheimer’s disease mutation carriers on average 12 years before clinical symptom onset. BDNF genotype data were obtained for mutation carriers (95 Val 66 homozygotes, 48 Met 66 carriers). Among preclinical mutation carriers, Met 66 carriers had worse memory performance, lower hippocampal glucose metabolism and increased levels of cerebrospinal fluid tau and phosphorylated tau (p-tau) than Val 66 homozygotes. Cortical amyloid-β and cerebrospinal fluid amyloid-β 42 levels were significantly different from non-carriers but did not differ between preclinical mutation carrier Val 66 homozygotes and Met 66 carriers. There was an effect of APOE on amyloid-β levels, but not cognitive function, glucose metabolism or tau. As in sporadic Alzheimer’s disease, the deleterious effects of amyloid-β on memory, hippocampal function, and tau in preclinical autosomal dominant Alzheimer’s disease mutation carriers are greater in Met 66 carriers. To date, this is the only genetic factor found to moderate downstream effects of amyloid-β in autosomal dominant Alzheimer’s disease