Polymer Release out of a Spherical Vesicle through a Pore

Translocation of a polymer out of curved surface or membrane is studied via mean first passage time approach. Membrane curvature gives rise to a constraint on polymer conformation, which effectively drives the polymer to the outside of membrane where the available volume of polymer conformational fluctuation is larger. Considering a polymer release out of spherical vesicle, polymer translocation time $\tau$ is changed to the scaling behavior $\tau\sim L^2$ for $R<R_G$, from $\tau\sim L^3$ for $R\gg R_G$, where $L$ is the polymer contour length and $R$, $R_G$ are vesicle radius and polymer radius of gyration respectively. Also the polymer capture into a spherical budd is studied and possible apparatus for easy capture is suggested.Comment: 14 pages RevTeX, 6 postscript figures, published in Phys. Rev. E 57, 730 (1998

Joint Taxation and the Labour Supply of Married Women: Evidence from the Canadian Tax Reform of 1988

The Canadian federal tax reform of 1988 replaced a spousal tax exemption with a non-refundable tax credit. This reduced the "jointness" of the tax system: after the reform, secondary earners' effective "first dollar" marginal tax rates no longer depended on the marginal tax rates of their spouses. In practice, the effective "first dollar" marginal tax rates faced by women with high income husbands were particularly reduced. Using difference-in-difference estimators, we find a significant increase in labour force participation among women married to higher income husbands.Labour supply, Canadian tax reform, Married women, Difference-in-difference

Joint Taxation and the Labour Supply of Married Women: Evidence from the Canadian Tax Reform of 1988

The Canadian federal tax reform of 1988 replaced a spousal tax exemption with a non-refundable tax credit. This reduced the "jointness" of the tax system: after the reform, secondary earners' effective "first dollar" marginal tax rates no longer depended on the marginal tax rates of their spouses. In practice, the effective "first dollar" marginal tax rates faced by women with high income husbands were particularly reduced. Using difference-in-difference estimators, we find a significant increase in labour force participation among women married to higher income husbands.Labour supply, Canadian tax reform, Married women, Difference-in-difference

New Vector Boson Near the Z-pole and the Puzzle in Precision Electroweak Data

We show that a Z' with suppressed couplings to the electron compared to the Z-boson, with couplings to the b-quark, and with a mass close to the mass of the Z-boson, provides an excellent fit to forward-backward asymmetry of the b-quark and R_b measured on the Z-pole and $\pm 2$ GeV off the Z-pole, and to A_e obtained from the measurement of left-right asymmetry for hadronic final states. It also leads to a significant improvement in the total hadronic cross section on the Z-pole and R_b measured at energies above the Z-pole. In addition, with a proper mass, it can explain the excess of $Zb\bar b$ events at LEP in the 90-105 GeV region of the $b\bar b$ invariant mass.Comment: 10 pages, 1 figur

Z' near the Z-pole

We present a fit to precision electroweak data in the standard model extended by an additional vector boson, Z', with suppressed couplings to the electron compared to the Z boson, with couplings to the b-quark, and with mass close to the mass of the Z boson. This scenario provides an excellent fit to forward-backward asymmetry of the b-quark measured on the Z-pole and \pm 2 GeV off the Z-pole, and to lepton asymmetry, A_e, obtained from the measurement of left-right asymmetry for hadronic final states, and thus it removes the tension in the determination of the weak mixing angle from these two measurements. It also leads to a significant improvement in the total hadronic cross section on the Z-pole and R_b measured at energies above the Z-pole. We explore in detail properties of the Z' needed to explain the data and present a model for Z' with required couplings. The model preserves standard model Yukawa couplings, it is anomaly free and can be embedded into grand unified theories. It allows a choice of parameters that does not generate any flavor violating couplings of the Z' to standard model fermions. Out of standard model couplings, it only negligibly modifies the left-handed bottom quark coupling to the Z boson and the 3rd column of the CKM matrix. Modifications of standard model couplings in the charged lepton sector are also negligible. It predicts an additional down type quark, D, with mass in a few hundred GeV range, and an extra lepton doublet, L, possibly much heavier than the D quark. We discuss signatures of the Z' at the Large Hadron Collider and calculate the Z'b production cross section which is the dominant production mechanism for the Z'.Comment: 26 pages, 18 figures, minor modifications, one fig. added, results unchange

Physician Labour Supply in Canada: a Cohort Analysis

This paper employs cohort analysis to examine the relative importance of different factors in explaining changes in the number of hours spent in direct patient care by Canadian general/ family practitioners (GP/FPs) over the period 1982 to 2002. Cohorts are defined by year of graduation from medical school. The results for male GP/FPs indicate that: there is little age effect on hours of direct patient care, especially among physicians aged 35 to 55; there is no strong cohort effect on hours of direct patient care; but there is a secular decline in hours of direct patient care over the period. The results for female GP/FPs indicate that: female physicians on average work fewer hours than male physicians; there is a clear age effect on hours of direct patient care; there is no strong cohort effect; there has been little secular change in average hours of direct patient care. The changing behaviour of male GP/FPs accounted for a greater proportion of the overall decline in hours of direct patient care from the 80’s through the mid 90’s than did the growing proportion of female GP/FPs in the physician stock.physician, labour supply, hours, cohorts

Physician Labour Supply in Canada: a Cohort Analysis

This paper employs cohort analysis to examine the relative importance of different factors in explaining changes in the number of hours spent in direct patient care by Canadian general/ family practitioners (GP/FPs) over the period 1982 to 2002. Cohorts are defined by year of graduation from medical school. The results for male GP/FPs indicate that: there is little age effect on hours of direct patient care, especially among physicians aged 35 to 55; there is no strong cohort effect on hours of direct patient care; but there is a secular decline in hours of direct patient care over the period. The results for female GP/FPs indicate that: female physicians on average work fewer hours than male physicians; there is a clear age effect on hours of direct patient care; there is no strong cohort effect; there has been little secular change in average hours of direct patient care. The changing behaviour of male GP/FPs accounted for a greater proportion of the overall decline in hours of direct patient care from the 80’s through the mid 90’s than did the growing proportion of female GP/FPs in the physician stock.physician, labour supply, hours, cohorts

Quantification of Local Hemodynamic Alterations Caused by Virtual Implantation of Three Commercially Available Stents for the Treatment of Aortic Coarctation

Patients with coarctation of the aorta (CoA) are prone to morbidity including atherosclerotic plaque that has been shown to correlate with altered wall shear stress (WSS) in the descending thoracic aorta (dAo). We created the first patient-specific computational fluid dynamics (CFD) model of a CoA patient treated by Palmaz stenting to date, and compared resulting WSS distributions to those from virtual implantation of Genesis XD and modified NuMED CP stents, also commonly used for CoA. CFD models were created from magnetic resonance imaging, fluoroscopy and blood pressure data. Simulations incorporated vessel deformation, downstream vascular resistance and compliance to match measured data and generate blood flow velocity and time-averaged WSS (TAWSS) results. TAWSS was quantified longitudinally and circumferentially in the stented region and dAo. While modest differences were seen in the distal portion of the stented region, marked differences were observed downstream along the posterior dAo and depended on stent type. The Genesis XD model had the least area of TAWSS values exceeding the threshold for platelet aggregation in vitro, followed by the Palmaz and NuMED CP stents. Alterations in local blood flow patterns and WSS imparted on the dAo appear to depend on the type of stent implanted for CoA. Following confirmation in larger studies, these findings may aid pediatric interventional cardiologists in selecting the most appropriate stent for each patient, and ultimately reduce long-term morbidity following treatment for CoA by stenting