Precautionary Regulation in Europe and the United States: A Quantitative Comparison

Much attention has been addressed to the question of whether Europe or the United States adopts a more precautionary stance to the regulation of potential environmental, health, and safety risks. Some commentators suggest that Europe is more risk-averse and precautionary, whereas the US is seen as more risk-taking and optimistic about the prospects for new technology. Others suggest that the US is more precautionary because its regulatory process is more legalistic and adversarial, while Europe is more lax and corporatist in its regulations. The flip-flop hypothesis claims that the US was more precautionary than Europe in the 1970s and early 1980s, and that Europe has become more precautionary since then. We examine the levels and trends in regulation of environmental, health, and safety risks since 1970. Unlike previous research, which has studied only a small set of prominent cases selected non-randomly, we develop a comprehensive list of almost 3,000 risks and code the relative stringency of regulation in Europe and the US for each of 100 risks randomly selected from that list for each year from 1970 through 2004. Our results suggest that: (a) averaging over risks, there is no significant difference in relative precaution over the period, (b) weakly consistent with the flip-flop hypothesis, there is some evidence of a modest shift toward greater relative precaution of European regulation since about 1990, although (c) there is a diversity of trends across risks, of which the most common is no change in relative precaution (including cases where Europe and the US are equally precautionary and where Europe or the US has been consistently more precautionary). The overall finding is of a mixed and diverse pattern of relative transatlantic precaution over the period

Spatiotemporal flow instabilities of wormlike micellar solutions in rectangular microchannels

Flow velocimetry measurements are made on a non-shear-banding wormlike micellar solutionwithin high-aspect-ratio rectilinear microchannels over a wide range of imposed steady flow rates.At the lowest and highest flow rates tested, Newtonian-like velocity profiles are measured.However, at intermediate flow rates the velocity field never stabilizes on the timescale of theexperiments (up to several hours). Here, spatiotemporally dependent jets of high velocity fluidare observed to fluctuate within regions of essentially stagnant fluid. The reason for this flowinstability remains undetermined, but it has significant consequences for many industrialapplications and also for microfluidic rheometry of complex fluids

The nonlinear time-dependent response of isotactic polypropylene

Tensile creep tests, tensile relaxation tests and a tensile test with a constant rate of strain are performed on injection-molded isotactic polypropylene at room temperature in the vicinity of the yield point. A constitutive model is derived for the time-dependent behavior of semi-crystalline polymers. A polymer is treated as an equivalent network of chains bridged by permanent junctions. The network is modelled as an ensemble of passive meso-regions (with affine nodes) and active meso-domains (where junctions slip with respect to their positions in the bulk medium with various rates). The distribution of activation energies for sliding in active meso-regions is described by a random energy model. Adjustable parameters in the stress--strain relations are found by fitting experimental data. It is demonstrated that the concentration of active meso-domains monotonically grows with strain, whereas the average potential energy for sliding of junctions and the standard deviation of activation energies suffer substantial drops at the yield point. With reference to the concept of dual population of crystalline lamellae, these changes in material parameters are attributed to transition from breakage of subsidiary (thin) lamellae in the sub-yield region to fragmentation of primary (thick) lamellae in the post-yield region of deformation.Comment: 29 pages, 12 figure

Tensile Fracture of Welded Polymer Interfaces: Miscibility, Entanglements and Crazing

Large-scale molecular simulations are performed to investigate tensile failure of polymer interfaces as a function of welding time $t$. Changes in the tensile stress, mode of failure and interfacial fracture energy $G_I$ are correlated to changes in the interfacial entanglements as determined from Primitive Path Analysis. Bulk polymers fail through craze formation, followed by craze breakdown through chain scission. At small $t$ welded interfaces are not strong enough to support craze formation and fail at small strains through chain pullout at the interface. Once chains have formed an average of about one entanglement across the interface, a stable craze is formed throughout the sample. The failure stress of the craze rises with welding time and the mode of craze breakdown changes from chain pullout to chain scission as the interface approaches bulk strength. The interfacial fracture energy $G_I$ is calculated by coupling the simulation results to a continuum fracture mechanics model. As in experiment, $G_I$ increases as $t^{1/2}$ before saturating at the average bulk fracture energy $G_b$. As in previous simulations of shear strength, saturation coincides with the recovery of the bulk entanglement density. Before saturation, $G_I$ is proportional to the areal density of interfacial entanglements. Immiscibiltiy limits interdiffusion and thus suppresses entanglements at the interface. Even small degrees of immisciblity reduce interfacial entanglements enough that failure occurs by chain pullout and $G_I \ll G_b$

Microdevices for extensional rheometry of low viscosity elastic liquids : a review

Extensional flows and the underlying stability/instability mechanisms are of extreme relevance to the efficient operation of inkjet printing, coating processes and drug delivery systems, as well as for the generation of micro droplets. The development of an extensional rheometer to characterize the extensional properties of low viscosity fluids has therefore stimulated great interest of researchers, particularly in the last decade. Microfluidics has proven to be an extraordinary working platform and different configurations of potential extensional microrheometers have been proposed. In this review, we present an overview of several successful designs, together with a critical assessment of their capabilities and limitations

The impact of the Calman–Hine report on the processes and outcomes of care for Yorkshire's colorectal cancer patients

The 1995 Calman–Hine plan outlined radical reform of the UK's cancer services with the aim of improving outcomes and reducing inequalities in NHS cancer care. Its main recommendation was to concentrate care into the hands of site-specialist, multi-disciplinary teams. This study aimed to determine if the implementation of Calman–Hine cancer teams was associated with improved processes and outcomes of care for colorectal cancer patients. The design included longitudinal survey of 13 colorectal cancer teams in Yorkshire and retrospective study of population-based data collected by the Northern and Yorkshire Cancer Registry and Information Service. The population was all colorectal cancer patients diagnosed and treated in Yorkshire between 1995 and 2000. The main outcome measures were: variations in the use of anterior resection and preoperative radiotherapy in rectal cancer, chemotherapy in Dukes stage C and D patients, and five-year survival. Using multilevel models, these outcomes were assessed in relation to measures of the extent of Calman–Hine implementation throughout the study period, namely: (i) each team's degree of adherence to the Manual of Cancer Service Standards (which outlines the specification of the ‘ideal’ colorectal cancer team) and (ii) the extent of site specialisation of each team's surgeons. Variation was observed in the extent to which the colorectal cancer teams in Yorkshire had conformed to the Calman–Hine recommendations. An increase in surgical site specialisation was associated with increased use of preoperative radiotherapy (OR=1.43, 95% CI=1.04–1.98, P<0.04) and anterior resection (OR=1.43, 95% CI=1.16–1.76, P<0.01) in rectal cancer patients. Increases in adherence to the Manual of Cancer Service Standards was associated with improved five-year survival after adjustment for the casemix factors of age, stage of disease, socioeconomic status and year of diagnosis, especially for colon cancer (HR=0.97, 95% CI=0.94–0.99 P<0.01). There was a similar trend of improved survival in relation to increased surgical site specialisation for rectal cancer, although the effect was not statistically significant (HR=0.93, 95% CI=0.84–1.03, P=0.15). In conclusion, the extent of implementation of the Calman–Hine report has been variable and its recommendations are associated with improvements in processes and outcomes of care for colorectal cancer patients

Promjene citokroma P450 jetre i mozga nakon višekratne primjene kokaina, samog ili u kombinaciji s nifedipinom

The objective of this study was to evaluate possible changes caused by multiple cocaine administration, alone and in combination with 1,4-dihydropiridine calcium channel blocker nifedipine, on cytochrome P450 levels both in the brain and liver. The experiment was done on male Wistar rats divided in four groups: control, treated with nifedipine (5 mg kg-1 i.p. for five days), treated with cocaine (15 mg kg-1 i.p. for five days), and treated with nifedipine and 30 minutes later with cocaine (also for five days). Total cytochrome P450 was measured spectrometrically in liver and brain microsomes. Multiple administration of cocaine alone and in combination with nifedipine did not change the brain P450 significantly. In the liver, nifedipine significantly increased P450 by 28 % vs. control. In contrast, cocaine significantly decreased P450 by 17 % vs. control. In animals treated with nifedipine and cocaine, cytochrome P450 increased 11 % (p<0.01) vs. control, decreased 12.5 % (p<0.001) vs. nifedipine group and increased 34 % (p<0.0001) vs. cocaine group. These results suggest that the cocaine and nifedipine interact at the metabolic level.Cilj je ovog istraživanja bio ocijeniti moguće promjene uzrokovane višestrukom primjenom kokaina kao jedinog agensa odnosno u kombinaciji s nifedipinom, 1,4-dihidropiridinskim blokatorom kalcijevih kanala, na razine citokroma P450 u mozgu i jetri štakora. Životinje (mužjaci Wistar štakora) podijeljene su u četiri skupine: kontrolnu skupinu, skupinu koja je primala nifedipin (5 mg kg-1 ip. pet dana), skupinu koja je primala kokain (15 mg kg-1 ip. pet dana) i skupinu koja je primala nifedipin te pola sata kasnije kokain (također pet dana). Ukupna količina citokroma P450 mjerena je spektrofotometrijski u mikrosomima jetre i mozga. Višestruka primjena samo kokaina odnosno u kombinaciji s nifedipinom nije značajno promijenila razine citokroma P450 u mozgu. U jetri je međutim nifedipin u odnosu na kontrolnu skupinu uzrokovao povišenje razina P450, za statistički značajnih 28 %. Kokain je uzrokovao statistički značajan pad razine P450 za 17 % u odnosu na kontrolnu skupinu. U životinja koje su primale kombinaciju nifedipina i kokaina razina citokroma P450 narasla je za 11 % (p<0.01) u odnosu na kontrolu, bila je 12.5 % (p<0.001) niža u odnosu na skupinu koja je primala nifedipin te viša za 34 % (p<0.0001) u odnosu na skupinu koja je primala samo kokain. Rezultati ovog istraživanja upućuju na interakcije ovih spojeva koje se odvijaju na razini metabolizm

Lung cancer referral patterns in the former Yorkshire region of the UK

The purpose of this study was to find out what proportion of patients are referred as lung cancer guidelines assume, whether different referral pathways result in different management and what proportion of patients are seen within recommended time intervals between referral and treatment. A randomly selected sample of 400 lung cancer cases registered with the former Yorkshire Cancer Registry database in 1993 was selected for casenote analysis. Mode of presentation, speciality of initial referral, treatment by specialist, time intervals for key points in the referral pathways were analyzed. A total of 362 (90.5%) of case-notes were available. Less than half of lung cancer patients (173, 47.8%) presented to hospital with a chest X-ray diagnosis of lung cancer. Forty-one (11.3%) presented as self-referrals to Accident and Emergency and the remainder were referred without a diagnosis of lung cancer by other routes, mainly via GPs. Patients who did not present initially with a lung cancer diagnosis were less likely to receive specialist care (62% : 96%), or have their diagnosis histologically confirmed (57.1% : 80.3%) or receive surgery or radical radiotherapy (6.9% : 13.9%). Nine per cent of all 362 patients did not receive a specialist opinion. Eighty per cent of patients referred by a GP with CXR suspected lung cancer were seen at hospital within 2 weeks. Only 32.4% of those receiving active treatment were treated within 8 weeks of clinical diagnosis or first hospital visit. Lung cancer patients presenting to hospital without a suspicious CXR are less likely to have specialist care, histological confirmation of their cancer and have lower rates of active treatment (surgery, any radiotherapy or chemotherapy)

Application of activated barrier hopping theory to viscoplastic modeling of glassy polymers

YesAn established statistical mechanical theory of amorphous polymer deformation has been incorporated as a plastic mechanism into a constitutive model and applied to a range of polymer mechanical deformations. The temperature and rate dependence of the tensile yield of PVC, as reported in early studies, has been modeled to high levels of accuracy. Tensile experiments on PET reported here are analyzed similarly and good accuracy is also achieved. The frequently observed increase in the gradient of the plot of yield stress against logarithm of strain rate is an inherent feature of the constitutive model. The form of temperature dependence of the yield that is predicted by the model is found to give an accurate representation. The constitutive model is developed in two-dimensional form and implemented as a user-defined subroutine in the finite element package ABAQUS. This analysis is applied to the tensile experiments on PET, in some of which strain is localized in the form of shear bands and necks. These deformations are modeled with partial success, though adiabatic heating of the instability causes inaccuracies for this isothermal implementation of the model. The plastic mechanism has advantages over the Eyring process, is equally tractable,and presents no particular difficulties in implementation with finite elements.F. Boutenel acknowledges an Erasmus Programme Scholarshi

Inertio-elastic focusing of bioparticles in microchannels at high throughput

Controlled manipulation of particles from very large volumes of fluid at high throughput is critical for many biomedical, environmental and industrial applications. One promising approach is to use microfluidic technologies that rely on fluid inertia or elasticity to drive lateral migration of particles to stable equilibrium positions in a microchannel. Here, we report on a hydrodynamic approach that enables deterministic focusing of beads, mammalian cells and anisotropic hydrogel particles in a microchannel at extremely high flow rates. We show that on addition of micromolar concentrations of hyaluronic acid, the resulting fluid viscoelasticity can be used to control the focal position of particles at Reynolds numbers up to Re≈10,000 with corresponding flow rates and particle velocities up to 50 ml min[superscript −1] and 130 m s[superscript −1]. This study explores a previously unattained regime of inertio-elastic fluid flow and demonstrates bioparticle focusing at flow rates that are the highest yet achieved.National Institute for Biomedical Imaging and Bioengineering (U.S.) (P41 BioMicroElectroMechanical Systems Resource Center)National Institute for Biomedical Imaging and Bioengineering (U.S.) (P41 EB002503)National Science Foundation (U.S.). Graduate Research FellowshipUnited States. Army Research Office (Institute for Collaborative Biotechnologies Grant W911NF-09-0001