Ultrafast microfluidics using surface acoustic waves

We demonstrate that surface acoustic waves (SAWs), nanometer amplitude Rayleigh waves driven at megahertz order frequencies propagating on the surface of a piezoelectric substrate, offer a powerful method for driving a host of extremely fast microfluidic actuation and micro∕bioparticle manipulation schemes. We show that sessile drops can be translated rapidly on planar substrates or fluid can be pumped through microchannels at 1–10 cm∕s velocities, which are typically one to two orders quicker than that afforded by current microfluidic technologies. Through symmetry-breaking, azimuthal recirculation can be induced within the drop to drive strong inertial microcentrifugation for micromixing and particle concentration or separation. Similar micromixing strategies can be induced in the same microchannel in which fluid is pumped with the SAW by merely changing the SAW frequency to rapidly switch the uniform through-flow into a chaotic oscillatory flow by exploiting superpositioning of the irradiated sound waves from the sidewalls of the microchannel. If the flow is sufficiently quiescent, the nodes of the transverse standing wave that arises across the microchannel also allow for particle aggregation, and hence, sorting on nodal lines. In addition, the SAW also facilitates other microfluidic capabilities. For example, capillary waves excited at the free surface of a sessile drop by the SAW underneath it can be exploited for micro∕nanoparticle collection and sorting at nodal points or lines at low powers. At higher powers, the large accelerations off the substrate surface as the SAW propagates across drives rapid destabilization of the drop free surface giving rise to inertial liquid jets that persist over 1–2 cm in length or atomization of the entire drop to produce 1–10 μm monodispersed aerosol droplets, which can be exploited for ink-jet printing, mass spectrometry interfacing, or pulmonary drug delivery. The atomization of polymer∕protein solutions can also be used for the rapid synthesis of 150–200 nm polymer∕protein particles or biodegradable polymeric shells in which proteins, peptides, and other therapeutic molecules are encapsulated within for controlled release drug delivery. The atomization of thin films behind a translating drop containing polymer solutions also gives rise to long-range spatial ordering of regular polymer spots whose size and spacing are dependent on the SAW frequency, thus offering a simple and powerful method for polymer patterning without requiring surface treatment or physical∕chemical templating.     

Rapid production of protein-loaded biodegradable microparticles using surface acoustic waves

We present a straightforward and rapid surface acoustic wave (SAW) atomization-based technique for encapsulating proteins into 10 μm order particles composed of a biodegradable polymeric excipient, using bovine serum albumin (BSA) as an exemplar. Scans obtained from confocal microscopy provide qualitative proof of encapsulation and show the fluorescent conjugated protein to be distributed in a relatively uniform manner within the polymer shell. An ELISA assay of the collected particles demonstrates that the BSA survives the atomization, particle formation, and collection process with a yield of approximately 55%. The SAW atomization universally gave particles with a textured morphology, and increasing the frequency and polymer concentration generally gave smaller particles (to 3 μm average) with reduced porosity.     

Investigation of behavior and perception of digital library users: A cognitive style perspective

Cognitive style is an influential factor in users’ information seeking. The study presented in this paper examines how users’ cognitive styles affect their behavior and perception in digital libraries. Fifty participants took part in this study. Two dimensions of cognitive styles were considered: (a) Field Dependence/Independence; (2) Verbalizer/Imager. The results showed that Intermediate users and Verbalizers have not only more positive perception, but they also complete the tasks in effective ways. Implications for the design of personalized digital libraries are also discussed.     

Visions and versions of governing biomedicine: narratives on power structures, decision-making and public participation in the field of biomedical technology in the Austrian context

In recent years, governance and public participation have developed into key notions within both policy discourse and academic analysis. While there is much discussion on developing new modes of governance and public participation, little empirical attention is paid to the public's perception of models, possibilities and limits of participation and governance. Building on focus group data collected in Austria within the framework of a European project, this paper explores lay people's visions and versions of government, governance and participation for two biomedical technologies: post-natal genetic testing and organ transplantation. Building on this analysis, we show that people situate their assessments of public participation against the background of rather complex lay models of the governance and government of the respective technology. Because these models are very different for the two technologies, participation also had very different connotations, which were deeply intertwined with each socio-technical system. Building on these findings we argue for a more technology-sensitive approach to public participation.     

Effect of vitamin E supplementation on oxidative stress in hemodialysis patients

Hemodialysis represents a chronic stress status for its recipients. Many hypotheses state that this may be associated with oxidative stress. Thus, there may be deficiency of antioxidants like erythrocytic superoxide dismutase, catalase, vitamin E or increased generation of free radicals like superoxide anions. A study was carried out to investigate oxidant and antioxidant status in chronic renal failure patients undergoing hemodialysis and effect of vitamin E supplementation on these two status. Blood samples were collected from patients before and after hemodialysis and from controls. The samples were analyzed for quantitation of MDA as index of lipid peroxide, nitric oxide, vitamin E, vitamin C and enzymatic antioxidants namely erythrocyte SOD and catalase. As compared to controls, the levels of serum MDA were significantly increased and activities of erythrocyte SOD and catalase, levels of serum nitric oxide, serum vitamin E and plasma vitamin C were significantly decreased both before and after hemodialysis. The efficiency of vitamin E therapy in hemodialysis patients was assessed by re-evaluating oxidant and antioxidant status of same patients after supplementation of vitamin E. Vitamin E supplementation caused decrease in serum MDA and increase in levels of serum nitric oxide, vitamin E, vitamin C and activities of erythrocytic SOD and catalase. Our results suggest the presence of oxidative stress and the possible preventive role of vitamin E therapy in hemodialysis patients.     

Blood glutathione levels in head and neck malignancies

Blood glutathione was estimated in fifty patients of head and neck cancer in the age group of 18–76 years and the results were compared with a group of normal healthy controls. Mean blood glutathione level was found to be significantly lowered in patients than the controls. Irrespective of the site, TNM classification, histopathology, and character of lesion, fall in blood glutathione was nearly same in all the patients. The mean level was significantly increased after radiotherapy when compared with the levels before radiotherapy. The decreased levels of GSH in-patients with head and neck cancer, observed in the present study, may be due to its increased utilization by the cells. The results suggest that patients with head and neck cancer have increased oxidative stress.     

Whitehead's Contribution to Ecological Thought: Some Unrealized Possibilities

The organizers of this conference have given me a difficult task: that of finding heretofore unfound implications of Whitehead's philosophy for environmental thought. The task is not difficult because implications of Whitehead's philosophy for environmental thought are hard to find. They are easy to find. The problem is that so many people have found them that finding something new to say is not easy.In what follows, however, some new implications are actually ferreted out. They fall under three headings: a) the interrelations between three ways of thinking about the environment: bioregionalism, land ethics, and the philosophy of organism; b) the implications of Whitehead's philosophy of organism for environmental aesthetics; and c) the implications of Whitehead's philosophy of organism for human communities (sustainable communities) viewed as interfused with living nature.     

Stability analysis of nonlinear control systems with characteristics equations having complex coefficients

In this paper, the stability equation method is applied to the analysis of nonlinear systems with characteristics equations having complex coefficients. Three types of systems are studied: those with unstable open-loop poles, unstable characteristics roots or an equal number of open-loop poles and zeros.     

Factors associated with concussion-symptom knowledge and attitudes toward concussion care seeking in a national survey of parents of middle-school children in the US

Background:Developing appropriate concussion prevention and management paradigms in middle school(MS)settings requires understanding parents’general levels of concussion-related knowledge and attitudes.This study examined factors associated with concussion-symptom knowledge and care-seeking attitudes among parents of MS children(aged 10-15 years).Methods:A panel of 1224 randomly selected U.S.residents,aged ≥18 years and identifying as parents of MS children,completed an online questionnaire capturing parental and child characteristics.The parents’concussion-symptom knowledge was measured using 25 questions,with possible answers being“yes”,“maybe”,and“no”.Correct answers earned 2 points,“maybe”answers earned 1 point,and incorrect answers earned 0 point(range:0-50;higher scores=better knowledge).Concussion care-seeking attitudes were also collected using five 7-point scale items(range:5-35;higher scores=more positive attitudes).Multivariable ordinal logistic regression models identified predictors of higher scores.Models met proportional odds assumptions.Adjusted odds ratios(aORs)with 95%confidence intervals(95%CIs)(excluding 1.00)were deemed statistically significant.Results:Median scores were 39(interquartile range:32-44)for symptom knowledge and 32(interquartile range:28-35)for care-seeking attitude.In multivariable models,odds of better symptom knowledge were higher in women vs.men(aOR=2.28;95%CI:1.71-3.05),white/non-Hispanics vs.other racial or ethnic groups(aOR=1.88;95%CI:1.42-2.49),higher parental age(10-year-increase aOR=1.47;95%CI:1.26-1.71),and greater competitiveness(10%-scale-increase aOR=1.24;95%CI:1.13-1.36).Odds of more positive care-seeking attitudes were higher in white/non-Hispanics vs.other racial or ethnic groups(aOR=1.45;95%CI:1.06-1.99)and in older parental age(10-year-increase aOR=1.24;95%CI:1.05-1.47).Conclusion:Characteristics of middle school children’s parents(e.g.,sex,race or ethnicity,age)are associated with their concussion-symptom knowledge and care-seeking attitudes.Parents’variations in concussion knowledge and attitudes warrant tailored concussion education and prevention.     

Defining'science-based targets'

The 2015 Paris Agreement to keep global warming well below 2℃above pre-industrial levels and aim towards limiting warming to 1.5℃marked a wa-tershed in planetar...