Cerebral blood-flow monitor for use in neonatal intensive care units

The implementation of a real-time multichannel system for monitoring cerebral blood-flow is described. The instrument relies on a completely modular architecture and is based on the principle of measuring the electrical impedance between a number of periodically sensed electrode pairs positioned around the subject's head. The whole setup is controlled by a host computer that performs several functions, such as real-time acquisition, analysis, display and data logging. Two operating options can be chosen by the user: a normal mode that allows continuous monitoring and a triggered mode in which the measurement cycle is automatically started by the occurrence of a preset condition in some other circulatory signal, e.g. the permanently available ECG signal. The design is considerably user-friendly and embodies a number of special safety precautions to take account of the peculiar condition of patients, usually newborn infants hospitalized in intensive care units.     

Complex phase tracing method for fringe pattern analysis

We present what we believe to be a novel complex phase tracing method for fringe pattern analysis related to the phase-locked loop idea. The image with deformed complex fringes is analyzed with lexicographic scansion that leads directly to the investigated phase without unwrapping. Robustness of the procedure is ensured by the delay mechanism in the process of calculating the reference value. A numerical model and examples of application of the presented method are given.     

Effects of emergent vegetation on lateral diffusion in wetlands

Constructed wetlands are widely used for a variety of environmental applications, such as wastewater treatment and recharge, and their efficacy is largely determined by the hydrodynamic characteristics of the flow system. An experimental study was carried out to quantify the lateral dispersion of passive substances in shallow zones of a constructed wetland wherein water flows though the interstices of the distributed vegetation. The experimental set up was designed to mimic the Tres Rios constructed wetland located in Phoenix, Arizona. The major emphasis was on the lateral diffusivity K(t) of a shallow zone with randomly distributed vegetation. The results are presented in the context of a simple theoretical model where K(t) is expressed in terms of the diameter of the plant stalk D(v), the characteristic distance between the plants d(v), the flow velocity U and the drag coefficient C(D) as (K(t)/UD(v))(d(v)/D(v))=betaC(D), where beta is a dimensionless constant. Fitting of data to the above model indicate that C(D), in general, is a function of the Reynolds number (Re). The data are also compared with a model proposed by Nepf et al. (Water Res 35 (1999) 479).     

Free radical polymerization in multilaminated microreactors: 2D and 3D multiphysics CFD modeling

This paper investigates the modeling of styrene free radical polymerization in two different types of microreactor. A multiphysics model which simultaneously takes into account the hydrodynamics, thermal and mass transfer (convection, diffusion and chemical reaction) is proposed. The set of partial differential equations resulting from the model is solved with the help of the finite elements method either in a 2D or a 3D approach. The different modeled microreactors are on one hand an interdigital multilamination microreactor with a large focusing section, and on the other hand a simple T-junction followed by a straight tube with three different radii. The results are expressed in terms of reactor temperature, polydispersity index, number-average degree of polymerization and monomer conversion for different values of the chemical species diffusion coefficient. It was found that the 2D approach gives the same results as the 3D approach but allows to dramatically reduce the computing time. Despite the heat released by the polymerization reaction, it was found that the thermal transfer in such microfluidic devices is high enough to ensure isothermal conditions. Concerning the polydispersity index, the range of diffusion coefficients over which the polydispersity index can be maintained close to the theoretical value for ideal conditions increases as the tube reactor radius decreases. The interdigital multilamination microreactor was found to act as a tubular reactor of 0.78 mm ID but with a shorter length. This underlines that the use of microfluidic devices can lead to a better control of polymerization reactions.     

Amnestic mild cognitive impairment: Difference of memory profile in subjects who converted or did not convert to Alzheimer's disease.

Episodic long-term, short-term, and implicit memory were investigated in 79 elderly subjects who fulfilled criteria for the amnestic form of mild cognitive impairment (a-MCI; i.e., by having an idiopathic amnestic disorder with absence of impairment in cognitive areas other than memory and without confounding medical or psychiatric conditions) and who developed Alzheimer's disease (AD) after 2 years as well as in 111 subjects affected by a-MCI who did not develop dementia. Results document a memory profile in a-MCI subjects characterized by preserved short-term and implicit memory and extensive impairment of episodic long-term memory. In virtually all episodic memory indexes examined (learning, forgetting, recognition abilities), a-MCI subjects who converted to AD were more severely impaired than were subjects who did not become demented. This memory profile, which closely resembles that exhibited by amnestic patients with bilateral mesial-temporal lobe lesions, confirms a precocious phase in preclinical AD characterized by selective involvement of mesial-temporal areas and worsening of the memory impairment as atrophic changes progress in hippocampal structures. In this context of pervasive episodic memory impairment, tests assessing the free recall of verbal material following a delay interval demonstrated the greater sensitivity to memory deficits of a-MCI subjects who developed AD. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Antennas and Propagation for On-Body Communication Systems

On-body communication channels are of increasing interest for a number of applications, such as medical-sensor networks, emergency-service workers, and personal communications. This paper describes investigations into channel characterization and antenna performance at 2.45 GHz. It is shown that significant channel fading occurs during normal activity, due primarily to the dynamic nature of the human body, but also due to multipath around the body and from scattering by the environment. This fading can be mitigated by the use of antenna diversity, and gains of up to 10 dB are obtained. Separation of the antenna's performance from the channel characteristics is difficult, but results show that for many channels, an antenna polarized normal to the body's surface gives the best path gain. Simulation and modeling present many challenges, particularly in terms of the problem's scale, and the need for accurate modeling of the body and its movement.     

An exploration of social networking site use,multitasking, and academic performance among United States and European university students

Studies have shown that multitasking with technology, specifically using Social Networking Sites (SNSs), decreases both efficiency and productivity in an academic setting. This study investigates multitasking’s impact on the relationship between SNS use and Grade Point Average (GPA) in United States (US; n = 451) and European (n = 406) university students using quantitative and qualitative data analysis. Moderated Multiple Regression analysis results showed that the negative relationship between SNS use and GPA was moderated by multitasking only in the US sample. This may be due to European students being less prone to “disruptive” multitasking. The results provide valuable cautionary information about the impact of multitasking and using SNSs in a learning environment on university students’ GPAs.     

Effect of fluoride varnish with added casein phosphopeptide-amorphous calcium phosphate on bond strength to enamel

To investigate the effect of fluoride varnish with added casein phosphopeptide-amorphous calcium phosphate on the shear bond strength (SBS) of two adhesive systems to enamel. Specimens obtained from permanent teeth were randomly distributed among four groups for enamel pretreatment [Control (no treatment, CNT), Duraphat varnish (DV), Clinpro White varnish (CWV), MI Varnish (MIV)], and each group was further divided into two subgroups according to adhesive [Etch&rinse (Adper Single Bond, ASB), self-etch (Clearfil SE Bond, CSE)]. Specimens were stored in distilled water at 37 °C for 24 h. Cylindrical composite specimens (2.3 mm in diameter, 3.0 mm in height) were then bonded to the enamel surfaces. SBS tests were performed and data were analyzed with two-way ANOVA and Tukey’s tests. For both CSE and ASB, SBS values of the CNT groups were significantly higher than those of all the enamel pretreatment groups (p < 0.05). Among the enamel pretreatment groups, SBS values with both adhesive systems were lowest in the MIV groups, followed by CWV and DV groups. In conclusion, pretreatment of enamel surfaces with fluoride-containing varnishes reduced bonding performance of adhesive systems to enamel. MIV appeared to cause greater enamel surface alterations and precipitation, which interfered with adhesive bonding mechanisms.