Rank and k-nullity of contact manifolds

We prove that the dimension of the 1-nullity distribution N(1) on a closed Sasakian manifold M of rankl is at least equal to 2l−1 provided that M has an isolated closed characteristic. The result is then used to provide some examples of k-contact manifolds which are not Sasakian. On a closed, 2n+1-dimensional Sasakian manifold of positive bisectional curvature, we show that either the dimension of N(1) is less than or equal to n+1 or N(1) is the entire tangent bundle TM. In the latter case, the Sasakian manifold Mis isometric to a quotient of the Euclidean sphere under a finite group of isometries. We also point out some interactions between k-nullity, Weinstein conjecture, and minimal unit vector fields.

Immersions of almost parallizable

An almost parallelizable n-manifold M can be immersed in Euclidean q-space if 2q>3n.

In vitro and in vivo delivery of the secretagogue diadenosine tetraphosphate from conventional and silicone hydrogel soft contact lenses

Purpose To evaluate the possible use of soft contact lenses (CL) to improve the secretagogue role of diadenosine tetraphosphate (Ap4A) promoting tear secretion. Methods Two conventional hydrogel CL (Omafilcon A and Ocufilcon D) and two silicone hydrogel (SiH) CL (Comfilcon A and Balafilcon A) were used. Ap4A was loaded into the lenses by soaking in a 1 mM Ap4A solution during 12 h. In vitro experiments were performed by placing the lenses in multi-wells during 2 h containing 1 ml of ultrapure water. 100 μl aliquots were taken at time zero and every minute for the first 10 min, and then every 15 min. In vivo experiments were performed in New Zealand rabbits and both the dinucleotide release from SiH and tear secretion were measured by means of Schirmer strips and high-pressure liquid chromatography (HPLC) analysis. Results Ap4A in vitro release experiments in hydrogel CL presented a release time 50 (RT50) of 3.9 ± 0.2 min and 3.1 ± 0.1 min for the non-ionic and the ionic CL, respectively. SiH CL released also Ap4A with RT50 values of 5.1 ± 0.1 min for the non-ionic and 2.7 ± 0.1 min for the ionic CL. In vivo experiments with SiH CL showed RT50 values of 9.3 ± 0.2 min and 8.5 ± 0.2 min for the non-ionic and the ionic respectively. The non-ionic lens Ap4A release was able to induce tear secretion above baseline tear levels for almost 360 min. Conclusion The delivery of Ap4A is slower and the effect lasts longer with non-ionic lenses than ionic lenses.

Electrical characterization of the rectifying contact between aluminium and electrodeposited poly(3-methylthiophene)

A detailed investigation both of the DC and of the AC electrical properties of the Schottky barrier formed between aluminium and electrodeposited poly(3-methylthiophene) is reported. The devices show rectification ratios up to 2 x 10(4) which can be increased further after post-metal annealing. The reverse characteristics of the devices follow predictions based on the image-force lowering of the Schottky barrier, from which the doping density can be estimated, As the forward voltage increases, the device current is limited by the bulk resistance of the polymer with some evidence for injection limitation at the gold counter-electrode at high bias. In the bulk-limited regime, the device current is thermally activated near room temperature with an activation energy in the range 0.2-0.3 eV. Below about 150 K the device current is almost independent of temperature. Capacitance-voltage plots obtained at frequencies well below the device relaxation frequency indicate the presence of two distinct acceptor states, A set of shallow acceptor states are active in forward bias and are believed to determine the bulk conductivity of the polymer. A set of deeper accepters are active only for very small forward voltages and for all reverse voltages, namely when band banding causes the Fermi energy to cross these states. The density of these deeper states is approximately an order of magnitude greater than that of the shallow states. Evidence is presented also for the influence of fabrication conditions on the formation of an insulating interfacial layer at the rectifying interface. The presence of such a layer leads to inversion at the polymer surface and a modification of the I-V characteristics.

Electrical characterization of the rectifying contact between aluminium and electrodeposited poly(3-methylthiophene)

A detailed investigation both of the DC and of the AC electrical properties of the Schottky barrier formed between aluminium and electrodeposited poly(3-methylthiophene) is reported. The devices show rectification ratios up to 2 x 10(4) which can be increased further after post-metal annealing. The reverse characteristics of the devices follow predictions based on the image-force lowering of the Schottky barrier, from which the doping density can be estimated, As the forward voltage increases, the device current is limited by the bulk resistance of the polymer with some evidence for injection limitation at the gold counter-electrode at high bias. In the bulk-limited regime, the device current is thermally activated near room temperature with an activation energy in the range 0.2-0.3 eV. Below about 150 K the device current is almost independent of temperature. Capacitance-voltage plots obtained at frequencies well below the device relaxation frequency indicate the presence of two distinct acceptor states, A set of shallow acceptor states are active in forward bias and are believed to determine the bulk conductivity of the polymer. A set of deeper accepters are active only for very small forward voltages and for all reverse voltages, namely when band banding causes the Fermi energy to cross these states. The density of these deeper states is approximately an order of magnitude greater than that of the shallow states. Evidence is presented also for the influence of fabrication conditions on the formation of an insulating interfacial layer at the rectifying interface. The presence of such a layer leads to inversion at the polymer surface and a modification of the I-V characteristics.

International contact lens prescribing in 2015 : our 15th annual report in CLS provides information about 23,000 fits in 34 markets

We have been collecting data on worldwide contact lens prescribing habits for almost 20 years. Over this time period, we have amassed prospective information about 315,000 contact lens fits in 59 countries. This article marks our 15th report in Contact Lens Spectrum and features a breakdown of more than 23,000 contact lens fits in 34 markets.As in previous years, our international network of coordinators distributed survey forms to eyecare practitioners in their market who then recorded generic information about the first 10 patients fit with contact lenses after receipt. Information is gathered about patient age and gender; whether the contact lenses are prescribed as a new fit or a refit; contact lens material, design, and replacement frequency; number of intended days per week of use; wearing modality; and care system. Contact lens fits are weighted to reflect the number of fits undertaken by each eyecare practitioner. The study data were entered and processed at the University of Manchester and at the University of Waterloo.

An investigation of contact transmission of methicillin-resistant staphylococcus aureus

Hand hygiene is critical in the healthcare setting and it is believed that methicillin-resistant Staphylococcus aureus (MRSA), for example, is transmitted from patient to patient largely via the hands of health professionals. A study has been carried out at a large teaching hospital to estimate how often the gloves of a healthcare worker are contaminated with MRSA after contact with a colonized patient. The effectiveness of handwashing procedures to decontaminate the health professionals' hands was also investigated, together with how well different healthcare professional groups complied with handwashing procedures. The study showed that about 17% (9–25%) of contacts between a healthcare worker and a MRSA-colonized patient results in transmission of MRSA from a patient to the gloves of a healthcare worker. Different health professional groups have different rates of compliance with infection control procedures. Non-contact staff (cleaners, food services) had the shortest handwashing times. In this study, glove use compliance rates were 75% or above in all healthcare worker groups except doctors whose compliance was only 27%.

Computational power meets human contact

This chapter traces the development of the global digital storytelling movement from its origins in California to its adoption by the BBC in the UK and its subsequent dispersal around the world. It identifies the foundational practices, uneven development and diffusion, and emergent practices internationally.

Modelling the effects of bone fragment contact in fracture healing

The fracture healing process is modulated by the mechanical environment created by imposed loads and motion between the bone fragments. Contact between the fragments obviously results in a significantly different stress and strain environment to a uniform fracture gap containing only soft tissue (e.g. haematoma). The assumption of the latter in existing computational models of the healing process will hence exaggerate the inter-fragmentary strain in many clinically-relevant cases. To address this issue, we introduce the concept of a contact zone that represents a variable degree of contact between cortices by the relative proportions of bone and soft tissue present. This is introduced as an initial condition in a two-dimensional iterative finite element model of a healing tibial fracture, in which material properties are defined by the volume fractions of each tissue present. The algorithm governing the formation of cartilage and bone in the fracture callus uses fuzzy logic rules based on strain energy density resulting from axial compression. The model predicts that increasing the degree of initial bone contact reduces the amount of callus formed (periosteal callus thickness 3.1mm without contact, down to 0.5mm with 10% bone in contact zone). This is consistent with the greater effective stiffness in the contact zone and hence, a smaller inter-fragmentary strain. These results demonstrate that the contact zone strategy reasonably simulates the differences in the healing sequence resulting from the closeness of reduction.