Opportunities and challenges of next-generation DNA sequencing for breast units.

BACKGROUND: The aim of this review is to introduce the topic of next-generation DNA sequencing, a new technology that is being introduced into clinical practice, and to explain the potential impact for breast cancer surgeons and the wider breast cancer multidisciplinary team. METHODS: The PubMed database was used to identify relevant studies relating to breast cancer genetics. This evidence was then used to provide context and background information to demonstrate how next-generation sequencing (NGS) might change breast cancer practice. RESULTS: With NGS, breast cancer clinicians will know whether their patients carry high-risk mutations in genes, such as BRCA1 or BRCA2, before the start of treatment. This could alter treatment decisions; for instance, more women might opt for mastectomy instead of breast-conserving surgery, or for bilateral rather than unilateral surgery. CONCLUSION: The introduction of NGS will have a significant impact on breast cancer services in the near future. Speed of testing will improve in regions of the world where NGS is adopted in place of conventional sequencing, and, as costs decrease, genetic testing will also become accessible and realistic in less well funded health economies. This will create opportunities to improve patient treatment and challenges for the breast cancer multidisciplinary team.

Diverticular disease in younger patients--is it clinically more complicated and related to obesity?

AIM: The aims of this systematic review were to determine the presentations of diverticular disease in patients under 40 years of age and to assess whether obesity is an important factor. METHOD: The PubMed and EMBASE databases and the Cochrane Library were searched to identify all original articles published between 1990 and 2011 on diverticular disease severity in obese patients (body mass index of ≥ 30 kg/m(2) ) under 40 years of age. RESULTS: Twenty-three clinical case series (two of which were prospective) were identified plus two large aetiological population-based studies. These reported that young patients with diverticular disease were presenting more frequently, that diverticular disease in this age group was less likely to be complicated but that emergency operation rates were higher. The majority (63.1-96.5%) of patients under 40 years of age with diverticular disease were obese. CONCLUSION: The studies suggest that in the young, obese patient with lower abdominal pain, diverticulitis and appendicitis are included in the differential diagnosis. CT and/or laparoscopy should be considered where the diagnosis is in doubt.

The use of harmonic analysis of the strain response in Pb(Mg(1/3)Nb(2/3)) O3-based ceramics to calculate electrostrictive coefficients.

The electromechanical response of ceramics has long been described with Landau Devonshire phenomenology, wherein the strain response is linked to a polynomial expansion in electric field or dielectric displacement. Consequently, the electromechanical response has been modeled with a variety of basis functions. However, these models have failed to accommodate hysteresis and the harmonic response that arises with saturation phenomena. In addition, no quantitative criterion has been used to truncate the expansion. By implementing a discrete Fourier transform in conjunction with Devonshire phenomenology, these three problems can be overcome as demonstrated with a dielectrically aged, lead magnesium niobate relaxor ferroelectric well above its Tmax, i.e., operating in the electrostrictive regime.

Electrostrictive ceramics for low-frequency active transducers.

Electrostrictive ceramics based on Pb(Mg(1/3)Nb(2/3 ))O(3) have demonstrated promise as low-frequency active materials. They broaden the range of design options by providing a mix of properties unavailable in traditional piezoceramics. Typical properties are: 1000 microstrain on the interval 0-1 MV/m with a k(33) of 0.5; high-field electrical impedance ~5 times that of traditional piezoelectrics; graceful, predictable, and repeatable property variation with temperature, frequency, and prestress; recoverable change of properties with temperature. Unipolar excitation at fields less than 1 MV/m is typical to provide direct frequency conversion and prevent corona discharge and reliability issues within transducers. Although electrostrictive ceramics are not direct replacements for traditional piezoceramics, they have many similarities in physical and chemical properties. The differences are most obvious in the electromechanical response behavior with changes in bias field, drive level, frequency, and prestress. In addition, the "rules-of-thumb" for traditional piezoceramics, both processing and use, do not wholly apply to electrostrictive ceramics. The development and present state of the art in electrostrictive ceramics for low-frequency uses are detailed.

Determination of nonlinear electromechanical energy conversion and the field-dependent elastic modulus of Pb(Mg(1/3)Nb(2/3 ))O(3)-based electrostrictors.

Energy conversion efficiency is a critical parameter for all electromechanical materials. Although excellent techniques are available for linear materials, nonlinearities complicate the determination of conversion efficiency in electrostrictive Pb(Mg(1/3)Nb(2/3 ))O(3) (PMN). The field dependence of the elastic modulus presents additional problems. A technique combining pulse-echo ultrasound has been developed to approximate the change in the Young's modulus with applied field. A 30% decrease was observed at 1 MV/m (from ~100 to ~70 GPa). The boundary condition for these measurements was a constant electric field as opposed to constant dielectric displacement. In combination with the results from harmonic analysis, the modulus data may be used to determine the electromechanical conversion efficiency. This has been accomplished using an energy balance criterion for a PMN-based composition (with and without dc bias). The resulting longitudinal coupling values are >0.5 for practical electric fields (<1 MV/m peak).

Harmonic analysis of the polarization response in Pb(Mg(1/3 )Nb(2/3))O(3)-based ceramics-A study in aging.

The polarization response of a ferroelectric ceramic displays nonlinear behavior at high applied fields due to saturation effects. Weak-field dielectric aging imposes additional nonlinearity on the hysteresis loops of these materials. Harmonic analysis using a discrete Fourier transform (DFT) permitted an observation of the change in the polarization frequency spectrum as Pb(Mg(1/3)Nb(2/3))O (3)-based relaxor ceramics aged. It also facilitated the calculation of ac current, power, and "internal bias field". The results show that particular harmonics in the polarization signal are sensitive indications of aging behavior. The average power dissipated at weak ac fields was found to decrease with aging time; and the power dissipated at strong fields tended to increase.