Enhancement of second-harmonic generation in nonlinear nanolaminate metamaterials by nanophotonic resonances

Nanolaminate metamaterials recently attracted a lot of attention as a novel second-order nonlinear material that can be used in integrated photonic circuits. Here, we explore theoretically and numerically the opportunity to enhance the nonlinear response from such nanolaminates by exploiting Fano resonances supported in grating-coupled waveguides. The enhancement factor of the radiated second harmonic signal compared to a flat nanolaminate can reach values as large as 35 for gold gratings and even 7000 for MgF2 gratings. For the MgF2 grating, extremely high-Q Fano resonances are excited in such all-dielectric system that result in strong local fields in the nonlinear waveguide layer to boost the nonlinear conversion. A significant portion of the nonlinear signal is also strongly coupled to a dark waveguide mode, which remains guided in the nanolaminate. The strong excitation of a dark mode at the second harmonic frequency provides a viable method for utilizing second-order nonlinearities for light generation and manipulation in integrated photonic circuits

Postnatal depression across countries and cultures : a qualitative study

Background: Postnatal depression seems to be a universal condition with similar rates in different countries. However, anthropologists question the cross-cultural equivalence of depression, particularly at a life stage so influenced by cultural factors. Aims: To develop a qualitative method to explore whether postnatal depression is universally recognised, attributed and described and to enquire into people’s perceptions of remedies and services for morbid states of unhappiness within the context of local services. Method: The study took place in 15 centres in 11 countries and drew on three groups of informants: focus groups with new mothers, interviews with fathers and grandmothers, and interviews with health professionals.Textual analysis of these three groups was conducted separately in each centre and emergent themes compared across centres. Results: All centres described morbid unhappiness after childbirth comparable to postnatal depression but not all saw this as an illness remediable by health interventions. Conclusions: Although the findings of this study support the universality of a morbid state of unhappiness following childbirth, they also support concerns about the cross-cultural equivalence of postnatal depression as an illness requiring the intervention of health professionals; this has implications for future research

Fatigue Crack Growth Mechanisms At the Microstructure Scale in Al-Si-Mg Cast Alloys: Mechanisms in Regions II and III

The fatigue crack growth behavior in Regions 11 and III of crack growth was investigated for hypoeutectic and eutectic Al-Si-Mg cast alloys. To isolate and establish the mechanistic contributions of characteristic microstructural features (dendritic α-Al matrix, eutectic phases, Mg-Si strengthening precipitates), alloys with various Si content/morphology, grain size level, and matrix strength were studied; the effect of secondary dendrite arm spacing (SDAS) was also assessed. In Regions 11 and III of crack growth, the observed changes in the fracture surface appearance were associated with changes in crack growth mechanisms at the microstructural scale (from a linear advance predominantly through primary α-Al to a tortuous advance exclusively through AI-Si eutectic Regions). The extent of the plastic zone ahead of the crack tip was successfully used to explain the changes in growth mechanisms. The fatigue crack growth tests were conducted on compact tension specimens under constant stress ratio, R = 0.1, in ambient conditions

PRISM (Program of Resources, Information and Support for Mothers) Protocol for a community-randomised trial [ISRCTN03464021]

BACKGROUND: In the year after birth one in six women has a depressive illness, and 30% are still depressed, or depressed again, when their child is 2 years old, 94% experience at least one major health problem (e.g. back pain, perineal pain, mastitis, urinary or faecal incontinence), 26% experience sexual problems and almost 20% have relationship problems with partners. Women with depression report less practical and emotional support from partners, less social support overall, more negative life events, and poorer physical health. Their perceptions of factors contributing to depression are lack of support, isolation, exhaustion and physical health problems. Fewer than one in three affected women seek help in primary care despite frequent contacts. METHODS/DESIGN: PRISM aims to reduce depression and physical health problems of recent mothers through primary care strategies to increase practitioners' response to these issues, and through community-based strategies to develop broader family and community supports for recent mothers. Eligible local governments will be recruited and randomised to intervention or comparison arms, after stratification (urban/rural, size, birth numbers, extent of community activity), avoiding contiguous boundaries. Maternal depression and physical health will be measured six months after birth, in a one year cohort of mothers, in intervention and comparison communities. The sample size to detect a 20% relative reduction in depression, adjusting for cluster sampling, and estimating a population response fraction of 67% is 5740 × 2. Analysis of the physical and mental health outcomes, by intention to treat, will adjust for the correlated structure of the data

Brief psychological therapies for anxiety and depression in primary care: meta-analysis and meta-regression

Psychological therapies provided in primary care are usually briefer than in secondary care. There has been no recent comprehensive review comparing their effectiveness for common mental health problems. We aimed to compare the effectiveness of different types of brief psychological therapy administered within primary care across and between anxiety, depressive and mixed disorders

Perceptions of postnatal depression across countries and cultures: from a TransCultural Study of PostNatal Depression (TCS-PND)

Objectives The qualitative study was conducted within the international “Transcultural study of postnatal depression (PND)” in 17 centres located in 13 different countries. The aim was to explore perceptions of PND by lay and professional key informants, specifically regarding description of symptoms, awareness of this pathology and of possible care. Methods Broad areas of inquiry and open-ended probes were developed by the TCS-PND research group during international workshops to obtain data comparable between countries on perceptions of PND. A non-random convenience sampling method was used to recruit postpartum mothers for focus groups, and fathers and grandmothers for interviews. Influential healthcare planners and clinicians were interviewed as professional key informants in each centre. Within sites, transcripts of focus groups and interviews underwent a process of text analysis in the original language until exhaustive theme extraction was achieved. Themes (in English) from all the centres were combined into broader categories and after consensus discussions these categories were revalidated. Results and discussion Qualitative data were supplemented in each centre with sociodemographic data to address the issues of: (i) whether perceptions of PND are related to some specific cultural perception of mental heath and/or of status of parenthood and (ii) how high or low levels of general care and specificity of health policy relate to differences in perception of needs for care. Data collected using the same probes and methodology in different countries and cultures has enabled a comparative analysis of perceptions of PND. In addition it has shown that, although not described with the same words, PND is a well-recognised condition by recent mothers in all countries in this study. Data on focus groups and interviews from selected countries are given in the following abstracts to illustrate some similarities and differences in perceptions between countries

Are Politically Connected Firms Turtles or Gazelles? Evidence from the Egyptian Uprising

Using an original firm-level dataset and utilizing the incidence of the Egyptian uprising of 2011, this paper provides an empirical investigation of the effects of firms' political connections on employment growth in Egypt. We use the differences in differences (DiD) framework to compare employment growth in both politically connected firms (PCFs) and their unconnected counterparts before and after the Egyptian uprising. To minimize possible bias in the DiD estimation due to dealing with a heterogeneous group of firms, we apply the propensity score matching (PSM). We find that politically connected firms have decreased their job creation after the uprising