Patterns and determinants of care seeking for obstetric complications in rural northwest Bangladesh: analysis from a prospective cohort study.

BACKGROUND: In communities with low rates of institutional delivery, little data exist on care-seeking behavior for potentially life-threatening obstetric complications. In this analysis, we sought to describe care-seeking patterns for self-reported complications and near misses in rural Bangladesh and to identify factors associated with care seeking for these conditions. METHODS: Utilizing data from a community-randomized controlled trial enrolling 42,214 pregnant women between 2007 and 2011, we used multivariable multinomial logistic regression to explore the association of demographic and socioeconomic factors, perceived need, and service availability with care seeking for obstetric complications or near misses. We also used multivariable multinomial logistic regression to analyze the factors associated with care seeking by type of obstetric complication (eclampsia, sepsis, hemorrhage, and obstructed labor). RESULTS: Out of 9,576 women with data on care seeking for obstetric complications, 77% sought any care, with 29% (n = 2,150) visiting at least one formal provider and 70% (n = 5,149) visiting informal providers only. The proportion of women seeking at least one formal provider was highest among women reporting eclampsia (57%), followed by hemorrhage (28%), obstructed labor (22%), and sepsis (17%) (p < 0.001). In multivariable analyses, socioeconomic factors such as living in a household from the highest wealth quartile (Relative Risk Ratio of 1.49; 95% CI of [1.33-1.73]), women's literacy (RRR of 1.21; 95% CI of [1.05-1.42]), and women's employment (RRR of 1.10; 95% CI of [1.01-1.18]) were significantly associated with care seeking from formal providers. Service factors including living less than 10 kilometers from a health facility (RRR of 1.16; 95% CI of [1.05-1.28]) and facility availability of comprehensive obstetric services (RRR of 1.25; 95% CI of 1.04-1.36) were also significantly associated with seeking care from formal providers. CONCLUSIONS: While the majority of women reporting obstetric complications sought care, less than a third visited health facilities. Improvements in socioeconomic factors such as maternal literacy, coupled with improved geographic access and service availability, may increase care seeking from formal facilities. Enhancing community awareness on symptoms of hemorrhage, sepsis, and obstructed labor and their consequences may promote care seeking for obstetric complications in rural Bangladesh. TRIAL REGISTRATION NUMBER: NCT00860470 .

Real-time tracking of neighborhood surroundings and mood in urban drug misusers: application of a new method to study behavior in its geographical context.

BACKGROUND: Maladaptive behaviors may be more fully understood and efficiently prevented by ambulatory tools that assess people's ongoing experience in the context of their environment. METHODS: To demonstrate new field-deployable methods for assessing mood and behavior as a function of neighborhood surroundings (geographical momentary assessment; GMA), we collected time-stamped GPS data and ecological momentary assessment (EMA) ratings of mood, stress, and drug craving over 16 weeks at randomly prompted times during the waking hours of opioid-dependent polydrug users receiving methadone maintenance. Locations of EMA entries and participants' travel tracks calculated for the 12 before each EMA entry were mapped. Associations between subjective ratings and objective environmental ratings were evaluated at the whole neighborhood and 12-h track levels. RESULTS: Participants (N=27) were compliant with GMA data collection; 3711 randomly prompted EMA entries were matched to specific locations. At the neighborhood level, physical disorder was negatively correlated with negative mood, stress, and heroin and cocaine craving (ps<.0001-.0335); drug activity was negatively correlated with stress, heroin and cocaine craving (ps .0009-.0134). Similar relationships were found for the environments around respondents' tracks in the 12h preceding EMA entries. CONCLUSIONS: The results support the feasibility of GMA. The relationships between neighborhood characteristics and participants' reports were counterintuitive and counter-hypothesized, and challenge some assumptions about how ostensibly stressful environments are associated with lived experience and how such environments ultimately impair health. GMA methodology may have applications for development of individual- or neighborhood-level interventions.

Infrared near-field spectroscopy of trace explosives using an external cavity quantum cascade laser.

Utilizing a broadly-tunable external cavity quantum cascade laser for scattering-type scanning near-field optical microscopy (s-SNOM), we measure infrared spectra of particles of explosives by probing characteristic nitro-group resonances in the 7.1-7.9 µm wavelength range. Measurements are presented with spectral resolution of 0.25 cm(-1), spatial resolution of 25 nm, sensitivity better than 100 attomoles, and at a rapid acquisition time of 90 s per spectrum. We demonstrate high reproducibility of the acquired s-SNOM spectra with very high signal-to-noise ratios and relative noise of <0.02 in self-homodyne detection.

Pushing the Sample-Size Limit of Infrared Vibrational Nanospectroscopy: From Monolayer toward Single Molecule Sensitivity.

While scattering-scanning near-field optical microscopy (s-SNOM) has demonstrated its potential to extend infrared (IR) spectroscopy into the nanometer scale, it has not yet reached its full potential in terms of spectroscopic sensitivity. We combine broadband femtosecond mid-IR excitation with an optimized spectral irradiance of ∼2 W/cm(2)/ cm(-1) (power/area/bandwidth) and a combination of tip- and substrate enhancement to demonstrate single-monolayer sensitivity with exceptional signal-to-noise ratio. Using interferometric time domain detection, the near-field IR s-SNOM spectral phase directly reflects the molecular vibrational resonances and their intrinsic line shapes. We probe the stretching resonance of ∼1000 carbonyl groups at 1700 cm(-1) in a self-assembled monolayer of 16-mercaptohexadecanoic acid (MHDA) on an evaporated gold substrate with spectroscopic contrast and sensitivity of ≲100 vibrational oscillators. From these results we provide a roadmap for achieving true single-molecule IR vibrational spectroscopy in s-SNOM by implementing optical antenna resonant enhancement, increased spectral pump power, and improved detection schemes.

Second-harmonic generation in conjugated polymer films: A sensitive probe of how bulk polymer crystallinity changes with spin speed.

In this paper, we examine the second-harmonic generation (SHG) from spin-cast films of the conjugated polymer poly(2-methoxy-5-(2(')-ethylhexyloxy)para-phenylenevinylene) (MEH-PPV). We find that the SHG intensity depends strongly on the speed used to spin cast the films. Two-dimensional grazing incidence x-ray diffraction (XRD) experiments show that the bulk crystallinity of the MEH-PPV films varies in the same way with spin speed as the SHG intensity. This strongly suggests that instead of being interface specific, the second-harmonic signal from conjugated polymer films is dominated by the crystalline domains in the bulk. The nonmonotonic dependence of both the SHG intensity and the degree of MEH-PPV crystallinity results from a competition between the shear forces and the solvent evaporation rate during spin coating, which produces a maximum degree of crystallinity for MEH-PPV films spin cast at around 1400 rpm. We also use XRD to show that thermal annealing produces MEH-PPV films with a single degree of bulk crystallinity, independent of how they were originally cast. This allows us to model the angle- and thickness-dependent SHG from annealed MEH-PPV films with a single polarizability tensor. We find that the SHG from MEH-PPV films fits best to a bulk-allowed electric quadrupole mechanism, consistent with the bulk SHG seen in other pi-stacked aromatic molecules. Thus, rather than providing information about conjugated polymer interfaces, SHG can be used as a sensitive probe of the local degree of crystallinity in the bulk of conjugated polymer films.

Controlling optical gain in semiconducting polymers with nanoscale chain positioning and alignment.

We control the chain conformation of a semiconducting polymer by encapsulating it within the aligned nanopores of a silica host. The confinement leads to polarized, low-threshold amplified spontaneous emission from the polymer chains. The polymer enters the porous silica film from only one face and the filling of the pores is therefore graded. As a result, the profile of the index of refraction in the film is also graded, in the direction normal to the pores, so that the composite film forms a low-loss, graded-index waveguide. The aligned polymer chains plus naturally formed waveguide are ideally configured for optical gain, with a threshold for amplified spontaneous emission that is twenty times lower than in comparable unoriented polymer films. Moreover, the optimal conditions for ASE are met in only one spatial orientation and with one polarization. The results show that nanometre-scale control of semiconducting polymer chain orientation and position leads to novel and desirable optical properties.