Obtaining data linkage consent for children: factors influencing outcomes and potential biases

Understanding factors associated with consent for data linkage has largely focussed on adults, but parents or guardians can also be asked to consent on behalf of children for whom they are responsible. A framework for consent decision is presented, and is tested using a large nationally representative survey asking mothers to consent for both themselves and their children for two sets of records. Nearly all mothers give the same consent outcome for all their children. Consent rates are higher for education records than for health records and higher for mothers than children. Multivariate analyses suggest that minorities are generally less likely to consent, while more trust increases chances of consent. Several survey environment factors are important, with harder-to-contact respondents less likely to consent, while the presence of others and higher interviewer-respondent rapport lead to a higher chance of consent. These findings suggest potential methodologies to improve consent rates and possibly minimise bias. This is important given significant demographic differences between children across consent outcomes. However, data from a survey of 10?15 year olds in the study shows fewer differences for several important behaviours and attitudes across consent outcomes

Optical properties of CDOM across the Polar Front in the Barents Sea:Origin, distribution and significance

Colored Dissolved Organic Matter (CDOM) is an important optical constituent in seawater, which significantly attenuates the violet to blue portion of visible light. Thus, CDOM reduces the radiation energy available to phytoplankton and affects remote-sensing signals. We present data from two cruises transecting the Polar Front from Atlantic to Arctic waters in the Barents Sea, in 2007 and 2008. The latter took place during the spring bloom of phytoplankton in May (0.2&lt;[Chl a]&lt;13mgm -3) and the former during August (max. [Chl a]&lt;2mgm -3). Absorption by CDOM at 443nm ranged from 0.004 to 0.080m -1 during May and from 0.006 to 0.162m -1 during August. Surprisingly, CDOM absorption differed little across the Polar Front, but was higher during August than during May (P&lt;0.05). The slope coefficient of the absorption spectra (S) ranged from 0.008 to 0.036nm -1 (mean=0.015nm -1) including both cruises, and varied little across the Front (P&gt;0.05). The CDOM remote sensing product from GlobColour correlated well with sampled data (R 2=0.73) during May. However, during August the satellite product performed poorly (R 2=0.02) due to extensive scattering caused by coccolithophorids in the Atlantic Water. The CDOM pool was of autochthonous (marine) origin as characterized from its S vs. absorption relationship. Modeling showed that CDOM, on average, contributed equally to the light absorption as did phytoplankton (at 1mg Chl a m -3), and thereby reduces the amount of light available for primary production.</p

Propensity to consent to data linkage: experimental evidence on the role of three survey design features in a UK longitudinal panel

When performing data linkage, survey respondents need to provide their informed consent. Since not all respondents agree to this request, the linked data-set will have fewer observations than the survey data-set alone and bias may be introduced. By focusing on the role that survey design features play in gaining respondents’ consent, this paper provides an innovative contribution to the studies in this field. Analysing experimental data collected in a nationally representative household panel survey of the British population, we find that interview features such as question format (dependent/independent questions) and placement of the consent question within the questionnaire have an impact on consent rates

Optical impact of an Emiliania huxleyi bloom in the frontal region of the Barents Sea

The impact on downwelling irradiance of phytoplankton, cromophoric dissolved organic matter (CDOM) and particulate inorganic carbon (PIC) in the form of coccoliths, is described using a radiative transfer model and field data from the Barents Sea (BS). While annual Emiliania huxleyi blooms in the BS have been detected with satellite remote sensing, this is the first bio-optical field study on E. huxleyi from this area. Bio-optical variables were measured in August 2007 along a transect through the Polar Front from Arctic Water (ArW) into an E. huxleyi bloom in Atlantic Water (AW). The depth of the euphotic zone was on average 52m in ArW, 45m in frontal mixed water (FMW) and 21m in AW. At the 10% irradiance depth in AW, phytoplankton had attenuated 40%, CDOM 17% and PIC 18% of the irradiance from 400 to 700nm. Numbers from ArW were 36%, 26% and &lt;1%, respectively. The relative potential for Primary Production (PP pot) in AW was 1.8× higher than in ArW, and PIC had reduced PP pot in AW by 20-40% at stations with ~100-130mg PIC m -3. A novel approach for estimating PIC based on a theoretical relationship between diffuse attenuation and irradiance reflectance is also described.</p

Analysis of four studies in a comparative framework reveals: health linkage consent rates on British cohort studies higher than on UK household panel surveys

Background: A number of cohort studies and longitudinal household panel studies in Great Britain have asked for consent to link survey data to administrative health data. We explore commonalities and differences in the process of collecting consent, achieved consent rates and biases in consent with respect to socio-demographic, socio-economic and health characteristics. We hypothesise that British cohort studies which are rooted within the health sciences achieve higher consent rates than the UK household longitudinal studies which are rooted within the social sciences. By contrast, the lack of a specific health focus in household panel studies means there may be less selectivity in consent, in particular, with respect to health characteristics. Methods: Survey designs and protocols for collecting informed consent to health record linkage on two British cohort studies and two UK household panel studies are systematically compared. Multivariate statistical analysis is then performed on information from one cohort and two household panel studies that share a great deal of the data linkage protocol but vary according to study branding, survey design and study population. Results: We find that consent is higher in the British cohort studies than in the UK household panel studies, and is higher the more health-focused the study is. There are no systematic patterns of consent bias across the studies and where effects exist within a study or study type they tend to be small. Minority ethnic groups will be underrepresented in record linkage studies on the basis of all three studies. Conclusions: Systematic analysis of three studies in a comparative framework suggests that the factors associated with consent are idiosyncratic to the study. Analysis of linked health data is needed to establish whether selectivity in consent means the resulting research databases suffer from any biases that ought to be considered

Security Analysis of the NTRUEncrypt Public Key Encryption Scheme

The public key cryptosystem NTRUEncrypt is analyzed with a main focus on lattice based attacks. We give a brief overview of NTRUEncrypt and the padding scheme NAEP. We propose NTRU-KEM, a key encapsulation method using NTRU, and prove it secure. We briefly cover some non-lattice based attacks but most attention is given to lattice attacks on NTRUEncrypt. Different lattice reduction techniques, alterations to the NTRUEncrypt lattice and breaking times for optimized lattices are studied

Natural iron enrichment around the Antarctic Peninsula in the Southern Ocean

As part of the US-AMLR program in January-February of 2006, 99 stations in the South Shetland Islands-Antarctic Peninsula region were sampled to understand the variability in hydrographic and biological properties related to the abundance and distribution of krill in this area. Concentrations of dissolved iron (DFe) and total acid-leachable iron (TaLFe) were measured in the upper 150 m at 16 of these stations (both coastal and pelagic waters) to better resolve the factors limiting primary production in this area and in downstream waters of the Scotia Sea. The concentrations of DFe and TaLFe in the upper mixed layer (UML) were relatively high in Weddell Sea Shelf Waters (~0.6 nM and 15 nM, respectively) and low in Drake Passage waters (~0.2 nM and 0.9 nM, respectively). In the Bransfield Strait, representing a mixture of waters from the Weddell Sea and the Antarctic Circumpolar Current (ACC), concentrations of DFe were ~0.4 nM and of TaLFe ~1.7 nM. The highest concentrations of DFe and TaLFe in the UML were found at shallow coastal stations close to Livingston Island (~1.6 nM and 100 nM, respectively). The ratio of TaLFe:DFe varied with the distance to land: ~45 at the shallow coastal stations, ~15 in the high-salinity waters of Bransfield Strait, and ~4 in ACC waters. Concentrations of DFe increased slightly with depth in the water column, while that of TaLFe did not show any consistent trend with depth. Our Fe data are discussed in regard to the hydrography and water circulation patterns in the study area, and with the hypothesis that the relatively high rates of primary production in the central regions of the Scotia Sea are partially sustained by natural iron enrichment resulting from a northeasterly flow of iron-rich coastal waters originating in the South Shetland Islands-Antarctic Peninsula region

Organic matter remineralization in marine sediments : A Pan-Arctic synthesis

Natural Environment Research Council (GrantNumber(s): NE/J023094/1; Grant recipient(s): Ursula Witte) ArcticNet (GrantNumber(s): Hotspot biodiversity project; Grant recipient(s): Philippe Archambault)Peer reviewedPublisher PD