The photocurrent response of human cones is fast and monophasic

BACKGROUND: The precise form of the light response of human cone photoreceptors in vivo has not been established with certainty. To investigate the response shape we compare the predictions of a recent model of transduction in primate cone photoreceptors with measurements extracted from human cones using the paired-flash electroretinogram method. As a check, we also compare the predictions with previous single-cell measurements of ground squirrel cone responses. RESULTS: The predictions of the model provide a good description of the measurements, using values of parameters within the range previously determined for primate retina. The dim-flash response peaks in about 20 ms, and flash responses at all intensities are essentially monophasic. Three time constants in the model are extremely short: the two time constants for inactivation (of visual pigment and of transducin/phosphodiesterase) are around 3 and 10 ms, and the time constant for calcium equilibration lies in the same range. CONCLUSION: The close correspondence between experiment and theory, using parameters previously derived for recordings from macaque retina, supports the notion that the electroretinogram approach and the modelling approach both provide an accurate estimate of the cone photoresponse in the living human eye. For reasons that remain unclear, the responses of isolated photoreceptors from the macaque retina, recorded previously using the suction pipette method, are considerably slower than found here, and display biphasic kinetics

Question types, responsiveness and self-contradictions when prosecutors and defense attorneys question alleged victims of child sexual abuse

We examined 120 trial transcripts of 6- to 12-year-old children testifying to sexual abuse. Age and attorney role were analyzed in relation to question types, children’s responsiveness, and self-contradiction frequency. A total of 48,716 question-response pairs were identified. Attorneys used more closed-ended than open-ended prompts. Prosecutors used more invitations (3% vs. 0%), directives and optionposing prompts than defence attorneys, who used more suggestive prompts than prosecutors. Children were more unresponsive to defence attorneys than to prosecutors. Self-contradictions were identified in 95% of the cases. Defence attorneys elicited more self-contradictions than prosecutors, but nearly all prosecutors (86%) elicited at least one self-contradiction. Suggestive questions elicited more selfcontradictions than any other prompt type. There were no associations with age. These findings suggest that neither prosecutors nor defence attorneys question children in developmentally appropriate ways.This is the author accepted manuscript. The final version is available from Wiley via http://dx.doi.org/10.1002/acp.310

Challenging the Credibility of Alleged Victims of Child Sexual Abuse in Scottish Courts.

This study examined the effects of credibility-challenging questions (n = 2,729) on 62 5- to 17-year-olds’ testimony in child sexual abuse cases in Scotland by categorizing the type, source, and content of the credibility-challenging questions defense lawyers asked and assessing how children responded. Credibility-challenging questions comprised 14.9% of all questions asked during cross-examination. Of defense lawyers’ credibility-challenging questions, 77.8% focused generally on children’s honesty, whereas the remainder referred to specific inconsistencies in the children’s testimony. Children resisted credibility challenges 54% of the time, significantly more often than they provided compliant responses (26.8%). The tendency to resist was significantly lower for questions focused on specific rather than general inconsistencies, and peripheral rather than central content. Overall, children resisted credibility challenges more often when the aim and content of the question could be understood easily. As this was a field study, the accuracy of children’s responses could not be assessed. The findings suggest that credibility-challenging questions that place unrealistic demands on children’s memory capacities (e.g., questions focused on peripheral content or highly specific details) occur frequently, and that juries should be made aware of the disproportionate effects of such questioning on the consistency of children’s testimony.This research was supported by an Economic and Social Research Council studentship to Samantha J. Andrews. The research was completed as Ms. Szojka’s undergraduate dissertation at the University of Cambridge

Wind Data Mining by Kohonen Neural Networks

Time series of Circulation Weather Type (CWT), including daily averaged wind direction and vorticity, are self-classified by similarity using Kohonen Neural Networks (KNN). It is shown that KNN is able to map by similarity all 7300 five-day CWT sequences during the period of 1975–94, in London, United Kingdom. It gives, as a first result, the most probable wind sequences preceding each one of the 27 CWT Lamb classes in that period. Inversely, as a second result, the observed diffuse correlation between both five-day CWT sequences and the CWT of the 6(th) day, in the long 20-year period, can be generalized to predict the last from the previous CWT sequence in a different test period, like 1995, as both time series are similar. Although the average prediction error is comparable to that obtained by forecasting standard methods, the KNN approach gives complementary results, as they depend only on an objective classification of observed CWT data, without any model assumption. The 27 CWT of the Lamb Catalogue were coded with binary three-dimensional vectors, pointing to faces, edges and vertex of a “wind-cube,” so that similar CWT vectors were close

Studying Cat (Felis catus) Diabetes: Beware of the Acromegalic Imposter

Naturally occurring diabetes mellitus (DM) is common in domestic cats (Felis catus). It has been proposed as a model for human Type 2 DM given many shared features. Small case studies demonstrate feline DM also occurs as a result of insulin resistance due to a somatotrophinoma. The current study estimates the prevalence of hypersomatotropism or acromegaly in the largest cohort of diabetic cats to date, evaluates clinical presentation and ease of recognition. Diabetic cats were screened for hypersomatotropism using serum total insulin-like growth factor-1 (IGF-1; radioimmunoassay), followed by further evaluation of a subset of cases with suggestive IGF-1 (>1000 ng/ml) through pituitary imaging and/ or histopathology. Clinicians indicated pre-test suspicion for hypersomatotropism. In total 1221 diabetic cats were screened; 319 (26.1%) demonstrated a serum IGF-1>1000 ng/ml (95% confidence interval: 23.6-28.6%). Of these cats a subset of 63 (20%) underwent pituitary imaging and 56/63 (89%) had a pituitary tumour on computed tomography; an additional three on magnetic resonance imaging and one on necropsy. These data suggest a positive predictive value of serum IGF-1 for hypersomatotropism of 95% (95% confidence interval: 90-100%), thus suggesting the overall hypersomatotropism prevalence among UK diabetic cats to be 24.8% (95% confidence interval: 21.2-28.6%). Only 24% of clinicians indicated a strong pre-test suspicion; most hypersomatotropism cats did not display typical phenotypical acromegaly signs. The current data suggest hypersomatotropism screening should be considered when studying diabetic cats and opportunities exist for comparative acromegaly research, especially in light of the many detected communalities with the human disease

The 1983 drought in the West Sahel: a case study

Some drought years over sub-Saharan west Africa (1972, 1977, 1984) have been previously related to a cross-equatorial Atlantic gradient pattern with anomalously warm sea surface temperatures (SSTs) south of 10°N and anomalously cold SSTs north of 10°N. This SST dipole-like pattern was not characteristic of 1983, the third driest summer of the twentieth century in the Sahel. This study presents evidence that the dry conditions that persisted over the west Sahel in 1983 were mainly forced by high Indian Ocean SSTs that were probably remanent from the strong 1982/1983 El Niño event. The synchronous Pacific impact of the 1982/1983 El Niño event on west African rainfall was however, quite weak. Prior studies have mainly suggested that the Indian Ocean SSTs impact the decadal-scale rainfall variability over the west Sahel. This study demonstrates that the Indian Ocean also significantly affects inter-annual rainfall variability over the west Sahel and that it was the main forcing for the drought over the west Sahel in 1983

The effect of bleach duration and age on the ERG photostress test

Background: The ERG photostress test assesses the recovery of the focal 41 Hz ERG following exposure to a bright light that bleaches a significant proportion of photopigment. The aims of this study were: 1) to compare the repeatability of the ERG photostress test recovery time constant following long and short duration light exposure, and 2) to determine the effect of age on the ERG photostress test recovery time constant. Methods: Focal 41 Hz ERGs were recorded from 23 participants (age range 20–71 years) at 20-second intervals for 5 minutes following either a short-duration (photoflash) or long-duration (equilibrium) light exposure. After a 5-minute wash-out period, the procedure was repeated using the second bleach modality. The time constant of cone recovery was determined by fitting an exponential model to the amplitude recovery data. The whole procedure was repeated on a second occasion. The co-efficient of repeatability (CoR) was calculated for each bleaching technique. The relationship between the time constant of recovery and age was investigated (Pearson’s correlation coefficient). Results: The time constant of recovery following an equilibrium bleach was more repeatable than recovery following a photoflash (CoR = 85s and 184s respectively). Eight trials (from seven participants) failed to show a reduction in amplitude following the photoflash, suggesting that a blink or fixation loss had occurred. All participants were reliably light-adapted by the equilibrium bleach. For the equilibrium bleach data, the time constant of recovery increased with age at a rate of 27 seconds per decade. Conclusions: The equilibrium bleach was more reliable and repeatable than the photoflash. Increasing participant age was shown to result in a lengthening of the recovery time constant, of a magnitude comparable to previously published psychophysical data

Wellbeing of gay fathers with children born through surrogacy: a comparison with lesbian-mother families and heterosexual IVF parent families.

STUDY QUESTION: Are there differences in levels of parental wellbeing (parental stress, psychological adjustment and partner relationship satisfaction) between gay-father families with infants born through surrogacy, lesbian-mother families with infants born through donor insemination, and heterosexual-parent families with infants born through IVF? SUMMARY ANSWER: There were no differences in parental wellbeing. WHAT IS KNOWN ALREADY: The only other study of parental wellbeing in gay-father families formed through surrogacy (mean age children: 4 years old) found no difference in couple relationship satisfaction between these families and lesbian-mother families formed through donor insemination and heterosexual-parent families formed without assisted reproductive technologies. STUDY DESIGN, SIZE, DURATION: This cross-sectional study is part of an international research project involving 38 gay-father families, 61 lesbian-mother families and 41 heterosexual-parent families with 4-month-olds. In each country (the UK, the Netherlands and France), participants were recruited through several sources, such as specialist lawyers with expertise in surrogacy (for the recruitment of gay fathers), lesbian and gay parenting support groups, fertility clinics (for the recruitment of lesbian and heterosexual parents), and/or online forums and magazines. PARTICIPANTS/MATERIALS, SETTING, METHODS: During a home visit when their infants were between 3.5 and 4.5 months old, participants completed standardized measures of parental stress, parental psychological adjustment (anxiety and depression) and partner relationship satisfaction. MAIN RESULTS AND THE ROLE OF CHANCE: All parents reported relatively low levels of parental stress, anxiety and depression, and were all relatively satisfied with their intimate relationships. After controlling for caregiver role (primary or secondary caregiver role), there were no significant family type differences in parental stress, P = 0.949, depression, P = 0.089, anxiety, P = 0.117, or relationship satisfaction, P = 0.354. LIMITATIONS, REASONS FOR CAUTION: The findings cannot be generalized to all first-time ART parents with infants because only families from relatively privileged backgrounds participated. WIDER IMPLICATIONS OF THE FINDINGS: Our findings may have implications for the development of policy and legislation in relation to these new family forms, as well as the regulation of surrogacy in the Netherlands and France. In addition, our findings might encourage professional organizations of obstetricians and gynecologists in these countries to recommend that requests for assisted reproduction should be considered regardless of the applicants' sexual orientation. STUDY FUNDING/COMPETING INTEREST(S): This research was supported, under the auspices of the Open Research Area (Application BO 3973/1-1; Principal Investigator, Michael E Lamb), by grants from the UK Economic and Social Research Council (ESRC; Grant ES/K006150/1; Principal Investigator, Michael E. Lamb), The Netherlands Organisation for Scientific Research (NWO; Grant NWO 464-11-001, Principal Investigator, Henny W.M. Bos) and the French Agence Nationale de Recherche (ANR; Grant ANR-12-ORAR-00005-01, Principal Investigator, Olivier Vecho) whose support is gratefully acknowledged. There were no competing interests

Signaling Cascades Modulate the Speed of Signal Propagation through Space

Cells are not mixed bags of signaling molecules. As a consequence, signals must travel from their origin to distal locations. Much is understood about the purely diffusive propagation of signals through space. Many signals, however, propagate via signaling cascades. Here, we show that, depending on their kinetics, cascades speed up or slow down the propagation of signals through space, relative to pure diffusion.We modeled simple cascades operating under different limits of Michaelis-Menten kinetics using deterministic reaction-diffusion equations. Cascades operating far from enzyme saturation speed up signal propagation; the second mobile species moves more quickly than the first through space, on average. The enhanced speed is due to more efficient serial activation of a downstream signaling module (by the signaling molecule immediately upstream in the cascade) at points distal from the signaling origin, compared to locations closer to the source. Conversely, cascades operating under saturated kinetics, which exhibit zero-order ultrasensitivity, can slow down signals, ultimately localizing them to regions around the origin.Signal speed modulation may be a fundamental function of cascades, affecting the ability of signals to penetrate within a cell, to cross-react with other signals, and to activate distant targets. In particular, enhanced speeds provide a way to increase signal penetration into a cell without needing to flood the cell with large numbers of active signaling molecules; conversely, diminished speeds in zero-order ultrasensitive cascades facilitate strong, but localized, signaling