Profiling in wildlife crime : recovery of human DNA deposited outside

Incidents of bird of prey persecution receive a lot of media coverage in the UK, with investigations rarely recovering sufficient evidence to proceed to prosecution. One of the main challenges is to identify a suspect, as these offences are carried out in remote locations without witnesses, and crime scenes may not be found for days. However, traps, poisoned baits and bird of prey carcasses can be recovered from these crime scenes. This study aimed to determine whether reportable human DNA profiles could be recovered from any of these substrates after periods of time outside. Experiments depositing human touch DNA on duplicate substrates (traps, rabbit baits and corvid carcasses) set for 0, 1, 2, 4, 7 and 10 days outside were carried out, with DNA recovery and profiling following standard operating procedures for Scottish Police Authority Forensic Services. Weather conditions varied among experiments, including some heavy rainfall. Results demonstrated that it was possible to obtain reportable DNA profiles from all substrates after at least 1 day outside. Most promisingly, the traps showed no drop-off in DNA persistence over the experiments as complete DNA profiles were obtained after the full 10 days outside. A further experiment using 4 bird of prey carcasses confirmed that it is possible to obtain reportable human DNA profiles from them after 1 day outside (n = 2 reportable profiles). These results show that touch DNA can persist in an outdoor environment, and provide a tantalising avenue for inquiry in bird of prey persecution investigations

The surface wave environment in the GATE B/C Scale - Phase III

The surface wave environment in the GATE B/C scale is described from wave measurements made from buoys and aircraft during Phase III (September 1974). Particular emphasis is given to the wave measurements made from the pitch-roll buoy deployed in the B-scale array from the ship Gilliss and a similar buoy deployed in the C-scale array from Quadra. Reduction of the pitch-roll buoy measurements provided estimates of the one-dimensional wave spectrum as well as of the mean direction and spread of wave energy as a function of frequency. The data clearly revealed the importance of external forcing on the wave climate in GATE. Most of the wave energy present in the GATE areas was found to be swell imported from the trade wind circulations of both hemispheres and from an intense extratropical cyclone which crossed the North Atlantic at high latitudes early in Phase III. Locally generated waves were clearly evident in the wave spectra, but their energy level way have been modulated significantly by the low-frequency swell. The GATE wave data set can provide a powerful test of contemporary numerical wave-prediction models. The present study defines the, attributes which are required of such models for meaningful application to the GATE needs

Coarse-grained model of entropic allostery

Many signaling functions in molecular biology require proteins to bind to substrates such as DNA in response to environmental signals such as the simultaneous binding to a small molecule. Examples are repressor proteins which may transmit information via a conformational change in response to the ligand binding. An alternative entropic mechanism of "allostery" suggests that the inducer ligand changes the intramolecular vibrational entropy, not just the mean static structure. We present a quantitative, coarse-grained model of entropic allostery, which suggests design rules for internal cohesive potentials in proteins employing this effect. It also addresses the issue of how the signal information to bind or unbind is transmitted through the protein. The model may be applicable to a wide range of repressors and also to signaling in trans-membrane proteins

Kramers rate theory of ionization and dissociation of bound states

Calculating the microscopic dissociation rate of a bound state, such as a classical diatomic molecule, has been difficult so far. The problem was that standard theories require an energy barrier over which the bound particle (or state) escapes into the preferred low-energy state. This is not the case when the long-range repulsion responsible for the barrier is either absent or screened (as in Cooper pairs, ionized plasma, or biomolecular complexes). We solve this classical problem by accounting for entropic memory at the microscopic level. The theory predicts dissociation rates for arbitrary potentials and is successfully tested on the example of plasma, where it yields an estimate of ionization in the core of Sun in excellent agreement with experiments. In biology, the new theory accounts for crowding in receptor-ligand kinetics and protein aggregation

High and low molecular weight crossovers in the longest relaxation time dependence of linear cis-1,4 polyisoprene by dielectric relaxations

The dielectric relaxation of cis-1,4 Polyisoprene [PI] is sensitive not only to the local and segmental dynamics but also to the larger scale chain (end-to-end) fluctuations. We have performed a careful dielectric investigation on linear PI with various molecular weights in the range of 1 to 320 kg/mol. The broadband dielectric spectra of all samples were measured isothermally at the same temperature to avoid utilizing shift factors. For the low and medium molecular weight range, the comparisons were performed at 250 K to access both the segmental relaxation and normal mode peaks inside the available frequency window (1 mHz–10 MHz). In this way, we were able to observe simultaneously the effect of molecular mass on the segmental dynamics—related with the glass transition process—and on the end-to-end relaxation time of PI and thus decouple the direct effect of molecular weight on the normal mode from that due to the effect on the monomeric friction coefficient. The latter effect is significant for low molecular weight (M w < 33 kg/mol), i.e., in the range where the crossover from Rouse dynamics to entanglement limited flow occurs. Despite the conductivity contribution at low frequency, careful experiments allowed us to access to the normal mode signal for molecular weights as high as M w = 320 kg/mol, i.e., into the range of high molecular weights where the pure reptation behavior could be valid, at least for the description of the slowest chain modes. The comparison between the dielectric relaxations of PI samples with medium and high molecular weight was performed at 320 K. We found two crossovers in the molecular weight dependence of the longest relaxation time, the first around a molecular weight of 6.5 ± 0.5 kg/mol corresponding to the end of the Rouse regime and the second around 75 ± 10 kg/mol. Above this latter value, we find a power law compatible with exponent 3 as predicted by the De Gennes theory