Exercise knowledge, barriers and motivators among LRRK2 G2019S mutation carriers.

INTRODUCTION: People with a Gly2019Ser mutation in the leucine-rich repeat kinase 2 (LRRK2 G2019S) are at increased risk of developing Parkinson's disease (PD). Recent evidence suggests that exercise may delay or prevent the development of clinically overt symptoms of PD in people at risk of PD. We determined whether LRRK2 G2019S mutation carriers with and without manifest PD are aware of the relationship between exercise and PD and how they differ in awareness, barriers and motivators to exercise. METHODS: We deployed a survey among 4422 LRRK2 G2019S mutation carriers. In total, 505 (11.4%) of them completed the survey, of whom 105 had self-reported manifest PD. RESULTS: Ninety-two percent of the LRRK2 G2019S mutation carriers with manifest PD and 63% of those with non-manifest PD were aware of the relationship between exercise and PD. Lack of motivation was the top barrier for those without manifest PD, while having an injury/disability was the most common barrier for those with manifest PD. Improvement of body functioning was the top motivator for both. CONCLUSION: The fact that many at-risk individuals are not aware of the importance of exercise and would exercise more with fewer barriers creates opportunities for trials using exercise as a possible prevention strategy for PD.

Inter-annual variability patterns of reef cryptobiota in the central Red Sea across a shelf gradient.

The combination of molecular tools, standard surveying techniques, and long-term monitoring programs are relevant to understanding environmental and ecological changes in coral reef communities. Here we studied temporal variability in cryptobenthic coral reef communities across the continental shelf in the central Red Sea spanning 6 years (three sampling periods: 2013-2019) and including the 2015 mass bleaching event. We used a combination of molecular tools (barcoding and metabarcoding) to assess communities on Autonomous Reef Monitoring Structures (ARMS) as a standardized sampling approach. Community composition associated with ARMS for both methodologies (barcoding and metabarcoding) was statistically different across reefs (shelf position) and time periods. The partition of beta diversity showed a higher turnover and lower nestedness between pre-bleaching and post-bleaching samples than between the two post-bleaching periods, revealing a community shift from the bleaching event. However, a slight return to the pre-bleaching community composition was observed in 2019 suggesting a recovery trajectory. Given the predictions of decreasing time between bleaching events, it is concerning that cryptobenthic communities may not fully recover and communities with new characteristics will emerge. We observed a high turnover among reefs for all time periods, implying a homogenization of the cryptobiome did not occur across the cross shelf following the 2015 bleaching event. It is possible that dispersal limitations and the distinct environmental and benthic structures present across the shelf maintained the heterogeneity in communities among reefs. This study has to the best of our knowledge presented for the first time a temporal aspect into the analysis of ARMS cryptobenthic coral reef communities and encompasses a bleaching event. We show that these structures can detect cryptic changes associated with reef degradation and provides support for these being used as long-term monitoring tools.

The affect of personality traits and decision-making style on postoperative quality of life and distress in patients undergoing pelvic exenteration.

AIM: Our aim was to identify whether personality traits and decision-making styles affect quality of life (QoL) outcomes and levels of psychological distress following pelvic exenteration (PE). METHOD: Patients undergoing PE between 2008 and 2015 were identified from a prospectively maintained database at a single quaternary referral centre. Patients were invited to complete two validated questionnaires, with the Big Five inventory being used to assess personality traits and the Melbourne Decision Making Questionnaire to determine decision-making style. Data on QoL outcomes and distress from the prospectively established database were utilized. QoL with respect to both physical and mental health components was measured using Short Form 36 version 2 (SF-36v2) and the Functional Assessment of Cancer Therapy - Colorectal (FACT-C). Distress was measured using the Distress Thermometer. Postoperative pain scores were also measured using SF-36v2. RESULTS: Of the 93 patients eligible for participation, 42 returned the study questionnaire. On multivariate analysis, neuroticism was the most significant predictor of poorer QoL and increased levels of distress, consistent across all of the measures utilized and at the different time points used. Other personality traits showed an isolated statistically significant impact upon QoL. There were no significant findings with respect to decision-making style. Apart from neuroticism, the most significant predictor of QoL was the number of major complications for the patient. CONCLUSION: Patients demonstrating neurotic personality traits show poorer QoL outcomes and higher levels of distress following PE. Identification of these patients would allow targeted pre- and postoperative intervention to improve outcomes following PE.

Optimization of energy transport in the Fenna-Matthews-Olson complex via site-varying pigment-protein interactions.

Energy transport in photosynthetic systems can be tremendously efficient. In particular, we study exciton transport in the Fenna-Mathews-Olson (FMO) complex found in green sulphur bacteria. The exciton dynamics and energy transfer efficiency depend on the interaction of excited chromophores with their environment. Based upon realistic, site-dependent models of the system-bath coupling, we present results that suggest that this interaction may be optimized in the case of FMO. Furthermore we verify two transport pathways and note that one is dominated by coherent dynamics and the other by incoherent energy dissipation. In particular, we note a significant correlation between energy transport efficiency and coherence for exciton transfer from bacteriochlorophyll (BChl) 8 to BChl 4.

Coral reef degradation affects the potential for reef recovery after disturbance.

The loss of coral cover is often accompanied by an increase of benthic algae, a decline in biodiversity and habitat complexity. However, it remains unclear how surrounding communities influence the trajectories of re-colonization between pulse disturbance events. Over a 12-month field experiment in the central Red Sea, we examined how healthy (hard-coral dominated) and degraded (algae-dominated) reef areas influence recruitment and succession patterns of benthic reef foundation communities on bare substrates. Crustose coralline algae and other calcifiers were important colonizers in the healthy reef area, promoting the accumulation of inorganic carbon. Contrary, substrates in the degraded area were predominantly colonized by turf algae, lowering the accumulation of inorganic carbon by 178%. While coral larvae settlement similarly occurred in both habitats, degraded areas showed 50% fewer recruits. Our findings suggest that in degraded reefs the replenishment of adult coral populations is reduced due to recruitment inhibition through limited habitat complexity and grazing pressure, thereby restraining reef recovery.

Pre-emptive triple tributary internal iliac vein ligation reduces catastrophic haemorrhage from sacrectomy during pelvic exenterative surgery.

BACKGROUND: The risk of significant haemorrhage in pelvic exenterative surgery requiring sacrectomy has been well described. Patients requiring a sacrectomy above S3 are placed in the prone position, posing an increased challenge to gaining control of haemorrhage when it occurs. We describe a technique of pre-emptive control of the internal iliac vein and its three named tributaries to tame the pelvis prior to sacrectomy. METHODS: A retrospective, descriptive analysis was performed on a cohort of 25 consecutive patients operated on by one of the authors (AA E) between January 2005 and December 2010; all of whom underwent pre-emptive internal iliac vein triple tributary venous ligation, either unilaterally or bilaterally prior to sacrectomy above the level of S3. RESULTS: The cohort of patients was a heterogenous group ranging in age from 20 to 80 (mean 46.2) years, with primary tumours in 19 (76%), and secondary tumours in 6 (24%). Median operating time was 8.5 h (range 2.32-19.67 h). Median blood loss was 5500 mL (range 1600-18000 mL), with associated median transfusion of packed red blood cells of 9 units (range 0-34 units). Average stay in the intensive care unit was 1 day (range 0-10 days), with a median length of hospital stay of 18 days (range 5-148 days). There was no intraoperative mortality, with one death at 30 days secondary to gram-negative septicaemia. Postoperative morbidity occurred in 17 (68%) patients. CONCLUSION: Our results show that pre-emptive triple tributary internal iliac vein ligation is feasible for taming the pelvis prior to sacrectomy in the prone position where control of significant haemorrhage can prove challenging. The technique has broader relevance for visceral resections in the pelvis involving the pelvic side walls.

Influence of coral cover and structural complexity on the accuracy of visual surveys of coral-reef fish communities.

Using manipulated patch reefs with combinations of varying live-coral cover (low, medium and high) and structural complexity (low and high), common community metrics (abundance, diversity, richness and community composition) collected through standard underwater visual census techniques were compared with exhaustive collections using a fish anaesthetic (clove oil). This study showed that reef condition did not influence underwater visual census estimates at a community level, but reef condition can influence the detectability of some small and cryptic species and this may be exacerbated if surveys are conducted on a larger scale.

Large predatory coral trout species unlikely to meet increasing energetic demands in a warming ocean.

Increased ocean temperature due to climate change is raising metabolic demands and energy requirements of marine ectotherms. If productivity of marine systems and fisheries are to persist, individual species must compensate for this demand through increasing energy acquisition or decreasing energy expenditure. Here we reveal that the most important coral reef fishery species in the Indo-west Pacific, the large predatory coral trout Plectropomus leopardus (Serranidae), can behaviourally adjust food intake to maintain body-condition under elevated temperatures, and acclimate over time to consume larger meals. However, these increased energetic demands are unlikely to be met by adequate production at lower trophic levels, as smaller prey species are often the first to decline in response to climate-induced loss of live coral and structural complexity. Consequently, ubiquitous increases in energy consumption due to climate change will increase top-down competition for a dwindling biomass of prey, potentially distorting entire food webs and associated fisheries.

Creating a Stable Oxide at the Surface of Black Phosphorus.

The stability of the surface of in situ cleaved black phosphorus crystals upon exposure to atmosphere is investigated with synchrotron-based photoelectron spectroscopy. After 2 days atmosphere exposure a stable subnanometer layer of primarily P2O5 forms at the surface. The work function increases by 0.1 eV from 3.9 eV for as-cleaved black phosphorus to 4.0 eV after formation of the 0.4 nm thick oxide, with phosphorus core levels shifting by <0.1 eV. The results indicate minimal charge transfer, suggesting that the oxide layer is suitable for passivation or as an interface layer for further dielectric deposition.

Oxygen defects in phosphorene.

Surface reactions with oxygen are a fundamental cause of the degradation of phosphorene. Using first-principles calculations, we show that for each oxygen atom adsorbed onto phosphorene there is an energy release of about 2 eV. Although the most stable oxygen adsorbed forms are electrically inactive and lead only to minor distortions of the lattice, there are low energy metastable forms which introduce deep donor and/or acceptor levels in the gap. We also propose a mechanism for phosphorene oxidation involving reactive dangling oxygen atoms and we suggest that dangling oxygen atoms increase the hydrophilicity of phosphorene.

Increasing ocean temperatures reduce activity patterns of a large commercially important coral reef fish.

Large-bodied fish are critical for sustaining coral reef fisheries, but little is known about the vulnerability of these fish to global warming. This study examined the effects of elevated temperatures on the movement and activity patterns of the common coral trout Plectropomus leopardus (Serranidae), which is an important fishery species in tropical Australia and throughout the Indo West-Pacific. Adult fish were collected from two locations on Australia's Great Barrier Reef (23°S and 14°S) and maintained at one of four temperatures (24, 27, 30, 33 °C). Following >4 weeks acclimation, the spontaneous swimming speeds and activity patterns of individuals were recorded over a period of 12 days. At 24-27 °C, spontaneous swimming speeds of common coral trout were 0.43-0.45 body lengths per second (bls(-1)), but dropped sharply to 0.29 bls(-1) at 30 °C and 0.25 bls(-1) at 33 °C. Concurrently, individuals spent 9.3-10.6% of their time resting motionless on the bottom at 24-27 °C, but this behaviour increased to 14.0% at 30 °C and 20.0% of the time at 33 °C (mean ± SE). The impact of temperature was greatest for smaller individuals (<45 cm TL), showing significant changes to swimming speeds across every temperature tested, while medium (45-55 cm TL) and large individuals (>55 cm TL) were first affected by 30 °C and 33 °C, respectively. Importantly, there was some indication that populations can adapt to elevated temperature if presented with adequate time, as the high-latitude population decreased significantly in swimming speeds at both 30 °C and 33 °C, while the low-latitude population only showed significant reductions at 33 °C. Given that movement and activity patterns of large mobile species are directly related to prey encounter rates, ability to capture prey and avoid predators, any reductions in activity patterns are likely to reduce overall foraging and energy intake, limit the energy available for growth and reproduction, and affect the fitness and survival of individuals and populations.

Iterative linearized density matrix propagation for modeling coherent excitation energy transfer in photosynthetic light harvesting.

Rather than incoherent hopping between chromophores, experimental evidence suggests that the excitation energy transfer in some biological light harvesting systems initially occurs coherently, and involves coherent superposition states in which excitation spreads over multiple chromophores separated by several nanometers. Treating such delocalized coherent superposition states in the presence of decoherence and dissipation arising from coupling to an environment is a significant challenge for conventional theoretical tools that either use a perturbative approach or make the Markovian approximation. In this paper, we extend the recently developed iterative linearized density matrix (ILDM) propagation scheme [E. R. Dunkel et al., J. Chem. Phys. 129, 114106 (2008)] to study coherent excitation energy transfer in a model of the Fenna-Matthews-Olsen light harvesting complex from green sulfur bacteria. This approach is nonperturbative and uses a discrete path integral description employing a short time approximation to the density matrix propagator that accounts for interference between forward and backward paths of the quantum excitonic system while linearizing the phase in the difference between the forward and backward paths of the environmental degrees of freedom resulting in a classical-like treatment of these variables. The approach avoids making the Markovian approximation and we demonstrate that it successfully describes the coherent beating of the site populations on different chromophores and gives good agreement with other methods that have been developed recently for going beyond the usual approximations, thus providing a new reliable theoretical tool to study coherent exciton transfer in light harvesting systems. We conclude with a discussion of decoherence in independent bilinearly coupled harmonic chromophore baths. The ILDM propagation approach in principle can be applied to more general descriptions of the environment.

An in vitro mechanical comparison of tibial plateau levelling osteotomy plates.

An in vitro mechanical study was performed to compare the fatigue properties and the loads to failure of four plate designs that are used to stabilise the tibial plateau levelling osteotomy (TPLO). Seventy-two gapped osteotomy models were created using 3.5 mm versions of the following plates: a standard TPLO plate, a low profile TPLO plate, a locking TPLO plate (LocP), and a broad locking TPLO plate (bLocP). The 18 constructs for each plate design were sub-divided into three identical groups of six. Six constructs were mounted in a materials testing device and subjected to cyclic compressive loading until failure was observed or one-million cycles were achieved. Additionally, six constructs of each plate design were tested in compressive axial loading and six others in four-point bending in a load-to-failure manner. To provide residual strength comparisons, the six constructs undergoing cyclic fatigue compression testing were also tested in axial compressive loading. There were not any significant differences in stiffness between plates tested in axial compressive loading. However, mean loads at failure were higher for the LocP and bLocP constructs. The bLocP had a significantly higher mean stiffness and mean load at failure compared to the other constructs tested in four-point bending.

Ultrafast H2 and D2 rotational Raman responses in near critical CO2: an experimental and theoretical study of anisotropic solvation dynamics.

The optical heterodyne detected anisotropic rotational Raman responses of H(2) and D(2) (22 mol %) in a near critical CO(2) (rho(*) = rho/rho(c) = 0.8, T = 308 K) solution are reported. J-specific rotational Raman correlation functions (RCFs) for the S(J) transitions of H(2) (J = 0,1,2) and D(2) (J = 0,1,2,3) in this CO(2) solution are determined from these measurements. A mixed classical-quantum simulation methodology results in RCFs that are in excellent agreement with the experimentally derived J-specific responses. The observed S(J) coherence decay time scales, J-dependence, rotor mass dependence, and solvent-induced transition frequency shifts are well captured by these simulations. Pure dephasing of these rotational Raman transitions is shown to be close to the homogeneous limit of the standard Kubo line shape analysis and attributable to the rotor center-of-mass translation in an anisotropic solvent cage. Rotor translational motion in the vicinity of a single CO(2) appears to dominate this dephasing mechanism. Mixed classical-quantum simulations, incorporating the effects of solution fluctuation driven nonadiabatic coupling of instantaneous adiabatic states, including full J-mixing, are required for the agreement between theory and experiment obtained here. Simulations of the classically excited angular kinetic energy of D(2) rotors are used as an estimate of T(1) relaxation rates and are found to be negligible compared to the D(2) rotational Raman coherence time scale. These results are discussed in the context of previous mixed classical-quantum and rotational friction calculations of the dephasing and energy relaxation contributions to H(2) rotational Raman coherence decays. Advantages of time domain acquisition of these rotational Raman responses as compared to spontaneous Raman measurements are illustrated here.

Iterative linearized approach to nonadiabatic dynamics.

This paper presents a new approach to propagating the density matrix based on a time stepping procedure arising from a Trotter factorization and combining the forward and backward incremental propagators. The sums over intermediate states of the discrete quantum subsystem are implemented by a Monte Carlo surface hopping-like procedure, while the integrals over the continuous variables are performed using a linearization in the difference between the forward and backward paths of these variables leading to classical-like equations of motion with forces determined by the quantum subsystem states. The approach is tested on several models and numerical convergence is explored.

Quantum initial condition sampling for linearized density matrix dynamics: Vibrational pure dephasing of iodine in krypton matrices.

This paper reviews the linearized path integral approach for computing time dependent properties of systems that can be approximated using a mixed quantum-classical description. This approach is applied to studying vibrational pure dephasing of ground state molecular iodine in a rare gas matrix. The Feynman-Kleinert optimized harmonic approximation for the full system density operator is used to sample initial conditions for the bath degrees of freedom. This extremely efficient approach is compared to alternative initial condition sampling techniques at low temperatures where classical initial condition sampling yields dephasing rates that are nearly an order of magnitude too slow compared to quantum initial condition sampling and experimental results.

LAND-map, a linearized approach to nonadiabatic dynamics using the mapping formalism.

We present a new approach for calculating quantum time correlation functions for systems whose dynamics exhibits relevant nonadiabatic effects. The method involves partial linearization of the full quantum path-integral expression for the time correlation function written in the nonadiabatic mapping Hamiltonian formalism. Our analysis gives an algorithm which is both numerically efficient and accurate as we demonstrate in test calculations on the spin-boson model where we find results in good agreement with exact calculations. The accuracy of our new approach is comparable to that of calculations performed using other approximate methods over a relatively broad range of model parameters. However, our method converges relatively quickly when compared with most alternative schemes. These findings are very encouraging in view of the application of the new method for studying realistic nonadiabatic model problems in the condensed phase.

Ultrafast nonadiabatic dynamics: quasiclassical calculation of the transient photoelectron spectrum of I2(-).(CO2)8.

In this paper we investigate the transient photoelectron spectrum of I2(-) in CO2 clusters recently measured by Neumark and co-workers. This work reveals a rich excited state dynamics with various competing electronic output channels. We find good agreement with experiments and we are able to relate the transient signal to different dynamical events that occur during the evolution of the cluster and its fragmentation products.