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Narrow-windrow burning has been a successful form of harvest weed seed control in Australian cropping systems, but little is known about the efficacy of narrow-windrow burning on weed seeds infesting U.S. cropping systems. An experiment was conducted using a high-fire kiln that exposed various grass and broadleaf weed seeds to temperatures of 200, 300, 400, 500, and 600 C for 20, 40, 60, and 80 s to determine the temperature and time needed to kill weed seeds. Weeds evaluated included Italian ryegrass, barnyardgrass, johnsongrass, sicklepod, Palmer amaranth, prickly sida, velvetleaf, pitted morningglory, and hemp sesbania. Two field experiments were also conducted over consecutive growing seasons, with the first experiment aimed at determining the amount of heat produced during burning of narrow windrows of soybean harvest residues (chaff and straw) and the effect of this heat on weed seed mortality. The second field experiment aimed to determine the effect of wind speed on the duration and intensity of burning narrow windrows of soybean harvest residues. Following exposure to the highest temperature and longest duration in the kiln, only sicklepod showed any survival (<1% average); however, in most cases, the seeds were completely destroyed (ash). A heat index of only 22,600 was needed to kill all seeds of Palmer amaranth, barnyardgrass, and Italian ryegrass. In the field, all seeds of the evaluated weed species were completely destroyed by narrow-windrow burning of 1.08 to 1.95 kg m−2 of soybean residues. The burn duration of the soybean harvest residues declined as wind speed increased. Findings from the kiln and field experiments show that complete kill is likely for weed seeds concentrated into narrow windrows of burned soybean residues. Given the low cost of implementation of narrow-windrow burning and the seed kill efficacy on various weed species, this strategy may be an attractive option for destroying weed seed.
Mild behavioral impairment (MBI) describes later life acquired, sustained neuropsychiatric symptoms (NPS) in cognitively normal individuals or those with mild cognitive impairment (MCI), as an at-risk state for incident cognitive decline and dementia. We developed an operational definition of MBI and tested whether the presence of MBI was related to caregiver burden in patients with subjective cognitive decline (SCD) or MCI assessed at a memory clinic.
MBI was assessed in 282 consecutive memory clinic patients with SCD (n = 119) or MCI (n = 163) in accordance with the International Society to Advance Alzheimer's Research and Treatment – Alzheimer's Association (ISTAART–AA) research diagnostic criteria. We operationalized a definition of MBI using the Neuropsychiatric Inventory Questionnaire (NPI-Q). Caregiver burden was assessed using the Zarit caregiver burden scale. Generalized linear regression was used to model the effect of MBI domains on caregiver burden.
While MBI was more prevalent in MCI (85.3%) than in SCD (76.5%), this difference was not statistically significant (p = 0.06). Prevalence estimates across MBI domains were affective dysregulation (77.8%); impulse control (64.4%); decreased motivation (51.7%); social inappropriateness (27.8%); and abnormal perception or thought content (8.7%). Affective dysregulation (p = 0.03) and decreased motivation (p=0.01) were more prevalent in MCI than SCD patients. Caregiver burden was 3.35 times higher when MBI was present after controlling for age, education, sex, and MCI (p < 0.0001).
MBI was common in memory clinic patients without dementia and was associated with greater caregiver burden. These data show that MBI is a common and clinically relevant syndrome.
Imaging biomarkers for Alzheimer's disease include medial temporal lobe
atrophy (MTLA) depicted on computed tomography (CT) or magnetic resonance
imaging (MRI) and patterns of reduced metabolism on fluorodeoxyglucose
positron emission tomography (FDG-PET).
To investigate whether MTLA on head CT predicts the diagnostic usefulness
of an additional FDG-PET scan.
Participants had a clinical diagnosis of Alzheimer's disease
(n = 37) or dementia with Lewy bodies (DLB;
n = 30) or were similarly aged controls
(n = 30). We visually rated MTLA on coronally
reconstructed CT scans and, separately and blind to CT ratings, abnormal
appearances on FDG-PET scans.
Using a pre-defined cut-off of MTLA ⩾5 on the Scheltens (0–8) scale, 0/30
controls, 6/30 DLB and 23/30 Alzheimer's disease had marked MTLA. FDG-PET
performed well for diagnosing Alzheimer's disease v. DLB
in the low-MTLA group (sensitivity/specificity of 71%/79%), but in the
high-MTLA group diagnostic performance of FDG-PET was not better than
In the presence of a high degree of MTLA, the most likely diagnosis is
Alzheimer's disease, and an FDG-PET scan will probably not provide
significant diagnostic information. However, in cases without MTLA, if
the diagnosis is unclear, an FDG-PET scan may provide additional
clinically useful diagnostic information.
Background: Previous studies suggest that posterior cortical atrophy may be a useful marker for early onset Alzheimer's disease (AD). Dementia with Lewy bodies (DLB) is associated with less temporal lobe atrophy than AD, though posterior cortical atrophy may be greater. Therefore, we assessed whether visual rating scales for assessing posterior atrophy (PA), medial temporal lobe atrophy (MTA), and ventricular enlargement (VEn) aid in the discrimination between AD, DLB, and normal aging.
Methods: T1-weighted MRI scans acquired at 3 Tesla were visually rated for PA (range 0–3), MTA (range 0–4), and VEn (range 0–3) in older subjects with AD (n = 36), DLB (n = 35), and healthy controls (n = 35). The diagnostic utility of MTA, PA, and VEn visual ratings in distinguishing AD and DLB from controls as well as AD from DLB was investigated.
Results: Significantly higher MTA ratings were associated with AD and DLB compared to controls (p < 0.001). MTA ratings were greater in AD relative to DLB (U = 384.5, p = 0.004). For PA ratings, scores did not differ between groups (p = 0.20). VEn ratings were significantly higher in AD and DLB compared to controls (p = 0.003), but similar between AD and DLB (U = 384.5, p = 0.4).
Conclusions: Unlike findings reported in younger subjects, visual ratings for PA are not a reliable marker at older ages for distinguishing AD from controls, or for distinguishing DLB from AD. However, visual ratings of MTA and VEn may be useful markers in distinguishing both AD and DLB from older subjects without dementia.
The science of extra-solar planets is one of the most rapidly changing areas of astrophysics and since 1995 the number of planets known has increased by almost two orders of magnitude. A combination of ground-based surveys and dedicated space missions has resulted in 560-plus planets being detected, and over 1200 that await confirmation. NASA's Kepler mission has opened up the possibility of discovering Earth-like planets in the habitable zone around some of the 100,000 stars it is surveying during its 3 to 4-year lifetime. The new ESA's Gaia mission is expected to discover thousands of new planets around stars within 200 parsecs of the Sun. The key challenge now is moving on from discovery, important though that remains, to characterisation: what are these planets actually like, and why are they as they are?
In the past ten years, we have learned how to obtain the first spectra of exoplanets using transit transmission and emission spectroscopy. With the high stability of Spitzer, Hubble, and large ground-based telescopes the spectra of bright close-in massive planets can be obtained and species like water vapour, methane, carbon monoxide and dioxide have been detected. With transit science came the first tangible remote sensing of these planetary bodies and so one can start to extrapolate from what has been learnt from Solar System probes to what one might plan to learn about their faraway siblings. As we learn more about the atmospheres, surfaces and near-surfaces of these remote bodies, we will begin to build up a clearer picture of their construction, history and suitability for life.
The Exoplanet Characterisation Observatory, EChO, will be the first dedicated mission to investigate the physics and chemistry of Exoplanetary Atmospheres. By characterising spectroscopically more bodies in different environments we will take detailed planetology out of the Solar System and into the Galaxy as a whole.
EChO has now been selected by the European Space Agency to be assessed as one of four M3 mission candidates.
Cerebrovascular changes and glucocorticoid mediated hippocampal atrophy
are considered relevant for depression-related cognitive deficits,
forming putative treatment targets.
This study examined the relative contribution of cortisol levels, brain
atrophy and white matter hyperintensities to the persistence of cognitive
deficits in older adults with depression.
Thirty-five people aged ⩾60 years with DSM–IV major depression and
twenty-nine healthy comparison controls underwent magnetic resonance
imaging (MRI) and were underwent magnetic resonance imaging (MRI) and
were followed up for 18 months. We analysed the relationship between
baseline salivary cortisol levels, whole brain, frontal lobe and
hippocampal volumes, severity of white matter hyperintensities and
follow-up cognitive function in both groups by testing the interaction
between the groups and these biological measures on tests of memory,
executive functions and processing speed in linear regression models.
Group differences in memory and executive function follow-up scores were
associated with ratings of white matter hyperintensities, especially of
the deep white matter and periventricular regions. Compared with healthy
controls, participants with depression scoring within the third tertile
of white matter hyperintensities dropped two and three standard
deviations in executive function and memory scores respectively. No
biological measure related to group differences in processing speed, and
there were no significant interactions between group and cortisol levels,
or volumetric MRI measures.
White matter hyperintensities, rather than cortisol levels or brain
atrophy, are associated with continuing cognitive impairments in older
adults with depression. The findings suggest that cerebrovascular disease
rather than glucocorticoid-mediated brain damage are responsible for the
persistence of cognitive deficits associated with depression in older
The black and white ruffed lemur, Varecia variegata, which is endemic to Madagascar, is under the threat of extinction due to the loss and fragmentation of its natural habitat, a consequence of deforestation. Behavioural researchers studying a population of V. variegata inhabiting the Manombo Special Reserve, noted that over a 4-year period, none of the family groups within the reserve produced offspring while those in neighbouring populations had been reproductively successful. Inbreeding depression was postulated as the trigger for this occurrence. However, another explanation exists. A cyclone, striking the region in 1997, destroyed a large percentage of the mature fruit-producing trees that V. variegata relied upon as a food source, which is likely to have produced a nutritional deficit. A panel of 25 simple sequence repeat (SSR) markers was utilised to assess the genetic diversity within four V. variegata populations, including individuals from Manombo and three other populations in southeastern Madagascar. The data revealed that the level of genetic diversity apparent within the Manombo population is comparable to the other groups studied. Therefore, it seems probable that genetic factors are not responsible for the recent lack of reproductive success on the part of the V. variegata at Manombo Special Reserve.
Evidence for structural hippocampal change in depression is limited despite reports of neuronal damage due to hypercortisolaemia and vascular pathology.
To compare hippocampal and white matter structural change in demographically matched controls and participants with early-onset and late-onset depression.
High-resolution volumetric magnetic resonance imaging (MRI) and rating of MRI hyperintensities.
A total of 51 people with depression and 39 control participants were included. Participants with late-onset depression had bilateral hippocampal atrophy compared with those with early-onset depression and controls. Hippocampal volumes did not differ between control participants and those with early-onset depression. Age of depression onset correlated (negatively) with hippocampal volume but lifetime duration of depression did not. Hyperintensity ratings did not differ between groups.
Results suggest that acquired biological factors are of greater importance in late-than in early-onset illness and that pathological processes other than exposure to hypercortisolaemia of depression underlie hippocampal atrophy in depression of late life.
We have investigated the effect of ion bombardment on the structure and hardness of thin coatings of TiN/NbN multilayered structures and monolithic films of both TiN and NbN. A radio frequency coil was used to generate an additional inductively coupled plasma between the substrate and the target enabling the sample to be bombarded by a high flux of relatively low energy ions under the appropriate conditions. It is shown that the effect of such bombardment in the case of the monolithic films is to reduce the porosity. This gave an increase in the hardness of both the TiN and the NbN films up to a power of 100 W (using a coil with a cross-sectional area of 2 × 103 mm2). Further increasing the power density led to a decrease in hardness. TiN/NbN multilayer coatings were made under the optimum deposition conditions for the monolithic materials and gave hardnesses greater than those observed in either TiN or NbN and approximately 50% greater than that predicted by a mixtures rule.
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