2,318 research outputs found
OPTIMAL IRRIGATION PIVOT LOCATION ON IRREGULARLY SHAPED FIELDS
Although annual rainfall in the Southeast is adequate, its distribution is a potential constraint to agricultural production. Farmers require production information concerning efficient use of irrigation technology adapted to regional growing conditions. Selection of optimal position, size, and number of pivots in center pivot irrigation systems poses special problems on small, irregularly shaped fields. In the southeastern United States, field size and shape are often varied and irregular. A mixed integer programming model was constructed to assist in irrigation investment decisions. The model is illustrated using irrigated peanut production in southeast Alabama. Results indicate the importance of economic engineering considerations.Farm Management,
Artificial Intelligence
Contains reports on four research projects.M.I.T. Research Laboratory of ElectronicsM.I.T. Computation Cente
Direct and indirect effects of attention and visual function on gait impairment in Parkinson’s disease: influence of task and turning
Gait impairment is a core feature of Parkinson’s disease (PD) which has been linked to cognitive and visual deficits, but interactions between these features are poorly understood. Monitoring saccades allows investigation of real-time cognitive and visual processes and their impact on gait when walking. This study explored; 1) saccade frequency when walking under different attentional manipulations of turning and dual-task; and 2) direct and indirect relationships between saccades, gait impairment, vision and attention. Saccade frequency (number of fast eye-movements per-second) was measured during gait in 60 PD and 40 age-matched control participants using a mobile eye-tracker. Saccade frequency was significantly reduced in PD compared to controls during all conditions. However, saccade frequency increased with a turn and decreased under dual-task for both groups. Poorer attention directly related to saccade frequency, visual function and gait impairment in PD, but not controls. Saccade frequency did not directly relate to gait in PD, but did in controls. Instead, saccade frequency and visual function deficit indirectly impacted gait impairment in PD, which was underpinned by their relationship with attention. In conclusion, our results suggest a vital role for attention with direct and indirect influences on gait impairment in PD. Attention directly impacted saccade frequency, visual function and gait impairment in PD, with connotations for falls. It also underpinned indirect impact of visual and saccadic impairment on gait. Attention therefore represents a key therapeutic target that should be considered in future research
Production and detection of atomic hexadecapole at Earth's magnetic field
Anisotropy of atomic states is characterized by population differences and
coherences between Zeeman sublevels. It can be efficiently created and probed
via resonant interactions with light, the technique which is at the heart of
modern atomic clocks and magnetometers. Recently, nonlinear magneto-optical
techniques have been developed for selective production and detection of higher
polarization moments, hexadecapole and hexacontatetrapole, in the ground states
of the alkali atoms. Extension of these techniques into the range of
geomagnetic fields is important for practical applications. This is because
hexadecapole polarization corresponding to the Zeeman coherence,
with maximum possible for electronic angular momentum and
nuclear spin , is insensitive to the nonlinear Zeeman effect (NLZ). This
is of particular interest because NLZ normally leads to resonance splitting and
systematic errors in atomic magnetometers. However, optical signals due to the
hexadecapole moment decline sharply as a function of magnetic field. We report
a novel method that allows selective creation of a macroscopic long-lived
ground-state hexadecapole polarization. The immunity of the hexadecapole signal
to NLZ is demonstrated with F=2 Rb atoms at Earth's field.Comment: 4 pages, 5 figure
Balance and coordination after viewing stereoscopic 3D television.
Manufacturers and the media have raised the possibility that viewing stereoscopic 3D television (S3D TV) may cause temporary disruption to balance and visuomotor coordination. We looked for evidence of such effects in a laboratory-based study. Four hundred and thirty-three people aged 4-82 years old carried out tests of balance and coordination before and after viewing an 80 min movie in either conventional 2D or stereoscopic 3D, while wearing two triaxial accelerometers. Accelerometry produced little evidence of any change in body motion associated with S3D TV. We found no evidence that viewing the movie in S3D causes a detectable impairment in balance or in visuomotor coordination
Measurement of Dielectric Suppression of Bremsstrahlung
In 1953, Ter-Mikaelian predicted that the bremsstrahlung of low energy
photons in a medium is suppressed because of interactions between the produced
photon and the electrons in the medium. This suppression occurs because the
emission takes place over on a long distance scale, allowing for destructive
interference between different instantaneous photon emission amplitudes. We
present here measurements of bremsstrahlung cross sections of 200 keV to 20 MeV
photons produced by 8 and 25 GeV electrons in carbon and gold targets. Our data
shows that dielectric suppression occurs at the predicted level, reducing the
cross section up to 75 percent in our data.Comment: 11 pages, format is postscript file, gzip-ed, uuencode-e
'Staying safe' – A narrative review of falls prevention in people with Parkinson’s -'PDSAFE'
This is the author accepted manuscript. The final version is available from Taylor & Francis via the DOI in this record.Background:
Parkinson's disease demonstrates a spectrum of motor and non-motor symptoms. Falling is
common and disabling. Current medical management shows minimal impact to reduce falls, or
fall related risk factors such as deficits in gait, strength and postural instability. Despite evidence
supporting rehabilitation in reducing fall risk factors, the most appropriate intervention to reduce
overall fall rate remains inconclusive.
This paper aims to 1) synthesise current evidence and conceptual models of falls rehabilitation in
Parkinson's in a narrative review; and based on this evidence 2) introduce the treatment protocol
used in the falls prevention, multi-centre clinical trial 'PDSAFE'.
Method: Search of four bibliographic databases using the terms ‘Parkinson*’ and ‘Fall*’ combined
with each of the following; ‘Rehab*, Balanc*, Strength*, Strateg*and Exercis*' and a framework for
narrative review was followed.
3557 papers were identified, 416 were selected for review. The majority report the impact of
rehabilitation on isolated fall risk factors. Twelve directly measure the impact on overall fall rate.
Discussion: Results were used to construct a narrative review with conceptual discussion based
on the 'International Classification of Functioning’, leading to presentation of the 'PDSAFE'
intervention protocol.
Conclusion: Evidence suggests training single, fall risk factors may not affect overall fall rate.
Combining with behavioural and strategy training in a functional, personalised multi-dimensional
model, addressing all components of the ‘International Classification of Functioning’ is likely to
provide a greater influence on falls reduction.
'PDSAFE' is a multi-dimensional, physiotherapist delivered, individually tailored, progressive,
home-based programme. It is designed with a strong evidence based approach and illustrates a
model for the clinical delivery of the conceptual theory discussed.This project was funded by the National Institute for Health Research Health Technologies Assessment
programme (project number 10/57/21). VG is supported by the National Institute of Health Research
Collaboration for Applied Health Research and Care South West Peninsula.
Germline Maintenance Through the Multifaceted Activities of GLH/Vasa in
Vasa homologs are ATP-dependent DEAD-box helicases, multipotency factors, and critical components that specify and protect the germline. They regulate translation, amplify piwi-interacting RNAs (piRNAs), and act as RNA solvents; however, the limited availability of mutagenesis-derived alleles and their wide range of phenotypes have complicated their analysis. Now, with clustered regularly interspaced short palindromic repeats (CRISPR/Cas9), these limitations can be mitigated to determine why protein domains have been lost or retained throughout evolution. Here, we define the functional motifs of GLH-1/Vasa i
Upper body accelerations as a biomarker of gait impairment in the early stages of Parkinson’s disease
Background
Changes in upper body (UB) motion during gait may be a marker of incipient pathology, intervention response and disease progression in Parkinson’s disease (PD), which if independent from the lower body motion, might provide an improved assessment of gait.
Research question
This study aimed to test this hypothesis and establish whether variables calculated from accelerations measured on the UB are unique from spatiotemporal characteristics and can contribute to an improved classification of PD gait.
Methods
Data was obtained from 70 people with PD (69.2 ± 9.9 y.o., UPDRS III: 36.9 ± 12.3) and 64 age-matched controls (71.6 ± 6.8 y.o.). Spatiotemporal characteristics were measured using a pressure sensitive mat (GAITRite). Head and pelvis accelerations were synchronously measured with wearable inertial sensors (Opal, APDM). Pearson’s product-moment correlations were calculated between 49 selected variables from UB accelerations (representing magnitude, smoothness, regularity, symmetry and attenuation) and 16 traditional spatiotemporal characteristics (representing pace, variability, rhythm, asymmetry and postural control). Univariate and multivariate regression analysis was used to test the variables ability to classify PD gait.
Results
The variables were mostly unique from each other (67% of variables recorded an r < 0.3). Univariate and multivariate analysis showed that UB variables were moderately better at classifying PD gait than the spatiotemporal characteristics (Univariate: 0.70 to 0.81, Multivariate: 0.88 to 0.91 AUC).
Significance
This study showed for the first time that, if aiming at objective and optimal sensitive biomarkers for PD, UB variables should be measured in conjunction with spatiotemporal characteristics to obtain a more holistic assessment of PD gait for use in a clinical or free-living environment
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