1,233 research outputs found
Control of open-loop unstable processes with time delay using PI/PID controllers specified using tuning rules: An outline survey
The ability of PI and PID controllers to compensate many practical processes has led to their wide acceptance in industrial applications. The requirement to choose two or three controller parameters is conveniently done using tuning rules. Starting with a general discussion of industrial practice, the paper provides a survey of tuning rules for continuous time PI and PID control of open-loop unstable time-delayed single-input, single-output (SISO) processes
Midpalatal implants vs headgear for orthodontic anchorage - a randomized clinical trial: Cephalometric results
OBJECTIVE: To compare the clinical effectiveness of the mid-palatal implant as a method of reinforcing anchorage during orthodontic treatment with that of conventional extra-oral anchorage.
DESIGN: A prospective, randomized, clinical trial
Setting: Chesterfield and North Derbyshire Royal Hospital NHS Trust and the Charles Clifford Dental Hospital, Sheffield.
SUBJECTS AND METHODS: 51 orthodontic patients between the ages of 12 and 39, with a class II division 1 malocclusion and ‘absolute anchorage’ requirements were randomly allocated to either receive a mid-palatal implant or headgear to reinforce orthodontic anchorage. The main outcome of the trial was to compare the mesial movement of the molars and incisors of the two treatment groups between T1 (start) and T2 (end of anchorage reinforcement) as measured from cephalometric radiographs.
RESULTS: The reproducibility of the measuring technique was acceptable. There were significant differences between the T1 and T2 measurements within the implant group for the position of the maxillary central incisor (p<0.001), position of the maxillary molar (p=0.009) and position of the mandibular molar (p<0.001). There were significant differences within the headgear group for the position of the mandibular central incisor (p<0.045), position of the maxillary molar (p=<0.001) and position of the mandibular molar (p<0.001). All the skeletal and dental points moved mesially more in the headgear group during treatment than in the implant group. These ranged from an average of 0.5mm more mesial for the mandibular permanent molar to 1.5mm more mesial for the maxillary molar and mandibular base. None of the treatment changes between the implant and headgear groups were statistically significant.
CONCLUSIONS: Mid-palatal implants are an acceptable technique for reinforcing anchorage in the orthodontic patient
Non-Perturbative Tachyon Potential from the Wilsonian Renormalization Group
The derivative expansion of the Wilsonian renormalization group generates
additional terms in the effective beta-functions not present in the
perturbative approach. Applied to the nonlinear sigma model, to lowest order
the vanishing of the beta-function for the tachyon field generates an equation
analogous to that found in open string field theory. Although the nonlinear
term depends on the cut-off function, this arbitrariness can be removed by a
rescaling of the tachyon field.Comment: 6 pages, further references adde
Midpalatal implants vs headgear for orthodontic anchorage - a randomized clinical trial: Cephalometric results
OBJECTIVE: To compare the clinical effectiveness of the mid-palatal implant as a method of reinforcing anchorage during orthodontic treatment with that of conventional extra-oral anchorage.
DESIGN: A prospective, randomized, clinical trial
Setting: Chesterfield and North Derbyshire Royal Hospital NHS Trust and the Charles Clifford Dental Hospital, Sheffield.
SUBJECTS AND METHODS: 51 orthodontic patients between the ages of 12 and 39, with a class II division 1 malocclusion and ‘absolute anchorage’ requirements were randomly allocated to either receive a mid-palatal implant or headgear to reinforce orthodontic anchorage. The main outcome of the trial was to compare the mesial movement of the molars and incisors of the two treatment groups between T1 (start) and T2 (end of anchorage reinforcement) as measured from cephalometric radiographs.
RESULTS: The reproducibility of the measuring technique was acceptable. There were significant differences between the T1 and T2 measurements within the implant group for the position of the maxillary central incisor (p<0.001), position of the maxillary molar (p=0.009) and position of the mandibular molar (p<0.001). There were significant differences within the headgear group for the position of the mandibular central incisor (p<0.045), position of the maxillary molar (p=<0.001) and position of the mandibular molar (p<0.001). All the skeletal and dental points moved mesially more in the headgear group during treatment than in the implant group. These ranged from an average of 0.5mm more mesial for the mandibular permanent molar to 1.5mm more mesial for the maxillary molar and mandibular base. None of the treatment changes between the implant and headgear groups were statistically significant.
CONCLUSIONS: Mid-palatal implants are an acceptable technique for reinforcing anchorage in the orthodontic patient
Observation of HCN hyperfine line anomalies towards low- and high-mass star-forming cores
HCN is becoming a popular choice of molecule for studying star formation in
both low- and high-mass regions and for other astrophysical sources from comets
to high-redshift galaxies. However, a major and often overlooked difficulty
with HCN is that it can exhibit non-local thermodynamic equilibrium (non-LTE)
behaviour in its hyperfine line structure. Individual hyperfine lines can be
strongly boosted or suppressed. In low-mass star-forming cloud observations,
this could possibly lead to large errors in the calculation of opacity and
excitation temperature, while in massive star-forming clouds, where the
hyperfine lines are blended due to turbulent broadening, errors will arise in
infall measurements that are based on the separation of the peaks in a
self-absorbed profile. The underlying line shape cannot be known for certain if
hyperfine anomalies are present. We present a first observational investigation
of these anomalies across a range of conditions and transitions by carrying out
a survey of low-mass starless cores (in Taurus & Ophiuchus) and high-mass
protostellar objects (in the G333 giant molecular cloud) using hydrogen cyanide
(HCN) J=1-0 and J=3-2 emission lines. We quantify the degree of anomaly in
these two rotational levels by considering ratios of individual hyperfine lines
compared to LTE values. We find that all the cores observed show some degree of
anomaly while many of the lines are severely anomalous. We conclude that HCN
hyperfine anomalies are common in both lines in both low-mass and high-mass
protostellar objects, and we discuss the differing hypotheses for the
generation of the anomalies. In light of the results, we favour a line overlap
effect for the origins of the anomalies. We discuss the implications for the
use of HCN as a dynamical tracer and suggest in particular that the J=1-0,
F=0-1 hyperfine line should be avoided in quantitative calculations.Comment: 17 pages, 8 figure
Area estimations of cultivated organic soils in Ireland: reducing GHG reporting uncertainties
peer-reviewed Cultivated organic soils, which are a large source of CO2 emissions, are of particular interest in the Republic of Ireland where peatlands cover 20 % of the landscape. For accurate accounting and national reporting of greenhouse gas (GHG) emissions, there is a need to calculate the total land area used for cultivation activity on drained organic soils. Peatlands (organic soils) in Ireland are also used for arable farming, which results in particularly high greenhouse gas emissions per unit area. However, the Irish National Inventory Report to the United Nations Framework Convention on Climate Change lacks mention of this type of land use. The actual area of organic soils under arable land use (cropland) in Ireland has, thus far, not been quantified. Here we provide a first estimate of the area of organic soil that is used for arable farming in Ireland. Through map overlay analysis using GIS in combination with probability sampling and ground truthing, we estimate the area of organic soils under arable cropping at 1,235 ha, which is considerably lower than the estimate of 3,688 ha based on map overlays alone. This research provides information to support improved accounting of organic soils under cultivation and may contribute to reducing uncertainty in national reporting of GHG emissions, thus providing a more reliable basis for strategies aimed at reducing GHG emissions in Ireland in the future.PUBLISHEDpeer-reviewe
User Studies for Digital Library Development
As the information environment becomes increasingly electronic, digital libraries have proliferated, but the focus has often been on innovations in technology and not the user. Research and analysis of users is essential to fine-tune the content and approach of digital libraries to the diverging requirements and expectations of incredibly varied communities and to ensure libraries are effective, accessible and sustainable in the long term. This book provides a clear overview of the user studies domain and user issues in digital libraries
Bayesian analysis of the low-resolution polarized 3-year WMAP sky maps
We apply a previously developed Gibbs sampling framework to the foreground
corrected 3-yr WMAP polarization data and compute the power spectrum and
residual foreground template amplitude posterior distributions. We first
analyze the co-added Q- and V-band data, and compare our results to the
likelihood code published by the WMAP team. We find good agreement, and thus
verify the numerics and data processing steps of both approaches. However, we
also analyze the Q- and V-bands separately, allowing for non-zero EB
cross-correlations and including two individual foreground template amplitudes
tracing synchrotron and dust emission. In these analyses, we find tentative
evidence of systematics: The foreground tracers correlate with each of the Q-
and V-band sky maps individually, although not with the co-added QV map; there
is a noticeable negative EB cross-correlation at l <~ 16 in the V-band map; and
finally, when relaxing the constraints on EB and BB, noticeable differences are
observed between the marginalized band powers in the Q- and V-bands. Further
studies of these features are imperative, given the importance of the low-l EE
spectrum on the optical depth of reionization tau and the spectral index of
scalar perturbations n_s.Comment: 5 pages, 4 figures, submitted to ApJ
Chitosan gel film bandages: correlating structure, composition, and antimicrobial properties
Chitosan gel films were successfully obtained by evaporation cast from chitosan solutions in aqueous acidic solutions of organic acids (lactic and acetic acid) as gel film bandages, with a range of additives that directly influence film morphology and porosity. We show that the structure and composition of a wide range of 128 thin gel films, is correlated to the antimicrobial properties, their biocompatibility and resistance to biodegradation. Infrared spectroscopy and solid-state 13C nuclear magnetic resonance spectroscopy was used to correlate film molecular structure and composition to good antimicrobial properties against 10 of the most prevalent Gram positive and Gram negative bacteria. Chitosan gel films reduce the number of colonies after 24 h of incubation by factors of ∼105–107 CFU/mL, compared with controls. For each of these films, the structure and preparation condition has a direct relationship to antimicrobial activity and effectiveness. These gel film bandages also show excellent stability against biodegradation with lysozyme under physiological conditions (5% weight loss over a period of 1 month, 2% in the first week), allowing use during the entire healing process. These chitosan thin films and subsequent derivatives hold potential as low-cost, dissolvable bandages, or second skin, with antimicrobial properties that prohibit the most relevant intrahospital bacteria that infest burn injuries
Palladium-catalyzed coupling reactions for the functionalization of Si surfaces: superior stability of alkenyl monolayers
Palladium-catalyzed Suzuki, Heck, and Sonogashira coupling reactions were studied as reaction protocols for organic modification of Si surfaces. These synthetically useful protocols allow for surface modification of alkene, alkyne, and halide terminated surfaces. Surface oxidation and metal contamination were assessed by X-ray photoelectron spectroscopy. The nature of the primary passivation layer was an important factor in the oxidation resistance of the Si surface during the secondary functionalization. Specifically, the use of alkynes as the primary functionalization layer gave superior stability compared to alkene analogues. The ability to utilize Pd-catalyzed coupling chemistries on Si surfaces opens great versatility for potential molecular and nanoscale electronics and sensing/biosensing applications
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