6,528 research outputs found
Nonparametric Regression, Confidence Regions and Regularization
In this paper we offer a unified approach to the problem of nonparametric
regression on the unit interval. It is based on a universal, honest and
non-asymptotic confidence region which is defined by a set of linear
inequalities involving the values of the functions at the design points.
Interest will typically centre on certain simplest functions in that region
where simplicity can be defined in terms of shape (number of local extremes,
intervals of convexity/concavity) or smoothness (bounds on derivatives) or a
combination of both. Once some form of regularization has been decided upon the
confidence region can be used to provide honest non-asymptotic confidence
bounds which are less informative but conceptually much simpler
Comparison of remifentanil versus fentanyl general anesthesia for short outpatient urologic procedures
Study objectives. To compare the effect of remifentanil versus fentanyl isoflurane general anesthesia on Aldrete score, emergence, extubation and discharge times from the operating room (OR) and postanesthesia care unit (PACU) following short outpatient urologic procedures (panendoscopy and cystoscopy, bladder hydrodilatation, stent placement).
Patients and methods. 40 patients 18 years of age or older scheduled for short elective outpatient urological procedures with an expected duration of less than 30 minutes.
Following Institutional Review Board (IRB) approval and written informed consent, 40 American Society of Anesthesiologists (ASA) physical class 1-3 adult outpatients were enrolled and equally (n=20) randomized into remifentanil and fentanyl groups. Preoperatively, all subjects received intravenous (IV) midazolam 1-2 mg and were induced with propofol 2 mg/kg IV. Muscle relaxation was achieved with succinylcholine or rocuronium, followed by intubation. The remifentanil group received remifentanil 1 g/kg IV at induction with a maintenance dose of remifentanil 0.1 to 2 g/kg/min IV in the presence of 60% nitrous oxide (N2O)/40% oxygen (O2) and end-tidal isoflurane of 0.3 to 0.4% (for amnesia). The fentanyl group received fentanyl 2 g/kg IV at induction, maintenance dose of fentanyl 2 to 3 g/kg IV intermittent bolus, and 60% N2O/40% O2 with 2% end-tidal isoflurane. Muscle relaxation was reversed at the end of anesthesia as needed. Times for OR entry, emergence, extubation, total OR time (entry to exit) and PACU discharge time, as well as Aldrete scores at time of OR exit and PACU discharge were determined. Data was evaluated by ANOVA, t-test and Mann-Whitney tests. A p<0.05 value was considered statistically significant.
Results. There was no significant difference between groups in age, gender, weight, ASA class, PACU analgesic or antiemetic use, or times of emergence, extubation, OR exit and PACU discharge. There was a significant difference (p<0.05) in OR exit Aldrete score but not PACU discharge Aldrete score. No adverse events were noted.
Conclusions. While there was no difference between the remifentanil and fentanyl groups regarding recovery time from OR and PACU, remifentanil patients had significantly better OR exit Aldrete scores with less sedation upon arrival at phase I PACU recovery than the fentanyl group. This anesthesia technique may prove helpful for fast-track eligibility of these patients
Modality, Runs, Strings and Wavelets
The paper considers the problem of non-parametric regression with emphasis on controlling the number of local extrema. Two methods, the run method and the taut string-wavelet method, are introduced and analysed on standard test beds. It is shown that the number and location of local extreme values are consistently estimated.Rates of convergence are proved for both methods. The run method has a slow rate but can withstand blocks as well as a high proportion of isolated outliers. The rate of convergence of the taut string-wavelet method is almost optimal and the method is extremely sensitive being able to detect very low power peaks. Section 1 contains a short introduction with special reference to modality. The run method is described in Section 2 and the taut string-wavelet method in Section 3. Low power peaks are considered in Section 4. Section 5 contains a short conclusion and the proofs are given in Section 6
A high payload aerial platform for infrastructure repair and manufacturing
The use of aerial robots in construction is an area of general interest in the robotics community. Autonomous aerial systems have the potential to improve safety, efficiency and sustainability of industrial construction and repair processes. Several solutions have been deployed in this domain focusing on problems in aerial manipulation and control using existing aerial platforms which are not specialised for the specific challenges in operating on a construction site. This paper presents a new compact, high thrust aerial platform that can act as a modular, application agnostic base for demonstrating a wide variety of capabilities. The platform has been built and tested flying both with manual controls and autonomously in a motion tracking arena while carrying a payload of up to 7.3 kg with a maximum flight time between 10–34 mins (payload dependent). In the future, this platform will be combined with vision based tracking sensors, manipulators and other hardware to operate in and interact with an outdoor environment. Future applications may include manipulation of heavy objects, deposition of material and navigating confined spaces
Cosmological Parameter Extraction from the First Season of Observations with DASI
The Degree Angular Scale Interferometer (\dasi) has measured the power
spectrum of the Cosmic Microwave Background anisotropy over the range of
spherical harmonic multipoles 100<l<900. We compare this data, in combination
with the COBE-DMR results, to a seven dimensional grid of adiabatic CDM models.
Adopting the priors h>0.45 and 0.0<=tau_c<=0.4, we find that the total density
of the Universe Omega_tot=1.04+/-0.06, and the spectral index of the initial
scalar fluctuations n_s=1.01+0.08-0.06, in accordance with the predictions of
inflationary theory. In addition we find that the physical density of baryons
Omega_b.h^2=0.022+0.004-0.003, and the physical density of cold dark matter
Omega_cdm.h^2=0.14+/-0.04. This value of Omega_b.h^2 is consistent with that
derived from measurements of the primordial abundance ratios of the light
elements combined with big bang nucleosynthesis theory. Using the result of the
HST Key Project h=0.72+/-0.08 we find that Omega_t=1.00+/-0.04, the matter
density Omega_m=0.40+/-0.15, and the vacuum energy density
Omega_lambda=0.60+/-0.15. (All 68% confidence limits.)Comment: 7 pages, 4 figures, minor changes in response to referee comment
Confidence regions, non-parametric regression
In this paper we offer a unified approach to the problem of nonparametric
regression on the unit interval. It is based on a universal,
honest and non-asymptotic confidence region An which is defined by a
set of linear inequalities involving the values of the functions at the design
points. Interest will typically centre on certain simplest functions
in An where simplicity can be defined in terms of shape (number of local
extremes, intervals of convexity/concavity) or smoothness (bounds
on derivatives) or a combination of both. Once some form of regularization
has been decided upon the confidence region can be used
to provide honest non-asymptotic confidence bounds which are less
informative but conceptually much simpler. Although the procedure
makes no attempt to minimize any loss function such as MISE the
resulting estimates have optimal rates of convergence in the supremum
norm both for shape and smoothness regularization. We show
that rates of convergence can be misleading even for samples of size
n = 10^6 and propose a different form of asymptotics which allows
model complexity to increase with sample size
An aerial parallel manipulator with shared compliance
Accessing and interacting with difficult to reach surfaces at various orientations is of interest within a variety of industrial contexts. Thus far, the predominant robotic solution to such a problem has been to leverage the maneuverability of a fully actuated, omnidirectional aerial manipulator. Such an approach, however, requires a specialised system with a high relative degree of complexity, thus reducing platform endurance and real-world applicability. The work here presents a new aerial system composed of a parallel manipulator and conventional, underactuated multirotor flying base to demonstrate interaction with vertical and non-vertical surfaces. Our solution enables compliance to external disturbance on both subsystems, the manipulator and flying base, independently with a goal of improved overall system performance when interacting with surfaces. To achieve this behaviour, an admittance control strategy is implemented on various layers of the flying base's dynamics together with torque limits imposed on the manipulator actuators. Experimental evaluations show that the proposed system is compliant to external perturbations while allowing for differing interaction behaviours as compliance parameters of each subsystem are altered. Such capabilities enable an adjustable form of dexterity in completing sensor installation, inspection and aerial physical interaction tasks. A video of our system interacting with various surfaces can be found here: https://youtu.be/38neGb8-lXg
Cosmic Microwave Background Anisotropy Measurement From Python V
We analyze observations of the microwave sky made with the Python experiment
in its fifth year of operation at the Amundsen-Scott South Pole Station in
Antarctica. After modeling the noise and constructing a map, we extract the
cosmic signal from the data. We simultaneously estimate the angular power
spectrum in eight bands ranging from large (l ~ 40) to small (l ~ 260) angular
scales, with power detected in the first six bands. There is a significant rise
in the power spectrum from large to smaller (l ~ 200) scales, consistent with
that expected from acoustic oscillations in the early Universe. We compare this
Python V map to a map made from data taken in the third year of Python. Python
III observations were made at a frequency of 90 GHz and covered a subset of the
region of the sky covered by Python V observations, which were made at 40 GHz.
Good agreement is obtained both visually (with a filtered version of the map)
and via a likelihood ratio test.Comment: 28 pages, ApJ accepted, to appear v584 n2 ApJ Feb 20, 200
Anisotropy in the Cosmic Microwave Background at Degree Angular Scales: Python V Results
Observations of the microwave sky using the Python telescope in its fifth
season of operation at the Amundsen-Scott South Pole Station in Antarctica are
presented. The system consists of a 0.75 m off-axis telescope instrumented with
a HEMT amplifier-based radiometer having continuum sensitivity from 37-45 GHz
in two frequency bands. With a 0.91 deg x 1.02 deg beam the instrument fully
sampled 598 deg^2 of sky, including fields measured during the previous four
seasons of Python observations. Interpreting the observed fluctuations as
anisotropy in the cosmic microwave background, we place constraints on the
angular power spectrum of fluctuations in eight multipole bands up to l ~ 260.
The observed spectrum is consistent with both the COBE experiment and previous
Python results. There is no significant contamination from known foregrounds.
The results show a discernible rise in the angular power spectrum from large (l
~ 40) to small (l ~ 200) angular scales. The shape of the observed power
spectrum is not a simple linear rise but has a sharply increasing slope
starting at l ~ 150.Comment: 5 page
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