24,763 research outputs found
Norwegian Aerospace Activities: an Overview
Excerpts from a Governmental Investigation concerning Norwegian participation in the European Space Organization (ESA) is presented. The implications and advantages of such a move and a suggestion for the reorganization of Norwegian Aerospace activity is given
Polar communications: Status and recommendations. Report of the Science Working Group
The capabilities of the existing communication links within the polar regions, as well as between the polar regions and the continental United States, are summarized. These capabilities are placed in the context of the principal scientific disciplines that are active in polar research, and in the context of how scientists both utilize and are limited by present technologies. Based on an assessment of the scientific objectives potentially achievable with improved communication capabilities, a list of requirements on and recommendations for communication capabilities necessary to support polar science over the next ten years is given
On non-normality and classification of amplification mechanisms in stability and resolvent analysis
We seek to quantify non-normality of the most amplified resolvent modes and
predict their features based on the characteristics of the base or mean
velocity profile. A 2-by-2 model linear Navier-Stokes (LNS) operator
illustrates how non-normality from mean shear distributes perturbation energy
in different velocity components of the forcing and response modes. The inverse
of their inner product, which is unity for a purely normal mechanism, is
proposed as a measure to quantify non-normality. In flows where there is
downstream spatial dependence of the base/mean, mean flow advection separates
the spatial support of forcing and response modes which impacts the inner
product. Success of mean stability analysis depends on the normality of
amplification. If the amplification is normal, the resolvent operator written
in its dyadic representation reveals that the adjoint and forward stability
modes are proportional to the forcing and response resolvent modes. If the
amplification is non-normal, then resolvent analysis is required to understand
the origin of observed flow structures. Eigenspectra and pseudospectra are used
to characterize these phenomena. Two test cases are studied: low Reynolds
number cylinder flow and turbulent channel flow. The first deals mainly with
normal mechanisms and quantification of non-normality using the inverse inner
product of the leading forcing and response modes agrees well with the product
of the resolvent norm and distance between the imaginary axis and least stable
eigenvalue. In turbulent channel flow, structures result from both normal and
non-normal mechanisms. Mean shear is exploited most efficiently by stationary
disturbances while bounds on the pseudospectra illustrate how non-normality is
responsible for the most amplified disturbances at spatial wavenumbers and
temporal frequencies corresponding to well-known turbulent structures
The Continued Relevance of the Irrelevance-of-Motive Maxim
The irrelevance-of-motive maxim-the longstanding principle that a defendant\u27s motives are irrelevant to criminal liability-has come under attack. Critics of this maxim claim that motives, under any plausible conception of the term, are in fact relevant in the criminal law. According to these critics, the only way to defend the truth of the irrelevance-of-motive maxim is to render it true by definition, by defining motive as the subcategory of intentions that are irrelevant to criminal liability. This Note defends the irrelevance-of-motive maxim by applying a plausible conception of motive that conforms to the historical meaning of the term. With the proper definition in place, the irrelevance-of-motive maxim can be understood as stating a valid principle of criminal law, defied only by the advent of a certain kind of bias crime legislation
Smart helmet: wearable multichannel ECG & EEG
Modern wearable technologies have enabled continuous recording of vital signs, however, for activities such as cycling, motor-racing, or military engagement, a helmet with embedded sensors would provide maximum convenience and the opportunity to monitor simultaneously both the vital signs and the electroencephalogram (EEG). To this end, we investigate the feasibility of recording the electrocardiogram (ECG), respiration, and EEG from face-lead locations, by embedding multiple electrodes within a standard helmet. The electrode positions are at the lower jaw, mastoids, and forehead, while for validation purposes a respiration belt around the thorax and a reference ECG from the chest serve as ground truth to assess the performance. The within-helmet EEG is verified by exposing the subjects to periodic visual and auditory stimuli and screening the recordings for the steady-state evoked potentials in response to these stimuli. Cycling and walking are chosen as real-world activities to illustrate how to deal with the so-induced irregular motion artifacts, which contaminate the recordings. We also propose a multivariate R-peak detection algorithm suitable for such noisy environments. Recordings in real-world scenarios support a proof of concept of the feasibility of recording vital signs and EEG from the proposed smart helmet
Alienating Aliens: Equal Protection Violations in the Structures of State Public-Benefit Schemes
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Secondary acute lymphoblastic leukemia is a distinct clinical entity with prognostic significance.
The effect of prior malignancy on the risk of developing, and prognosis of, acute lymphoblastic leukemia (ALL) is unknown. This observational study utilized the California Cancer Registry to estimate the risk of developing ALL after a prior malignancy using standardized incidence ratios (SIRs, 95% confidence intervals). ALL occurring after a malignancy with an SIR>1 (increased-risk (IR) malignancies) was considered secondary ALL (s-ALL). Adjusted hazard ratios (aHRs, 95% confidence intervals) compared the effect of s-ALL with de novo ALL on overall survival. A total of 14 481 patients with ALL were identified (1988-2012) and 382 (3%) had a known prior malignancy. Any prior malignancy predisposed patients to developing ALL: SIR 1.62 (1.45-1.79). Hematologic malignancies (SIR 5.57, 4.38-6.98) and IR-solid tumors (SIR 2.11, 1.73-2.54) increased the risk of developing ALL. s-ALL increased the risk of death compared with de novo ALL (aHR 1.38 (1.16-1.63)) and this effect was more pronounced among younger patients (age<40 years: aHR 4.80 (3.15-7.30); age⩾40 years: aHR 1.40 (1.16-1.69)) (interaction P<0.001). This population-based study demonstrates that s-ALL is a distinct entity that occurs after specific malignancies and carries a poor prognosis compared with de novo ALL, particularly among patients <40 years of age
Surgery and the Spectrum of the Dirac Operator
We show that for generic Riemannian metrics on a simply-connected closed spin
manifold of dimension at least 5 the dimension of the space of harmonic spinors
is no larger than it must be by the index theorem. The same result holds for
periodic fundamental groups of odd order.
The proof is based on a surgery theorem for the Dirac spectrum which says
that if one performs surgery of codimension at least 3 on a closed Riemannian
spin manifold, then the Dirac spectrum changes arbitrarily little provided the
metric on the manifold after surgery is chosen properly.Comment: 23 pages, 4 figures, to appear in J. Reine Angew. Mat
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