BACKGROUND The aim of total knee surgery is to provide patients with end-stage osteoarthritis of the knee with both pain relief and a functional range of motion with a securely fixed prosthesis for the long term. Many types of implants are designed to achieve these goals. Only clinical outcome studies are able to substantiate the superiority of one design over another. Our primary research ques...

3. The Auditory Image ....................................................................................557 3.1 The Temporal Integration Problem in Audition .................................. 557 3.2 Quantised Temporal Integration ........................................................ 558 3.3 The Trigger Mechanism .................................................................... 560 3.4 ...

Infrared images of the Q 0957+561 gravitational lens obtained with the Hubble Space Telescope show two large (∼5 ′′) lensed images of the z s = 1.41 quasar host galaxy. Parts of the host galaxy are doubly-imaged like the quasar, while other parts are quadruply-imaged. The distortions of the host galaxy offer the best probe yet of the global structure of the lensing potential, which is essential...

In the mid-1980s, a citizens' organization in New Jersey --Clean Ocean Action, led by Cindy Zipf --launched an aggressive campaign to protect the oceans from the dumping of toxic sewage sludge. They were up against extraordinary power: U.S. Environmental Protection Agency (EPA) opposed them; New York and New Jersey environmental officials opposed them; nearly every municipal government opposed ...

0957+561 is the first gravitational lens system to be discovered and first for which a time delay was measured. Because the system is unusually rich in observables such as image positions, fluxes, VLBI structure, and polarization it has been modelled quite extensively. However, since it resides in a cluster providing substantial convergence, the velocity dispersion of the lensing galaxy is an i...

Proof. Suppose that φ; Z/nZ → Z/nZ is an automorphism with φ(1) = a. By the homomorphism property we have φ(x) = φ(1 + · · · + 1) = φ(1) + · · · + φ(1) = a + · · · + a = ax. Thus the image of φ is the (additive) cyclic subgroup 〈a〉 ≤ Z/nZ. Then since φ is surjective we must have 〈a〉 = Z/nZ. By the Lemma, this happens if and only if a and n are coprime, i.e. a ∈ (Z/nZ)×, in which case the map φ(...

We report the detection of the lens cluster of the gravitational lens (GL) system Q0957+561 from a deep observation with the Advanced CCD Imaging Spectrometer on-board the Chandra X-ray Observatory. Intracluster X-ray emission is found to be centered 4 ′′ .3 north of image B, nearer than previous estimates. Its spectrum can be modeled well with a thermal plasma model consistent with the emissio...

In many applications of ageand size-structured population models, there is an interest in obtaining good approximations of total population numbers rather than of their densities. Therefore, it is reasonable in such cases to solve numerically not the PDE model equations themselves, but rather their integral equivalents. For this purpose quadrature formulae are used in place of the integrals. Si...