466 research outputs found
Hugo von Hofmannsthal und Julius Meier-Graefe : Briefwechsel
In einer kritischen Edition wurde hier der Briefwechsel zwischen Hugo von Hofmannsthal und Julius Meier-Graefe von 1917 bis 1929 in Herausgeberschaft von Ursula Renner abgedruckt, eingeleitet und kommentiert
Comparison of Aqwa, GL Rankine, Moses, Octopus, PDStrip and Wamit with model test results for cargo ship wave-induced motions in shallow water
A benchmarking study is carried out concerning wave induced ship motions in shallow water, predicted with commercially available codes AQWA, GL Rankine, MOSES, OCTOPUS, PDStrip and WAMIT. Comparison is made with experiments for three cargo ship models tested at Flanders Hydraulics Research. The same IGES models of the ship hulls were used in all codes to ensure consistent representation of the model geometry. The comparisons may be used to assess the suitability of each code for zero-speed applications such as berthed ship motions and under-keel clearance, as well as forward-speed applications such as under-keel clearance in navigation channels. Another, quickly developing, application area that requires analysis of seaway-induced ship motions in shallow water, is analysis of motions, accelerations and loads on cargo transport, installation and service vessels for offshore wind parks
Intravitreal Bevacizumab for Treatment of Refractory Central Serous Choroidoretinopathy
In a clinical case series, 5 patients with not-resolved central serous choroidoretinopathy (CSC) lasting more than 1 year received one intravitreal bevacizumab injection (IVB, 1.25 mg) injection. All patients underwent a through ophthalmic examination 1 day, 1 week, and 1, 2, and 6 months after the injection. Best corrected visual acuity (BCVA) and central macular thickness were compared before and after treatment by optical coherence tomography. Mean BCVA was improved significantly (p = 0.020) from 0.60 ± 0.25 to 0.50 ± 0.18 and 0.29 ± 0.19 logarithm of minimum angle of resolution at 6 and 18 weeks, respectively. Central macular thickness was also decreased significantly (p = 0.010) from 370 ± 65 to 208 ± 23 µm at 4 months. No recurrence was occurred during follow-up. IVB injection may have beneficial effect in the treatment of refractory CSC
Why did Donders, after describing pseudotorsion, deny the existence of ocular counterrolling together with Ruete, Volkmann, von Graefe and von Helmholtz, until Javal reconfirmed its existence?
After the rapid spread of strabismus surgery by total tenotomy, which had been proposed by the orthopedist Louis Stromeyer from Göttingen in 1838 and performed by the plastic surgeon Johann Friedrich Dieffenbach on October 26th and by the ophthalmologist Florent Cunier on October 29th, 1839, brilliant researchers studied the physiology of eye movements, resulting in the laws by Franciscus Cornelis Donders on pseudotorsion in tertiary positions of gaze and by Johann Benedict Listing that each eye position can be reached by rotation about an axis perpendicular to the primary and the new position of gaze. John Hunter had first described ocular counterrolling (OCR) with head tilt in 1786. The anatomist Alexander Friedrich von Hueck inferred from anatomical studies, however, that up to 28.6° OCR would be possible onhead-tilt to right or left shoulder in 1838, and estimated his own OCR seen in a mirror at approximately 25°. Donders, Christian Georg Theodor Ruete, Alfred Wilhelm Volkmann, Albrecht von Graefe and Hermann von Helmholtz subsequently denied the existence of OCR for many years and thought that only pseudotorsion existed. Louis Emile Javal had myopia and astigmatism, and he re-established the existence of OCR in 1867 when he noticed that, on head tilt to either shoulder, the axis of astigmatism of his eyes no longer coincided with the axis of astigmatism of his glasses
On the construction of pseudo-hermitian quantum system with a pre-determined metric in the Hilbert space
A class of pseudo-hermitian quantum system with an explicit form of the
positive-definite metric in the Hilbert space is presented. The general method
involves a realization of the basic canonical commutation relations defining
the quantum system in terms of operators those are hermitian with respect to a
pre-determined positive definite metric in the Hilbert space. Appropriate
combinations of these operators result in a large number of pseudo-hermitian
quantum systems admitting entirely real spectra and unitary time evolution. The
examples considered include simple harmonic oscillators with complex angular
frequencies, Stark(Zeeman) effect with complex electric(magnetic) field,
non-hermitian general quadratic form of N boson(fermion) operators, symmetric
and asymmetric XXZ spin-chain in complex magnetic field, non-hermitian
Haldane-Shastry spin-chain and Lipkin-Meshkov-Glick model.Comment: 29 pages, revtex, minor changes, version to appear in Journal of
Physics A(v3
Metric operators for non-Hermitian quadratic su(2) Hamiltonians
A class of non-Hermitian quadratic su(2) Hamiltonians having an anti-linear
symmetry is constructed. This is achieved by analysing the possible symmetries
of such systems in terms of automorphisms of the algebra. In fact, different
realisations for this type of symmetry are obtained, including the natural
occurrence of charge conjugation together with parity and time reversal. Once
specified the underlying anti-linear symmetry of the Hamiltonian, the former,
if unbroken, leads to a purely real spectrum and the latter can be mapped to a
Hermitian counterpart by, amongst other possibilities, a similarity
transformation. Here, Lie-algebraic methods which were used to investigate the
generalised Swanson Hamiltonian are employed to identify the class of quadratic
Hamiltonians that allow for such a mapping to the Hermitian counterpart.
Whereas for the linear su(2) system every Hamiltonian of this type can be
mapped to a Hermitian counterpart by a transformation which is itself an
exponential of a linear combination of su(2) generators, the situation is more
complicated for quadratic Hamiltonians. Therefore, the possibility of more
elaborate similarity transformations, including quadratic exponents, is also
explored in detail. The existence of finite dimensional representations for the
su(2) Hamiltonian, as opposed to the su(1,1) studied before, allows for
comparison with explicit diagonalisation results for finite matrices. Finally,
the similarity transformations constructed are compared with the analogue of
Swanson's method for exact diagonalsation of the problem, establishing a simple
relation between both approaches.Comment: 25 pages, 6 figure
Fast rates of subduction erosion along the Costa Rica Pacific margin: implications for non-steady rates of crustal recycling at subduction zones
At least since the middle Miocene (∼16 Ma), subduction erosion has been the dominant process controlling the tectonic evolution of the Pacific margin of Costa Rica. Ocean Drilling Program Site 1042 recovered 16.5 Ma nearshore sediment at ∼3.9 km depth, ∼7 km landward of the trench axis. The overlying Miocene to Quaternary sediment contains benthic foraminifera documenting margin subsidence from upper bathyal (∼200 m) to abyssal (∼2000 m) depth. The rate of subsidence was low during the early to middle Miocene but increased sharply in the late Miocene-early Pliocene (5–6.5 Ma) and at the Pliocene-Pleistocene boundary (2.4 Ma). Foraminifera data, bedding dip, and the geometry of slope sediment indicate that tilting of the forearc occurred coincident with the onset of rapid late Miocene subsidence. Seismic images show that normal faulting is widespread across the continental slope; however, extension by faulting only accounts for a minor amount of the post-6.5 Ma subsidence. Basal tectonic erosion is invoked to explain the subsidence. The short-term rate of removal of rock from the forearc is about 107–123 km3 Myr−1 km−1. Mass removal is a nonsteady state process affecting the chemical balance of the arc: the ocean sediment input, with the short-term erosion rate, is a factor of 10 smaller than the eroded mass input. The low 10Be concentration in the volcanic arc of Costa Rica could be explained by dilution with eroded material. The late Miocene onset of rapid subsidence is coeval with the arrival of the Cocos Ridge at the subduction zone. The underthrusting of thick and thermally younger ocean crust decreased the subduction angle of the slab along a large segment of the margin and changed the dynamic equilibrium of the margin taper. This process may have induced the increase in the rate of subduction erosion and thus the recycling of crustal material to the mantle
Fast rates of subduction erosion along the Costa Rica Pacific margin: Implications for nonsteady rates of crustal recycling at subduction zones
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