Inversion of low-frequency subsurface data in a finite-depth ocean

AbstractLet:[▿2+k2+k2v(x)]u=−δ(x−y) in L=R2 × [0,h],u= 0 at x3 = 0, ux3 = 0 at x3 = h, u(x,y,k) satisfies the limiting absorption principle. Letu(x,y,k) be known for all x,y∈ P ≔ {x:x3 = d}, where 0< d<h is a small fixed number (subsurface data), and allk∈ (0,k0),k0 > 0 is a small number. These data determine v(x) uniquely and an analytical procedure is given for finding v(x) given the above data. It is assumed that v(x), the inhomogeneity in the refraction coefficient (of the ocean of depth h), is an arbitrary compactly supported square integrable function

Comment on "Evolution of a Quasi-Stationary State"

Approximately forty years ago it was realized that the time development of decaying systems might not be precisely exponential. Rolf Winter (Phys. Rev. {\bf 123}, 1503 (1961)) analyzed the simplest nontrivial system - a particle tunneling out of a well formed by a wall and a delta-function. He calculated the probability current just outside the well and found irregular oscillations on a short time scale followed by an exponential decrease followed by more oscillations and finally by a decrease as a power of the time. We have reanalyzed this system, concentrating on the survival probability of the particle in the well rather than the probability current, and find a different short time behavior.Comment: 8 pages, 6 figures, RevTex

Charged Higgs bosons in the Next-to MSSM (NMSSM)

The charged Higgs boson decays $H^\pm\to W^\pm A_1$ and $H^\pm\to W^\pm h_i$ are studied in the framework of the next-to Minimal Supersymmetric Standard Model (NMSSM). It is found that the decay rate for $H^\pm\to W^\pm A_1$ can exceed the rates for the $\tau^\pm\nu$ and $tb$ channels both below and above the top-bottom threshold. The dominance of $H^\pm\to W^\pm A_1$ is most readily achieved when $A_1$ has a large doublet component and small mass. We also study the production process $pp\to H^\pm A_1$ at the LHC followed by the decay $H^\pm\to W^\pm A_1$ which leads to the signature $W^\pm A_1 A_1$. We suggest that $p p\to H^\pm A_1$ is a promising discovery channel for a light charged Higgs boson in the NMSSM with small or moderate $\tan\beta$ and dominant decay mode $H^\pm \to W^\pm A_1$. This $W^\pm A_1 A_1$ signature can also arise from the Higgsstrahlung process $pp\to W^\pm h_1$ followed by the decay $h_1\to A_1 A_1$. It is shown that there exist regions of parameter space where these processes can have comparable cross sections and we suggest that their respective signals can be distinguished at the LHC by using appropriate reconstruction methods.Comment: 20 pages, 22 eps figures, more reference adde

X-ray and neutron diffraction studies of coupled structural phase transitions in DyBaCo2_{2}O5.5_{5.5}

A structural transition at $T\approx 322$ K from the $Pmmm$ to $Pmma$ phase is found to coincide with an anomaly of resistivity. Another structural phase transition doubling the lattice parameter $c$, which has been postulated earlier to accompany a low-temperature magnetic transition in TbBaCo$_{2}$O$_{5.5}$, is observed in a single crystal DbBaCo$_{2}$O$_{5.5}$ by means of the X-ray and neutron diffraction. The low temperature phase does not belong to the space group $Pcca$ that has been chosen earlier as the highest subgroup of the $Pmma$. The transition is of the first order with the temperature hysteresis, between $T\approx 100$ and $T\approx 200$ K, which probably explains anomalous magnetic properties in this temperature range.Comment: 6 pages, 4 figure

High TcT_c Superconductivity, Skyrmions and the Berry Phase

It is here pointed out that the antiferromagnetic spin fluctuation may be associated with a gauge field which gives rise to the antiferromagnetic ground state chirality. This is associated with the chiral anomaly and Berry phase when we consider the two dimensional spin system on the surface of a 3D sphere with a monopole at the centre. This realizes the RVB state where spinons and holons can be understood as chargeless spins and spinless holes attached with magnetic flux. The attachment of the magnetic flux of the charge carrier suggest, that this may be viewed as a skyrmion. The interaction of a massless fermion representing a neutral spin with a gauge field along with the interaction of a spinless hole with the gauge field enhances the antiferromagnetic correlation along with the pseudogap at the underdoped region. As the doping increases the antiferromagnetic long range order disappears for the critical doping parameter $\delta_{sc}$. In this framework, the superconducting pairing may be viewed as caused by skyrmion-skyrmion bound states.Comment: 10 pages, accepted in Phys. Rev.

Large mass splittings between charged and neutral Higgs bosons in the MSSM

We show that large ($> 100$ GeV) mass splittings between the charged Higgs boson ($H^\pm$) and the neutral Higgs bosons ($H^0$ and $A^0$) are possible in the Minimal Supersymmetric Standard Model (MSSM). Such splittings occur when the $\mu$ parameter is considerably larger than the common SUSY scale, $M_{SUSY}$, and have significant consequences for MSSM Higgs searches at future colliders.Comment: 11 pages, LaTex, 5 figures, version to appear in Phys. Lett.

Temporal variations in English Populations of a forest insect pest, the green spruce aphid (Elatobium abietinum), associated with the North Atlantic Oscillation and global warming

Based on an exceptionally long modern ecological dataset (41 years), it has been possible to show that warm weather in England associated with a positive North Atlantic Oscillation (NAO) index causes the spring migration of the green spruce aphid (Elatobium abietinum), a pest species of spruce trees (Picea) to start earlier, continue for longer and contain more aphids. An upward trend in the NAO index during the period 1966-2006 is associated with an increasing population size of E. abietinum. It is important to understand the mechanisms behind the population fluctuations, because this aphid causes considerable damage to Picea plantations. Present day weather associated fluctuations in forest insect pests may be useful analogues in understanding past pest outbreaks in forests

Translation, Validity, and Reliability of the Dutch Anterior Cruciate Ligament–Quality of Life Questionnaire

Background: The Anterior Cruciate Ligament–Quality of Life (ACL-QoL) questionnaire is a valid and reliable injury-specific instrument to assess the impact of an ACL rupture on the daily life of a patient. Purpose: To translate the ACL-QoL into Dutch (ACL-QoL-NL) and to study its psychometric properties in patients with an ACL rupture. Study Design: Cohort study (diagnosis); Level of evidence, 2. Methods: The original ACL-QoL questionnaire was translated from English to Dutch according to international guidelines. The study population consisted of 122 patients with a confirmed ACL rupture who completed the ACL-QoL-NL as well as 4 questionnaires: the International Knee Documentation Committee subjective score, Knee injury and Osteoarthritis Outcome Score, 36-item Short Form Health Survey, and Lysholm Knee Score. We determined the internal consistency, construct validity, and prevalence of floor and ceiling effects of the ACL-QoL-NL total score as well as its 5 subscales. To determine test-retest reliability, we analyzed the data of 68 patients who had a stable knee condition and who completed the ACL-QoL-NL a second time after a 2-week interval. Results: The confirmatory factor analysis showed that the original structure of the ACL-QoL-NL was confirmed, except for 4 of 31 items. Internal consistency of the total scale and all 5 subscales was good. More than 75% of the predefined hypotheses on the correlations between the ACL-QoL-NL and the 4 questionnaires were met, indicating good construct validity. No significant floor or ceiling effects were observed. Test-retest reliability was good, and no systematic bias between test and retest was found. Standard error of measurement for the total score was 4.8 points out of 100, and the smallest detectable changes at the group and individual levels were 1.6 and 13.2 points, respectively. Conclusion: The ACL-QoL-NL questionnaire was successfully translated from English to Dutch and demonstrated good internal consistency, validity, and reliability, with no presence of floor or ceiling effects