@article{18369, author = {Bronstein, Michael M. and Bronstein, Alexander}, issn = {0028-0836}, journal = {Nature}, number = {6917}, pages = {739--739}, publisher = {Springer Nature}, title = {{Biometrics was no match for hair-raising tricks}}, doi = {10.1038/420739a}, volume = {420}, year = {2002}, } @inproceedings{18382, abstract = {Detection of high-energy photons emitted as the result of positron decay is one of the most important low-level stages in PET imaging. In this paper we consider a detector based on the Anger scintillation camera. Incident high-energy gamma quanta, generated due to positron decay, produce scintillation effect in the crystal. As a result, a shower of low energy photons in the visible and UV spectra is emitted. These photons are collected by an array of photo-multipliers (PMTs), optically coupled to the scintillation crystal, and invoke electric impulses in them. The PMT responses are utilized in estimation of the scintillation point coordinates. Our work incorporates side information on the photon incidence angle into the process of position estimation. We use localized, asymptotically optimal, nonlinear estimators, implemented by feedforward and radial basis function (RBF) neural networks. As a byproduct, we get accurate position estimation over the entire area of the detector including the edges. This is difficult to obtain with centroid arithmetic algorithms. We present a comparison of algorithms on a Monte Carlo simulation and discuss the prospects for practical implementation.}, author = {Bronstein, Alexander and Bronstein, M.M. and Zibulevsky, M. and Zeevi, Y.Y.}, booktitle = {The 22nd Convention on Electrical and Electronics Engineers in Israel}, isbn = {0780376935}, location = {Tel-Aviv, Israel}, pages = {341--344}, publisher = {IEEE}, title = {{Optimal non-linear line-of-flight estimation in positron emission tomography}}, doi = {10.1109/eeei.2002.1178493}, volume = {2002-January}, year = {2002}, } @inproceedings{18383, author = {Bronstein, M.M. and Bronstein, Alexander and Zibulevsky, M. and Azhari, H.}, booktitle = {The 22nd Convention on Electrical and Electronics Engineers in Israel}, isbn = {0780376935}, location = {Tel-Aviv, Israel}, pages = {345--347}, publisher = {IEEE}, title = {{Application of the NUFFT for reconstruction problems in diffraction tomography}}, doi = {10.1109/eeei.2002.1178495}, volume = {2002-January}, year = {2002}, } @inproceedings{18404, abstract = {We consider detection of high-energy photons in PET using thick scintillation crystals. Parallax effect and multiple Compton interactions in this type of crystals significantly reduce the accuracy of conventional detection methods. In order to estimate the scintillation point coordinates based on photomultiplier responses, we use asymptotically optimal nonlinear techniques, implemented by feed-forward neural networks, radial basis functions (RBF) networks, and neuro-fuzzy systems. Incorporation of information about angles of incidence of photons, significantly improves accuracy of estimation. The proposed estimators are fast enough to perform detection, using conventional computers.}, author = {Bronstein, Alexander and Bronstein, M. and Zibulevsky, M. and Zeevi, Y.Y.}, booktitle = {Proceedings IEEE International Symposium on Biomedical Imaging}, isbn = {078037584X}, location = {Washington, DC, United States}, pages = {541--544}, publisher = {IEEE}, title = {{Optimal nonlinear estimation of photon coordinates in PET}}, doi = {10.1109/isbi.2002.1029314}, volume = {2002-January}, year = {2002}, } @inproceedings{18405, abstract = {We show an iterative reconstruction framework for diffraction ultrasound tomography. The use of broadband illumination allows the number of projections to be reduced significantly compared to straight ray tomography. The proposed algorithm makes use of fast forward non-uniform Fourier transform (NUFFT) for iterative Fourier inversion. Incorporation of total variation regularization allows noise and Gibbs phenomena to be reduced whilst preserving the edges.}, author = {Bronstein, M. and Bronstein, Alexander and Zibulevsky, M.}, booktitle = {Proceedings IEEE International Symposium on Biomedical Imaging}, isbn = {078037584X}, location = {Washington, DC, United States}, pages = {633--636}, publisher = {IEEE}, title = {{Iterative reconstruction in diffraction tomography using nonuniform fast Fourier transform}}, doi = {10.1109/isbi.2002.1029337}, volume = {2002-January}, year = {2002}, } @article{18409, abstract = {We show an iterative reconstruction framework for diffraction ultrasound tomography. The use of broad-band illumination allows significant reduction of the number of projections compared to straight ray tomography. The proposed algorithm makes use of forward nonuniform fast Fourier transform (NUFFT) for iterative Fourier inversion. Incorporation of total variation regularization allows the reduction of noise and Gibbs phenomena while preserving the edges. The complexity of the NUFFT-based reconstruction is comparable to the frequency-domain interpolation (gridding) algorithm, whereas the reconstruction accuracy (in sense of the L/sup 2/ and the L/sup /spl infin// norm) is better.}, author = {Bronstein, M.M. and Bronstein, Alexander and Zibulevsky, M. and Azhari, H.}, issn = {0278-0062}, journal = {IEEE Transactions on Medical Imaging}, number = {11}, pages = {1395--1401}, publisher = {Institute of Electrical and Electronics Engineers}, title = {{Reconstruction in diffraction ultrasound tomography using nonuniform FFT}}, doi = {10.1109/tmi.2002.806423}, volume = {21}, year = {2002}, } @article{12659, abstract = {For many years considerable efforts have been put into investigating and modelling hydrological processes of mountainous catchments. On the one hand, the complexity and intrinsically high variability of the involved processes as well as insufficient knowledge of the underlying physical mechanisms still induce large uncertainties in understanding observed phenomena and predicting the behaviour of the system. On the other hand, the demand for models that are able to simulate mountainous water resource systems is increasing because of the needs related to both water exploitation and water conservation, which clearly call for an integrated vision and modelling of these systems. Accordingly, this paper moves from a brief survey of the most significant achievements in mountain hydrology to discuss what could be future challenging issues related to the broader spectrum of questions, which hydrologic modelling of mountainous river systems may face in the next decades. Firstly, reference is made to existing methodologies for modelling alpine water systems, focussing on some specific aspects that provide a basis for the discussion of the weaknesses and perspectives of present simulation tools. The future is thus discussed, delineating some of the research challenges that may foster a comprehensive and integrated vision of water related issues in mountainous regions.}, author = {Burlando, Paolo and Pellicciotti, Francesca and Strasser, Ulrich}, issn = {2224-7955}, journal = {Hydrology Research}, number = {1}, pages = {47--74}, publisher = {IWA Publishing}, title = {{Modelling mountainous water systems between learning and speculating looking for challenges}}, doi = {10.2166/nh.2002.0004}, volume = {33}, year = {2002}, } @article{204, abstract = {Let k⩾5 be an integer, and let x⩾1 be an arbitrary real number. We derive a bound[Formula presented] for the number of positive integers less than or equal to x which can be represented as a sum of two non-negative coprime kth powers, in essentially more than one way.}, author = {Browning, Timothy D}, issn = {0022-314X}, journal = {Journal of Number Theory}, number = {2}, pages = {293 -- 318}, publisher = {Academic Press}, title = {{Equal Sums of Two kth Powers}}, doi = {10.1006/jnth.2002.2800}, volume = {96}, year = {2002}, } @article{11123, abstract = {The small GTPase Ran is a key regulator of nucleocytoplasmic transport during interphase. The asymmetric distribution of the GTP-bound form of Ran across the nuclear envelope — that is, large quantities in the nucleus compared with small quantities in the cytoplasm — determines the directionality of many nuclear transport processes. Recent findings that Ran also functions in spindle formation and nuclear envelope assembly during mitosis suggest that Ran has a general role in chromatin-centred processes. Ran functions in these events as a signal for chromosome position.}, author = {HETZER, Martin W and Gruss, Oliver J. and Mattaj, Iain W.}, issn = {1476-4679}, journal = {Nature Cell Biology}, keywords = {Cell Biology}, number = {7}, pages = {E177--E184}, publisher = {Springer Nature}, title = {{The Ran GTPase as a marker of chromosome position in spindle formation and nuclear envelope assembly}}, doi = {10.1038/ncb0702-e177}, volume = {4}, year = {2002}, } @article{11124, abstract = {Ran GTPase plays important roles in nucleocytoplasmic transport in interphase [1, 2] and in both spindle formation and nuclear envelope (NE) assembly during mitosis [3, 4, 5]. The latter functions rely on the presence of high local concentrations of GTP-bound Ran near mitotic chromatin [3, 4, 5]. RanGTP localization has been proposed to result from the association of Ran's GDP/GTP exchange factor, RCC1, with chromatin [6, 7, 8, 9], but Ran is shown here to bind directly to chromatin in two modes, either dependent or independent of RCC1, and, where bound, to increase the affinity of chromatin for NE membranes. We propose that the Ran binding capacity of chromatin contributes to localized spindle and NE assembly.}, author = {Bilbao-Cortés, Daniel and HETZER, Martin W and Längst, Gernot and Becker, Peter B. and Mattaj, Iain W.}, issn = {0960-9822}, journal = {Current Biology}, keywords = {General Agricultural and Biological Sciences, General Biochemistry, Genetics and Molecular Biology}, number = {13}, pages = {1151--1156}, publisher = {Elsevier BV}, title = {{Ran binds to chromatin by two distinct mechanisms}}, doi = {10.1016/s0960-9822(02)00927-2}, volume = {12}, year = {2002}, } @inbook{2338, abstract = {Now that the low temperature properties of quantum-mechanical many-body systems (bosons) at low density, ρ, can be examined experimentally it is appropriate to revisit some of the formulas deduced by many authors 4-5 decades ago. For systems with repulsive (i.e. positive) interaction potentials the experimental low temperature state and the ground state are effectively synonymous -- and this fact is used in all modeling. In such cases, the leading term in the energy/particle is 2πℏ2aρ/m where a is the scattering length of the two-body potential. Owing to the delicate and peculiar nature of bosonic correlations (such as the strange N7/5 law for charged bosons), four decades of research failed to establish this plausible formula rigorously. The only previous lower bound for the energy was found by Dyson in 1957, but it was 14 times too small. The correct asymptotic formula has recently been obtained by us and this work will be presented. The reason behind the mathematical difficulties will be emphasized. A different formula, postulated as late as 1971 by Schick, holds in two-dimensions and this, too, will be shown to be correct. With the aid of the methodology developed to prove the lower bound for the homogeneous gas, two other problems have been successfully addressed. One is the proof by us that the Gross-Pitaevskii equation correctly describes the ground state in the `traps' actually used in the experiments. For this system it is also possible to prove complete Bose condensation, as we have shown. Another topic is a proof that Foldy's 1961 theory of a high density Bose gas of charged particles correctly describes its ground state energy.}, author = {Lieb, Élliott and Solovej, Jan and Seiringer, Robert and Yngvason, Jakob}, booktitle = {Current Developments in Mathematics, 2001}, isbn = {9781571461018}, pages = {131 -- 178}, publisher = {International Press}, title = {{The ground state of the Bose gas}}, doi = {10.48550/arXiv.math-ph/0204027}, year = {2002}, } @inproceedings{2339, author = {Robert Seiringer}, editor = {Weder, Richardo and Exner, Pavel and Grébert, Benoit}, pages = {281 -- 286}, publisher = {World Scientific Publishing}, title = {{Symmetry breaking in a model of a rotating Bose gas}}, doi = {10.1090/conm/307}, volume = {307}, year = {2002}, } @article{2349, abstract = {The Bose-Einstein condensation (BEC) of the ground state of bosonic atoms in a trap was discussed. The BEC was proved for bosons with two-body repulsive interaction potentials in the dilute limit, starting from the basic Schrodinger equation. The BEC was 100% into the state which minimized the Gross-Pitaevskii energy functional. The analysis also included rigorous proof of BEC in a physically realistic, continuum model.}, author = {Lieb, Élliott H and Robert Seiringer}, journal = {Physical Review Letters}, number = {17}, pages = {1704091 -- 1704094}, publisher = {American Physical Society}, title = {{Proof of Bose-Einstein condensation for dilute trapped gases}}, doi = {10.1103/PhysRevLett.88.170409}, volume = {88}, year = {2002}, } @article{2350, abstract = {Using the Pauli-Fierz model of non-relativistic quantum electrodynamics, we calculate the binding energy of an electron in the field of a nucleus of charge Z and in presence of the quantized radiation field. We consider the case of small coupling constant α, but fixed Zα and ultraviolet cut-off Λ. We prove that after renormalizing the mass the binding energy has, to leading order in α, a finite limit as Λ goes to infinity; i.e., the cut-off can be removed. The expression for the ground state energy shift thus obtained agrees with Bethe's formula for small values of Zα, but shows a different behavior for bigger values.}, author = {Hainzl, Christian and Seiringer, Robert}, issn = {1095-0761}, journal = {Advances in Theoretical and Mathematical Physics}, number = {5}, pages = {847 -- 871}, publisher = {International Press}, title = {{Mass renormalization and energy level shift in non-relativistic QED}}, doi = {10.4310/ATMP.2002.v6.n5.a3}, volume = {6}, year = {2002}, } @article{2351, abstract = {We study the Gross-Pitaevskii functional for a rotating two-dimensional Bose gas in a trap. We prove that there is a breaking of the rotational symmetry in the ground state; more precisely, for any value of the angular velocity and for large enough values of the interaction strength, the ground state of the functional is not an eigenfunction of the angular momentum. This has interesting consequences on the Bose gas with spin; in particular, the ground state energy depends non-trivially on the number of spin components, and the different components do not have the same wave function. For the special case of a harmonic trap potential, we give explicit upper and lower bounds on the critical coupling constant for symmetry breaking.}, author = {Robert Seiringer}, journal = {Communications in Mathematical Physics}, number = {3}, pages = {491 -- 509}, publisher = {Springer}, title = {{Gross-Pitaevskii theory of the rotating Bose gas}}, doi = {10.1007/s00220-002-0695-2}, volume = {229}, year = {2002}, } @article{2352, abstract = {We present a generalization of the Fefferman-de la Llave decomposition of the Coulomb potential to quite arbitrary radial functions V on ℝn going to zero at infinity. This generalized decomposition can be used to extend previous results on N-body quantum systems with Coulomb interaction to a more general class of interactions. As an example of such an application, we derive the high density asymptotics of the ground state energy of jellium with Yukawa interaction in the thermodynamic limit, using a correlation estimate by Graf and Solovej.}, author = {Hainzl, Christian and Robert Seiringer}, journal = {Letters in Mathematical Physics}, number = {1}, pages = {75 -- 84}, publisher = {Springer}, title = {{General decomposition of radial functions on ℝn and applications to N-body quantum systems}}, doi = {10.1023/A:1020204818938}, volume = {61}, year = {2002}, } @article{2353, abstract = {A commonly used theoretical definition of superfluidity in the ground state of a Bose gas is based on the response of the system to an imposed velocity field or, equivalently, to twisted boundary conditions in a box. We are able to carry out this program in the case of a dilute interacting Bose gas in a trap, and we prove that a gas with repulsive interactions is 100% superfluid in the dilute limit in which the Gross-Pitaevskii equation is exact. This is the first example in an experimentally realistic continuum model in which superfluidity is rigorously verified.}, author = {Lieb, Élliott and Seiringer, Robert and Yngvason, Jakob}, issn = {0163-1829}, journal = {Physical Review B - Condensed Matter and Materials Physics}, number = {13}, publisher = {American Physical Society}, title = {{Superfluidity in dilute trapped Bose gases}}, doi = {10.1103/PhysRevB.66.134529}, volume = {66}, year = {2002}, } @article{2420, abstract = {A corner cut in dimension d is a finite subset of N0d that can be separated from its complement in N0d by an affine hyperplane disjoint from N0d. Corner cuts were first investigated by Onn and Sturmfels [Adv. Appl. Math. 23 (1999) 29-48], their original motivation stemmed from computational commutative algebra. Let us write (Nd0k)cut for the set of corner cuts of cardinality k; in the computational geometer's terminology, these are the k-sets of N0d. Among other things, Onn and Sturmfels give an upper bound of O(k2d(d-1)/(d+1)) for the size of (Nd0k)cut when the dimension is fixed. In two dimensions, it is known (see [Corteel et al., Adv. Appl. Math. 23 (1) (1999) 49-53]) that #(Nd0k)cut = Θ(k log k). We will see that in general, for any fixed dimension d, the order of magnitude of #(Nd0k)cut is between kd-1 log k and (k log k)d-1. (It has been communicated to me that the same bounds have been found independently by G. Rémond.) In fact, the elements of (Nd0k)cut correspond to the vertices of a certain polytope, and what our proof shows is that the above upper bound holds for the total number of flags of that polytope.}, author = {Wagner, Uli}, issn = {0196-8858}, journal = {Advances in Applied Mathematics}, number = {2}, pages = {152 -- 161}, publisher = {ACM}, title = {{On the number of corner cuts}}, doi = {10.1016/S0196-8858(02)00014-3}, volume = {29}, year = {2002}, } @inproceedings{2421, abstract = {Intersection graphs of disks and of line segments, respectively, have been well studied, because of both, practical applications and theoretically interesting properties of these graphs. Despite partial results, the complexity status of the Clique problem for these two graph classes is still open. Here, we consider the Clique problem for intersection graphs of ellipses which in a sense, interpolate between disc and ellipses, and show that it is APX-hard in that case. Moreover, this holds even if for all ellipses, the ratio of the larger over the smaller radius is some prescribed number. To our knowledge, this is the first hardness result for the Clique problem in intersection graphs of objects with finite description complexity. We also describe a simple approximation algorithm for the case of ellipses for which the ratio of radii is bounded.}, author = {Ambühl, Christoph and Wagner, Uli}, booktitle = {Proceedings of the 13th International Symposium on Algorithms and Computation}, isbn = {9783540001423}, location = {Vancouver, Canada}, pages = {489 -- 500}, publisher = {Springer}, title = {{On the Clique problem in intersection graphs of ellipses}}, doi = {10.1007/3-540-36136-7_43}, volume = {2518}, year = {2002}, } @article{2613, abstract = {In this investigation, we report identification and characterization of a 95 kDa postsynaptic density protein (PSD-95)/discs-large/ ZO-1 (PDZ) domain-containing protein termed tamalin, also recently named GRP1-associated scaffold protein (GRASP), that interacts with group 1 metabotropic glutamate receptors (mGluRs). The yeast two-hybrid system and in vitro pull-down assays indicated that the PDZ domain-containing, amino-terminal half of tamalin directly binds to the class I PDZ-binding motif of group 1 mGluRs. The C-terminal half of tamalin also bound to cytohesins, the members of guanine nucleotide exchange factors (GEFs) specific for the ADP-ribosylation factor (ARF) family of small GTP-binding proteins. Tamalin mRNA is expressed predominantly in the telencephalic region and highly overlaps with the expression of group 1 mGluR mRNAs. Both tamalin and cytohesin-2 were enriched and codistributed with mGluR1a in postsynaptic membrane fractions. Importantly, recombinant and native mGluR1a/tamalin/cytohesin-2 complexes were coimmunoprecipitated from transfected COS-7 cells and rat brain tissue, respectively. Transfection of tamalin and mutant tamalin lacking a cytohesin-binding domain caused an increase and decrease in cell-surface expression of mGluR1a in COS-7 cells, respectively. Furthermore, adenovirus-mediated expression of tamalin and dominant-negative tamalin facilitated and reduced the neuritic distribution of endogenous mGluR5 in cultured hippocampal neurons, respectively. The results indicate that tamalin plays a key role in the association of group 1 mGluRs with the ARF-specific GEF proteins and contributes to intracellular trafficking and the macromolecular organization of group 1 mGluRs at synapses.}, author = {Kitano, Jun and Kimura, Kouji and Yamazaki, Yoshimitsu and Soda, Takeshi and Shigemoto, Ryuichi and Nakajima, Yoshiaki and Nakanishi, Shigetada}, issn = {0270-6474}, journal = {Journal of Neuroscience}, number = {4}, pages = {1280 -- 1289}, publisher = {Society for Neuroscience}, title = {{Tamalin, a PDZ domain-containing protein, links a protein complex formation of group 1 metabotropic glutamate receptors and the guanine nucleotide exchange factor cytohesins}}, doi = {10.1523/JNEUROSCI.22-04-01280.2002}, volume = {22}, year = {2002}, }