@article{18418,
  abstract     = {In this correspondence, we consider the problem of multi-input multi output (MIMO) quasi maximum likelihood (QML) blind deconvolution. We examine two classes of estimators, which are commonly believed to be suitable for super and sub-Gaussian sources. We state the consistency conditions and demonstrate a source distribution, for which the studied estimators are unsuitable, in the sense that they are inconsistent.},
  author       = {Bronstein, Alexander and Bronstein, M.M. and Zibulevsky, M.},
  issn         = {1941-0476},
  journal      = {IEEE Transactions on Signal Processing},
  number       = {7},
  pages        = {2576--2579},
  publisher    = {Institute of Electrical and Electronics Engineers (IEEE)},
  title        = {{Quasi maximum likelihood MIMO blind deconvolution: Super- and sub-Gaussianity versus consistency}},
  doi          = {10.1109/tsp.2005.849221},
  volume       = {53},
  year         = {2005},
}

@article{18727,
  abstract     = {Gravitational lensing can amplify the apparent brightness of distant sources. Images that are highly magnified are often part of multiply imaged systems, but we consider the possibility of having large magnifications without additional detectable images. In rare but nonnegligible situations, lensing can produce a single highly magnified image; this phenomenon is mainly associated with massive cluster-scale halos (≳1013.5 M☉). Alternatively, lensing can produce multiply imaged systems in which the extra images are either unresolved or too faint to be detectable. This phenomenon is dominated by galaxies and lower mass halos (≲1012 M☉) and is very sensitive to the inner density profile of the halos. Although we study the general problem, we customize our calculations to four quasars at redshift z ≈ 6 in the Sloan Digital Sky Survey (SDSS), for which Richards et al. (2004) have ruled out the presence of extra images down to an image splitting of Δθ = 0farcs3 and a flux ratio of f = 0.01. We predict that 9%-29% of all z ≈ 6 quasars that are magnified by a factor of μ > 10 would lack detectable extra images, with 5%-10% being true singly imaged systems. The maximum of 29% is reached only in the unlikely event that all low-mass (≲1010 M☉) halos have highly concentrated (isothermal) profiles. In more realistic models in which dwarf halos have flatter (Navarro-Frenk-White) inner profiles, the maximum probability is ~10%. We conclude that the probability that all four SDSS quasars are magnified by a factor of 10 is ≲10-4. The only escape from this conclusion is if there are many (>10) multiply imaged z ≈ 6 quasars in the SDSS database that have not yet been identified, which seems unlikely. In other words, lensing cannot explain the brightnesses of the z ≈ 6 quasars, and models that invoke lensing to avoid having billion-solar-mass black holes in the young universe are not viable.},
  author       = {Keeton, Charles R. and Kuhlen, Michael and Haiman, Zoltán},
  issn         = {1538-4357},
  journal      = {The Astrophysical Journal},
  number       = {2},
  pages        = {559--573},
  publisher    = {American Astronomical Society},
  title        = {{Gravitational lensing magnification without multiple imaging}},
  doi          = {10.1086/427722},
  volume       = {621},
  year         = {2005},
}

@inproceedings{18728,
  abstract     = {We discuss currently available observational constraints on the reionization history of the intergalactic medium (IGM), and the extent to which accreting black holes (BHs) can help explain these observations. We show new evidence, based on the combined statistics of Lyman α and β absorption in quasar spectra, that the IGM contains a significant amount of neutral hydrogen, and is experiencing rapid ionization at redshift z~ 6. However, we argue that quasar BHs, even faint ones that are below the detection thresholds of existing optical surveys, are unlikely to drive the evolution of the neutral fraction around this epoch, because they would over–produce the present–day soft X–ray background. On the other hand, the seeds of the z~ 6 quasar BHs likely appeared at much earlier epochs (z~ 20), and produced hard ionizing radiation by accretion. These early BHs are promising candidates to account for the high redshift (z~ 15) ionization implied by the recent cosmic microwave anisotropy data from WMAP. Using a model for the growth of BHs by accretion and mergers in a hierarchical cosmology, we suggest that the early growth of quasars must include a super-Eddington growth phase, and that, although not yet optically identified, the FIRST radio survey may have already detected several thousand >108M⊙ BHs at z>6.},
  author       = {Haiman, Zoltán and Dijkstra, M. and Mesinger, A.},
  booktitle    = {Proceedings of the MPA/ESO/MPE/USM Joint Astronomy Conference},
  isbn         = {9783540252757},
  issn         = {1611-6143},
  location     = {Garching, Germany},
  pages        = {30--41},
  publisher    = {Springer Nature},
  title        = {{The growth of the earliest supermassive black holes and their contribution to reionization}},
  doi          = {10.1007/11403913_3},
  year         = {2005},
}

@article{18738,
  abstract     = {Gravitational lensing can amplify the apparent brightness of distant sources. Images that are highly magnified are often part of multiply imaged systems, but we consider the possibility of having large magnifications without additional detectable images. In rare but nonnegligible situations, lensing can produce a single highly magnified image; this phenomenon is mainly associated with massive cluster-scale halos (≳1013.5 M☉). Alternatively, lensing can produce multiply imaged systems in which the extra images are either unresolved or too faint to be detectable. This phenomenon is dominated by galaxies and lower mass halos (≲1012 M☉) and is very sensitive to the inner density profile of the halos. Although we study the general problem, we customize our calculations to four quasars at redshift z ≈ 6 in the Sloan Digital Sky Survey (SDSS), for which Richards et al. (2004) have ruled out the presence of extra images down to an image splitting of Δθ = 0farcs3 and a flux ratio of f = 0.01. We predict that 9%-29% of all z ≈ 6 quasars that are magnified by a factor of μ > 10 would lack detectable extra images, with 5%-10% being true singly imaged systems. The maximum of 29% is reached only in the unlikely event that all low-mass (≲1010 M☉) halos have highly concentrated (isothermal) profiles. In more realistic models in which dwarf halos have flatter (Navarro-Frenk-White) inner profiles, the maximum probability is ~10%. We conclude that the probability that all four SDSS quasars are magnified by a factor of 10 is ≲10-4. The only escape from this conclusion is if there are many (>10) multiply imaged z ≈ 6 quasars in the SDSS database that have not yet been identified, which seems unlikely. In other words, lensing cannot explain the brightnesses of the z ≈ 6 quasars, and models that invoke lensing to avoid having billion-solar-mass black holes in the young universe are not viable.},
  author       = {Keeton, Charles R. and Kuhlen, Michael and Haiman, Zoltán},
  issn         = {1538-4357},
  journal      = {The Astrophysical Journal},
  number       = {2},
  pages        = {559--573},
  publisher    = {American Astronomical Society},
  title        = {{Gravitational lensing magnification without multiple imaging}},
  doi          = {10.1086/427722},
  volume       = {621},
  year         = {2005},
}

@article{12657,
  abstract     = {An enhanced temperature-index glacier melt model, incorporating incoming shortwave radiation and albedo, is presented. The model is an attempt to combine the high temporal resolution and accuracy of physically based melt models with the lower data requirements and computational simplicity of empirical melt models, represented by the ‘degree-day’ method and its variants. The model is run with both measured and modelled radiation data, to test its applicability to glaciers with differing data availability. Five automatic weather stations were established on Haut Glacier d’Arolla, Switzerland, between May and September 2001. Reference surface melt rates were calculated using a physically based energy-balance melt model. The performance of the enhanced temperature-index model was tested at each of the four validation stations by comparing predicted hourly melt rates with reference melt rates. Predictions made with three other temperature-index models were evaluated in the same way for comparison. The enhanced temperature-index model offers significant improvements over the other temperature-index models, and accounts for 90–95% of the variation in the reference melt rate. The improvement is lower, but still significant, when the model is forced by modelled shortwave radiation data, thus offering a better alternative to existing models that require only temperature data input.},
  author       = {Pellicciotti, Francesca and Brock, Ben and Strasser, Ulrich and Burlando, Paolo and Funk, Martin and Corripio, Javier},
  issn         = {1727-5652},
  journal      = {Journal of Glaciology},
  number       = {175},
  pages        = {573--587},
  publisher    = {Cambridge University Press},
  title        = {{An enhanced temperature-index glacier melt model including the shortwave radiation balance: Development and testing for Haut Glacier d’Arolla, Switzerland}},
  doi          = {10.3189/172756505781829124},
  volume       = {51},
  year         = {2005},
}

@article{1298,
  abstract     = {Genetically encoded fluorescent probes of neural activity represent new promising tools for systems neuroscience. Here, we present a comparative in vivo analysis of 10 different genetically encoded calcium indicators, as well as the pH-sensitive synapto-pHluorin. We analyzed their fluorescence changes in presynaptic boutons of the Drosophila larval neuromuscular junction. Robust neural activity did not result in any or noteworthy fluorescence changes when Flash-Pericam, Camgaroo-1, and Camgaroo-2 were expressed. However, calculated on the raw data, fractional fluorescence changes up to 18% were reported by synapto-pHluorin, Yellow Cameleon 2.0, 2.3, and 3.3, Inverse-Pericam, GCaMP1.3, GCaMP1.6, and the troponin C-based calcium sensor TN-L15. The response characteristics of all of these indicators differed considerably from each other, with GCaMP1.6 reporting high rates of neural activity with the largest and fastest fluorescence changes. However, GCaMP1.6 suffered from photobleaching, whereas the fluorescence signals of the double-chromophore indicators were in general smaller but more photostable and reproducible, with TN-L15 showing the fastest rise of the signals at lower activity rates. We show for GCaMP1.3 and YC3.3 that an expanded range of neural activity evoked fairly linear fluorescence changes and a corresponding linear increase in the signal-to-noise ratio (SNR). The expression level of the indicator biased the signal kinetics and SNR, whereas the signal amplitude was independent. The presented data will be useful for in vivo experiments with respect to the selection of an appropriate indicator, as well as for the correct interpretation of the optical signals.},
  author       = {Reiff, Dierk F and Ihring, Alexandra and Guerrero, Giovanna and Isacoff, Ehud Y and Maximilian Jösch and Nakai, Junichi and Borst, Alexander},
  journal      = {Journal of Neuroscience},
  number       = {19},
  pages        = {4766 -- 4778},
  publisher    = {Society for Neuroscience},
  title        = {{In vivo performance of genetically encoded indicators of neural activity in flies}},
  doi          = {10.1523/JNEUROSCI.4900-04.2005},
  volume       = {25},
  year         = {2005},
}

@article{1962,
  abstract     = {

Complex I of respiratory chains plays a central role in bioenergetics and is implicated in many human neurodegenerative diseases. An understanding of its mechanism requires a knowledge of the organization of redox centers. The arrangement of iron-sulfur clusters in the hydrophilic domain of complex I from Thermus thermophilus has been determined with the use of x-ray crystallography. One binuclear and six tetranuclear clusters are arranged, maximally 14 angstroms apart, in an 84-angstrom-long electron transfer chain. The binuclear cluster N1a and the tetranuclear cluster N7 are not in this pathway. Cluster N1a may play a role in the prevention of oxidative damage. The structure provides a framework for the interpretation of the large amounts of data accumulated on complex I.},
  author       = {Hinchliffe, Philip  and Leonid Sazanov},
  journal      = {Science},
  number       = {5735},
  pages        = {771 -- 774},
  publisher    = {American Association for the Advancement of Science},
  title        = {{Biochemistry: Organization of iron-sulfur clusters in respiratory complex I}},
  doi          = {10.1126/science.1113988},
  volume       = {309},
  year         = {2005},
}

@article{11120,
  abstract     = {The nuclear envelope (NE) is a highly specialized membrane that delineates the eukaryotic cell nucleus. It is composed of the inner and outer nuclear membranes, nuclear pore complexes (NPCs) and, in metazoa, the lamina. The NE not only regulates the trafficking of macromolecules between nucleoplasm and cytosol but also provides anchoring sites for chromatin and the cytoskeleton. Through these interactions, the NE helps position the nucleus within the cell and chromosomes within the nucleus, thereby regulating the expression of certain genes. The NE is not static, rather it is continuously remodeled during cell division. The most dramatic example of NE reorganization occurs during mitosis in metazoa when the NE undergoes a complete cycle of disassembly and reformation. Despite the importance of the NE for eukaryotic cell life, relatively little is known about its biogenesis or many of its functions. We thus are far from understanding the molecular etiology of a diverse group of NE-associated diseases.},
  author       = {HETZER, Martin W and Walther, Tobias C. and Mattaj, Iain W.},
  issn         = {1530-8995},
  journal      = {Annual Review of Cell and Developmental Biology},
  keywords     = {Cell Biology, Developmental Biology},
  pages        = {347--380},
  publisher    = {Annual Reviews},
  title        = {{Pushing the envelope: Structure, function, and dynamics of the nuclear periphery}},
  doi          = {10.1146/annurev.cellbio.21.090704.151152},
  volume       = {21},
  year         = {2005},
}

@book{210,
  abstract     = {Harold Davenport was one of the truly great mathematicians of the twentieth century. Based on lectures he gave at the University of Michigan in the early 1960s, this book is concerned with the use of analytic methods in the study of integer solutions to Diophantine equations and Diophantine inequalities. It provides an excellent introduction to a timeless area of number theory that is still as widely researched today as it was when the book originally appeared. The three main themes of the book are Waring's problem and the representation of integers by diagonal forms, the solubility in integers of systems of forms in many variables, and the solubility in integers of diagonal inequalities. For the second edition of the book a comprehensive foreword has been added in which three prominent authorities describe the modern context and recent developments. A thorough bibliography has also been added.},
  author       = {Davenport, Harold and Browning, Timothy D},
  pages        = {140},
  publisher    = {Cambridge University Press},
  title        = {{Analytic Methods for Diophantine Equations and Diophantine Inequalities}},
  doi          = {10.1017/CBO9780511542893},
  year         = {2005},
}

@article{211,
  abstract     = {Let f ∈ ℤ[x] be a polynomial of degree d. The paucity of non-trivial positive integer solutions to the equation f(x1)+f(x 2)=f(x3)+f(x4) is established, provided that d ≤ 7$. Also the corresponding situation is investigated for equal sums of three like polynomials.},
  author       = {Timothy Browning},
  journal      = {Bulletin of the London Mathematical Society},
  number       = {6},
  pages        = {801 -- 808},
  publisher    = {John Wiley and Sons Ltd},
  title        = {{Equal sums of like polynomials}},
  doi          = {10.1112/S0024609305004741},
  volume       = {37},
  year         = {2005},
}

@article{212,
  abstract     = {For any n ≧ 2, let F ∈ ℤ [ x 1, … , xn ] be a form of degree d≧ 2, which produces a geometrically irreducible hypersurface in ℙn–1. This paper is concerned with the number N(F;B) of rational points on F = 0 which have height at most B. For any ε > 0 we establish the estimate N(F; B) = O(B n− 2+ ε ), whenever either n ≦ 5 or the hypersurface is not a union of lines. Here the implied constant depends at most upon d, n and ε.},
  author       = {Timothy Browning and Heath-Brown, Roger},
  journal      = {Journal fur die Reine und Angewandte Mathematik},
  number       = {584},
  pages        = {83 -- 115},
  publisher    = {Walter de Gruyter and Co },
  title        = {{Counting rational points on hypersurfaces}},
  doi          = {https://doi.org/10.1515/crll.2005.2005.584.83},
  year         = {2005},
}

@article{214,
  abstract     = {Given an absolutely irreducible ternary form F, the purpose of this paper is to produce better upper bounds for the number of integer solutions to the equation F=0, that are restricted to lie in very lopsided boxes. As an application of the main result, a new paucity estimate is obtained for equal sums of two like powers.},
  author       = {Timothy Browning and Heath-Brown, Roger},
  journal      = {Mathematische Zeitschrift},
  number       = {2},
  pages        = {233 -- 247},
  publisher    = {Unknown},
  title        = {{Plane curves in boxes and equal sums of two powers}},
  doi          = {10.1007/s00209-004-0719-z},
  volume       = {251},
  year         = {2005},
}

@article{217,
  abstract     = {We show that the number of nontrivial rational points of height at most B, which lie on the cubic surface x1 x2 x3 = x4 (x1 + x2 + x3)2, has order of magnitude B (log B)6. This agrees with Manin's conjecture.},
  author       = {Timothy Browning},
  journal      = {Journal of Number Theory},
  number       = {2},
  pages        = {242 -- 283},
  publisher    = {Elsevier},
  title        = {{The density of rational points on a certain singular cubic surface}},
  doi          = {10.1016/j.jnt.2005.11.007},
  volume       = {119},
  year         = {2005},
}

@article{2307,
  abstract     = {The human norepinephrine (NE) transporter (hNET) attenuates neuronal signaling by rapid NE clearance from the synaptic cleft, and NET is a target for cocaine and amphetamines as well as therapeutics for depression, obsessive-compulsive disorder, and post-traumatic stress disorder. In spite of its central importance in the nervous system, little is known about how NET substrates, such as NE, 1-methyl-4-tetrahydropyridinium (MPP+), or amphetamine, interact with NET at the molecular level. Nor do we understand the mechanisms behind the transport rate. Previously we introduced a fluorescent substrate similar to MPP+, which allowed separate and simultaneous binding and transport measurement (Schwartz, J. W., Blakely, R. D., and DeFelice, L. J. (2003) J. Biol. Chem. 278, 9768-9777). Here we use this substrate, 4-(4-(dimethylamino)styrl)-N-methyl-pyridinium (ASP+), in combination with green fluorescent protein-tagged hNETs to measure substrate-transporter stoichiometry and substrate binding kinetics. Calibrated confocal microscopy and fluorescence correlation spectroscopy reveal that hNETs, which are homo-multimers, bind one substrate molecule per transporter subunit. Substrate residence at the transporter, obtained from rapid on-off kinetics revealed in fluorescence correlation spectroscopy, is 526 μs. Substrate residence obtained by infinite dilution is 1000 times slower. This novel examination of substrate-transporter kinetics indicates that a single ASP + molecule binds and unbinds thousands of times before being transported or ultimately dissociated from hNET. Calibrated fluorescent images combined with mass spectroscopy give a transport rate of 0.06 ASP +/hNET-protein/s, thus 36,000 on-off binding events (and 36 actual departures) occur for one transport event. Therefore binding has a low probability of resulting in transport. We interpret these data to mean that inefficient binding could contribute to slow transport rates.},
  author       = {Schwartz, Joel W and Gaia Novarino and Piston, David W and DeFelice, Louis J},
  journal      = {Journal of Biological Chemistry},
  number       = {19},
  pages        = {19177 -- 19184},
  publisher    = {American Society for Biochemistry and Molecular Biology},
  title        = {{Substrate binding stoichiometry and kinetics of the norepinephrine transporter}},
  doi          = {10.1074/jbc.M412923200},
  volume       = {280},
  year         = {2005},
}

@book{2335,
  abstract     = {This book contains a unique survey of the mathematically rigorous results about the quantum-mechanical many-body problem that have been obtained by the authors in the past seven years. It addresses a topic that is not only rich mathematically, using a large variety of techniques in mathematical analysis, but is also one with strong ties to current experiments on ultra-cold Bose gases and Bose-Einstein condensation. The book provides a pedagogical entry into an active area of ongoing research for both graduate students and researchers. It is an outgrowth of a course given by the authors for graduate students and post-doctoral researchers at the Oberwolfach Research Institute in 2004. The book also provides a coherent summary of the field and a reference for mathematicians and physicists active in research on quantum mechanics.},
  author       = {Lieb, Élliott and Seiringer, Robert and Solovej, Jan and Yngvason, Jakob},
  isbn         = {978-3-7643-7336-8},
  pages        = {VIII, 203},
  publisher    = {Birkhäuser Verlag},
  title        = {{The Mathematics of the Bose gas and its Condensation}},
  doi          = {10.1007/b137508},
  volume       = {34},
  year         = {2005},
}

@inbook{2336,
  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, and to explore new regimes not treated before. 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 2πħ2 aρ/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 N 7/5 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 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, several 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 and superfluidity as we have shown. On the frontier of experimental developments is the possibility that a dilute gas in an elongated trap will behave like a one-dimensional system; we have proved this mathematically. 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; using this we can also prove the N 7/5 formula for the ground state energy of the two-component charged Bose gas proposed by Dyson in 1967. All of this is quite recent work and it is hoped that the mathematical methodology might be useful, ultimately, to solve more complex problems connected with these interesting systems.},
  author       = {Lieb, Élliott H and Robert Seiringer and Solovej, Jan P and Yngvason, Jakob},
  booktitle    = {Perspectives in Analysis},
  editor       = {Benedicks, Michael and Jones, Peter W and Smirnov, Stanislav and Winckler, Björn},
  pages        = {97 -- 183},
  publisher    = {Springer},
  title        = {{The quantum-mechanical many-body problem: The Bose gas}},
  doi          = {10.1007/3-540-30434-7_9},
  volume       = {27},
  year         = {2005},
}

@article{2359,
  abstract     = {The validity of substituting a c-number z for the k = 0 mode operator a0 is established rigorously in full generality, thereby verifying one aspect of Bogoliubov's 1947 theory. This substitution not only yields the correct value of thermodynamic quantities such as the pressure or ground state energy, but also the value of |z|2 that maximizes the partition function equals the true amount of condensation in the presence of a gauge-symmetry-breaking term. This point had previously been elusive.},
  author       = {Lieb, Élliott H and Robert Seiringer and Yngvason, Jakob},
  journal      = {Physical Review Letters},
  number       = {8},
  publisher    = {American Physical Society},
  title        = {{Justification of c-number substitutions in bosonic hamiltonians}},
  doi          = {10.1103/PhysRevLett.94.080401},
  volume       = {94},
  year         = {2005},
}

@article{2361,
  abstract     = {The strong subadditivity of entropy plays a key role in several areas of physics and mathematics. It states that the entropy S[±]=- Tr(ϱlnϱ) of a density matrix ϱ123 on the product of three Hilbert spaces satisfies S[ϱ123]- S[ϱ12]≤S[ϱ23]-S[ϱ2]. We strengthen this to S[ϱ123]-S[ϱ12] ≤αnα(S[ϱ23α]-S[ϱ2α]), where the nα are weights and the ϱ23α are partitions of ϱ23. Correspondingly, there is a strengthening of the theorem that the map A|Trexp[L+lnA] is concave. As applications we prove some monotonicity and convexity properties of the Wehrl coherent state entropy and entropy inequalities for quantum gases.},
  author       = {Lieb, Élliott H and Robert Seiringer},
  journal      = {Physical Review A - Atomic, Molecular, and Optical Physics},
  number       = {6},
  publisher    = {American Physical Society},
  title        = {{Stronger subadditivity of entropy}},
  doi          = {10.1103/PhysRevA.71.062329},
  volume       = {71},
  year         = {2005},
}

@article{2362,
  abstract     = {Recent developments in the physics of low-density trapped gases make it worthwhile to verify old, well-known results that, while plausible, were based on perturbation theory and assumptions about pseudopotentials. We use and extend recently developed techniques to give a rigorous derivation of the asymptotic formula for the ground-state energy of a dilute gas of N fermions interacting with a short-range, positive potential of scattering length a. For spin-12 fermions, this is E∼E0+(22m)2πNa, where E0 is the energy of the noninteracting system and is the density. A similar formula holds in two dimensions (2D), with a replaced by ln(a2). Obviously this 2D energy is not the expectation value of a density-independent pseudopotential.},
  author       = {Lieb, Élliott H and Robert Seiringer and Solovej, Jan P},
  journal      = {Physical Review A - Atomic, Molecular, and Optical Physics},
  number       = {5},
  publisher    = {American Physical Society},
  title        = {{Ground state energy of the low density Fermi gas}},
  doi          = {10.1103/PhysRevA.71.053605},
  volume       = {71},
  year         = {2005},
}

@article{2427,
  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 disks and line segments, and show that the problem 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. Furthermore, the reduction immediately carries over to intersection graphs of triangles. To our knowledge, this is the first hardness result for the Clique problem in intersection graphs of convex 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 Uli Wagner},
  journal      = {Theory of Computing Systems},
  number       = {3},
  pages        = {279 -- 292},
  publisher    = {Springer},
  title        = {{The Clique problem in intersection graphs of ellipses and triangles}},
  doi          = {10.1007/s00224-005-1141-6},
  volume       = {38},
  year         = {2005},
}