@inproceedings{11926, abstract = {We present the first polylog-competitive online algorithm for the general multicast problem in the throughput model. The ratio of the number of requests accepted by the optimum offline alaorithm to the exoected number of reauests accepted by our algorithm is O(jlog n + log log M)(log n + log M) log n), where M is the number of multicast groups and n is the number of nodes in the nraoh. We show that this is close to optimum by presenting-an*R(log nlog M) lower bound on this ratio for anv randomized online algorithm against an oblivious adversary, when M is much lar&r than the link capacities. Our lower bound applies even in the restricted case where the link capacities are much larger than bandwidth requested by a single multicast. We also present a simple proof showing that it is impossible to be competitive against an adaptive online adversary. As in the previous online routing algorithms, our algorithm uses edge-costs when deciding on which is the best path to use. In contrast to the nrevious comnetitive aleorithms in the throughput modei, our cost is-not a direct function of the edne load. The new cost definition allows us to decouple the effects of routing and admission decisions of different multicast groups. }, author = {Goel, Ashish and Henzinger, Monika H and Plotkin, Serge}, booktitle = {9th Annual ACM SIAM Symposium on Discrete Algorithms}, isbn = {0898714109}, location = {San Francisco, CA, United States}, pages = {97--106}, publisher = {Society for Industrial and Applied Mathematics}, title = {{An online throughput-competitive algorithm for multicast routing and admission control}}, year = {1998}, } @article{2583, abstract = {Substance P receptor (SPR)-immunoreactive neurons projecting to the periaqueductal gray (PAG) were examined in the rat spinal trigeminal nucleus and spinal cord by a retrograde tracing method combined with immunofluorescence histochemistry. After injection of Fluoro-gold (FG) into the PAG, SPR-immunoreactive neurons labeled with FG were observed mainly in the lateral spinal nucleus and lamina I of the medullary and spinal dorsal horns and additionally in laminae V and X of the spinal cord.}, author = {Li, Jin and Ding, Yu and Xiong, Kang and Li, Ji and Shigemoto, Ryuichi and Mizuno, Noboru}, issn = {0168-0102}, journal = {Neuroscience Research}, number = {3}, pages = {219 -- 225}, publisher = {Elsevier}, title = {{Substance P receptor (NK1)-immunoreactive neurons projecting to the periaqueductal gray: Distribution in the spinal trigeminal nucleus and the spinal cord of the rat}}, doi = {10.1016/S0168-0102(97)00132-6}, volume = {30}, year = {1998}, } @article{2584, abstract = {The distributions of two alternative splicing variants of metabotropic glutamate receptor mGluR7, mGluR7a and mGluR7b, were examined immunohistochemically in the rat and mouse by using variant-specific antibodies raised against C-terminal portions of rat mGluR7a and human mGluR7b. Many regions throughout the central nervous system (CNS) showed mGluR7-like immunoreactivities (LI). The distribution patterns of mGluR7-LI in the rat were substantially the same as those in the mouse, although some species differences were observed in a few regions. Intense mGluR7a-LI was seen in the main and accessory olfactory bulbs, anterior olfactory nucleus, islands of Calleja, superficial layers of the olfactory tubercle, piriform cortex and entorhinal cortex, periamygdaloid cortex, amygdalohippocampal area, hippocampus, layer I of the neocortical regions, globus pallidus, superficial layers of the superior colliculus, locus coeruleus, and superficial layers of the medullary and spinal dorsal horns. The distribution of mGluR7b was more restricted. It was intense in the islands of Calleja, substantia innominata, hippocampus, ventral pallidum, and globus pallidus. The medial habenular nucleus also showed intense mGluR7a-LI in the rat but not in the mouse. For both mGluR7a- and mGluR7b-LI, localization in the active zones of presynaptic axon terminals was confirmed electron microscopically at synapses of both the asymmetrical and symmetrical types. It is noteworthy that mGluR7a-LI is seen preferentially in relay nuclei of the sensory pathways and that both mGluR7a- and mGluR7b-LI are observed not only in presumed glutamatergic axon terminals, but also in non-glutamatergic axon terminals including presumed inhibitory ones. Thus, mGluR7 may play roles not only as an autoreceptor in glutamatergic axon terminals, but also as a presynaptic heteroreceptor in non-glutamatergic axon terminals in various CNS regions.}, author = {Kinoshita, Ayae and Shigemoto, Ryuichi and Ohishi, Hitoshi and Van Der Putten, Herman and Mizuno, Noboru}, issn = {0021-9967}, journal = {Journal of Comparative Neurology}, number = {3}, pages = {332 -- 352}, publisher = {Wiley-Blackwell}, title = {{Immunohistochemical localization of metabotropic glutamate receptors, mGluR7a and mGluR7b, in the central nervous system of the adult rat and mouse: A light and electron microscopic study}}, doi = {10.1002/(SICI)1096-9861(19980413)393:3<332::AID-CNE6>3.0.CO;2-2}, volume = {393}, year = {1998}, } @article{2585, abstract = {Localization of metabetropic glutamate receptor subtypes, mGluR1, mGluRlu, mGluR2/3, mGluR4a, mGluR5, mGluR7a, mGluR7b, and mGluR8, was examined in some of the target areas of projection fibers from the main and accessory olfactory bulbs (MOB and AOB) by using subtype-specific antibodies. The superficial layer of the olfactory tubercle and layer Ia of the pitiform cortex, the target areas of MOB, showed marked mGluR1-, mGluR5-, mGluR7a-, and mGluR8-like immunoreactivities (-LI), and rather weak mGluR2/3-LI. The periamygdaloid cortical region including the target areas of both MOB and AOB showed intense mGluR2/3-LI as well as marked mGluRl-, mGluR5-, mGluR7a-, and mGluRS-LI. No significant mGluR1a-, mGluR4a-, or mGluR7b-LI was seen in these regions. After transection of the lateral olfactory tract, mGluR2/3-, mGluR7a-, and mGluR8-LI were reduced markedly in the target regions on the side ipsilateral to the transection; no significant changes were detected in mGluR1- or mGIuR5-LI. Double labeling experiments indicated light and electron microscopically colocalization of mGluR7a- and mGluRS-LI in axon terminals on dendritic shafts of presumed interneurons in the superficial layer of the olfactory tubercle and layer Ia of the piriform cortex. Electron microscopically mGluR2/3-LI was seen in preterminal and terminal portions of axons, whereas mGluR7a- and mGluRS-LI were associated with presynaptic membrane specialization. Immunolabeled axon terminals were filled with round synaptic vesicles and constituted asymmetric synapses with dendritic profiles. The results suggest that glutamate release from axon terminals of projection fibers from MOB and AOB is regulated presynaptically and differentially through mGluR2/3, mGluR7a, and/or mGluRS.}, author = {Wada, Eiki and Shigemoto, Ryuichi and Kinoshita, Ayae and Ohishi, Hitoshi and Mizuno, Noboru}, issn = {0021-9967}, journal = {Journal of Comparative Neurology}, number = {4}, pages = {493 -- 504}, publisher = {Wiley-Blackwell}, title = {{Metabotropic glutamate receptor subtypes in axon terminals of projection fibers from the main and accessory olfactory bulbs: A light and electron microscopic immunohistochemical study in the rat}}, doi = {10.1002/(SICI)1096-9861(19980420)393:4<493::AID-CNE8>3.0.CO;2-W}, volume = {393}, year = {1998}, } @article{2586, abstract = {The role of inhibitory Golgi cells in cerebellar function was investigated by selectively ablating Golgi cells expressing human interleukin-2 receptor α subunit in transgenic mice, using the immunotoxin- mediated cell targeting technique. Golgi cell disruption caused severe acute motor disorders. These mice showed gradual recovery but retained a continuing inability to perform compound movements. Optical and electrical recordings combined with immunocytological analysis indicated that elimination of Golgi cells not only reduces GABA-mediated inhibition but also attenuates functional NMDA receptors in granule cells. These results demonstrate that synaptic integration involving both GABA inhibition and NMDA receptor activation is essential for compound motor coordination. Furthermore, this integration can adapt after Golgi cell elimination so as not to evoke overexcitation by the reduction of NMDA receptors.}, author = {Watanabe, Dai and Inokawa, Hitoshi and Hashimoto, Kouichi and Suzuki, Noboru and Kano, Masanobu and Shigemoto, Ryuichi and Hirano, Tomoo and Toyama, Keisuke and Kaneko, Satoshi and Yokoi, Mineto and Moriyoshi, Koki and Suzuki, Misao and Kobayashi, Kazuto and Nagatsu, Toshiharu and Kreitman, Robert and Pastan, Ira and Nakanishi, Shigetada}, issn = {0092-8674}, journal = {Cell}, number = {1}, pages = {17 -- 27}, publisher = {Cell Press}, title = {{Ablation of cerebellar Golgi cells disrupts synaptic integration involving GABA inhibition and NMDA receptor activation in motor coordination}}, doi = {10.1016/S0092-8674(00)81779-1}, volume = {95}, year = {1998}, } @article{2588, abstract = {B-type receptors for the neurotransmitter GABA (γ-aminobutyric acid) inhibit neuronal activity through G-protein-coupled second-messenger systems, which regulate the release of neurotransmitters and the activity of ion channels and adenylyl cyclase. Physiological and biochemical studies show that there are differences in drug efficiencies at different GABA(B) receptors, so it is expected that GABA(B)-receptor (GABA(B)R) subtypes exist. Two GABA(B)-receptor splice variants have been cloned (GABA(B)R1a and GABA(B)R1b), but native GABA(B) receptors and recombinant receptors showed unexplained differences in agonist-binding potencies. Moreover, the activation of presumed effector ion channels in heterologous cells expressing the recombinant receptors proved difficult. Here we describe a new GABA(B) receptor subtype, GABA(B)R2, which does not bind available GABA(B) antagonists with measurable potency. GABA(B)R1a, GABA(B)R1b and GABA(B)R2 alone do not activate Kir3-type potassium channels efficiently, but co- expression of these receptors yields a robust coupling to activation of Kir3 channels. We provide evidence for the assembly of heteromeric GABA(B) receptors in vivo and show that GABA(B)R2 and GABA(B)R1a/b proteins immunoprecipitate and localize together at dendritic spines. The heteromeric receptor complexes exhibit a significant increase in agonist- and partial- agonist-binding potencies as compared with individual receptors and probably represent the predominant native GABA(B) receptor. Heteromeric assembly among G-protein-coupled receptors has not, to our knowledge, been described before. }, author = {Kaupmann, Klemens and Malitschek, Barbara and Schuler, Valérie and Heid, Jacob and Froestl, Wolfgang and Beck, Pascal and Mosbacher, Johannes and Bischoff, Serge and Kulik, Ákos and Shigemoto, Ryuichi and Karschin, Andreas and Bettler, Bernhard}, issn = {0028-0836}, journal = {Nature}, number = {6712}, pages = {683 -- 687}, publisher = {Nature Publishing Group}, title = {{ GABA(B)-receptor subtypes assemble into functional heteromeric complexes}}, doi = {10.1038/25360}, volume = {396}, year = {1998}, } @article{2589, abstract = {Immunoreactivity for the substance P receptor (NK1 receptor) has been investigated by light and electron microscopy in the dorsal vagal complexes of adult rats and cats. The general pattern of NK1 immunoreactivity was similar for both rat and cat. Numerous NK1-immunoreactive neurons were present in the area postrema, the nucleus of the solitary tract, and the dorsal motor nucleus of the vagus nerve. The density of labelled neurons differed between the subnuclei of the nucleus of the solitary tract. Overall, the efferent neurons of the dorsal motor nucleus of the vagus nerve highly expressed NK1 when compared to neurons in the nucleus of the solitary tract. The results are discussed with reference to the viscerotopic organisation of the dorsal vagal complex. Ultrastructural analysis demonstrated that NK1 immunoreactivity was present only at the membrane surface of somatic and dendritic profiles of neurons. No labelling was found in axon terminals, axons, or glial processes. NK1 immunoreactivity, as revealed by a preembedding immunogold technique in serial ultrathin sections; was preferentially located at nonsynaptic sites. A semiquantitative study suggested that the density of NK1 receptors is statistically higher at membrane sites free of any contact (synaptic or not) with axon terminals. The subcellular localisation of NK1 immunoreactivity was similar for neurons of both rat and cat. These results suggest that in the dorsal vagal complex, substance P might act on NK1 receptors through a process of volume transmission.}, author = {Baude, Agnès and Shigemoto, Ryuichi}, issn = {0021-9967}, journal = {Journal of Comparative Neurology}, number = {2}, pages = {181 -- 196}, publisher = {Wiley-Blackwell}, title = {{Cellular and subcellular distribution of substance P receptor immunoreactivity in the dorsal vagal complex of the rat and cat: A light and electron microscope study}}, doi = {10.1002/(SICI)1096-9861(19981214)402:2<181::AID-CNE4>3.0.CO;2-B}, volume = {402}, year = {1998}, } @article{2590, abstract = {Unipolar brush cells (UBCs) are a class of small neurons that are densely concentrated in the granular layers of the vestibulocerebellar cortex and dorsal cochlear nucleus. The UBCs form giant synapses with individual mossy fibre rosettes on the dendrioles which make up their brush formations and are provided with numerous, unusual non-synaptic appendages. In accord with the glutamatergic nature of mossy fibres, our previous post-embedding immunocytochemical studies indicated that various ionotropic glutamate receptor subunits are localized at the post-synaptic densities of the giant synapses, whereas the non-synaptic appendages are immunonegative. On the contrary, the metabotropic glutamate receptors mGluR1α and mGluR2/3 are situated at the non-synaptic appendages and are lacking at the post-synaptic densities. Other authors, however, have shown that antibodies to these metabotropic receptors stain both appendages and post-synaptic densities. In the present study, we have re-evaluated the distribution of metabotropic glutamate receptors in the UBCs of the cerebellum and the cochlear nuclear complex by light and electron microscopic pre-embedding immunocytochemistry with subtype-specific antibodies. We confirm that UBCs dendritic brushes are densely immunostained by antibody to mGluR1α particularly in the cerebellum and that antibody to mGluR2/3 labels at least a percentage of the UBC brushes in both the cerebellum and cochlear nuclei. At the ultrastructural level, it appears that mGluR1α and mGluR2/3 immunoreactivities are not associated with the post-synaptic densities of the giant mossy fibre-UBC synapses, but instead are concentrated on the non-synaptic appendages of the cerebellar UBCs. The non-synaptic appendages, therefore, may be an important avenue for regulating the excitability of UBCs and mediating glutamate effects on their still unknown intracellular signal transduction cascades. We also show that the pre-synaptic densities of UBC dendrodendritic junctions are mGluR2/3 positive. As previously demonstrated, antibodies to mGluR1α and mGluR2/3 label subsets of Golgi cells. Antibody to mGluR5 does not stain UBCs in the cerebellum and cochlear nucleus and reveals the somatodendritic compartment of Golgi cells situated in the core of the cerebellar granular layer, whilst cochlear nucleus Golgi cells are mGluR5 negative.}, author = {Jaarsma, Dick and Diño, Maria and Ohishi, Hitoshi and Shigemoto, Ryuichi and Mugnaini, Enrico}, issn = {0300-4864}, journal = {Journal of Neurocytology}, number = {5}, pages = {303 -- 327}, publisher = {Kluwer}, title = {{ Metabotropic glutamate receptors are associated with non-synaptic appendages of unipolar brush cells in rat cerebellar cortex and cochlear nuclear complex}}, doi = {10.1023/A:1006982023657}, volume = {27}, year = {1998}, } @inbook{2695, abstract = {We study a quantum particle in a random potential in two scaling limits: the low density limit (or Boltzman-Grad) and the weak coupling limit. The low density limit is the quantum analogue of the Lorentz gas. In both cases, the phase space density of the quantum evolution defined through the Wigner transform or the Husimi function converges weakly to a linear Boltz-mann equation with collision kernel given by the quantum scattering cross section. }, author = {Erdös, László and Yau, Horng}, booktitle = {Advances in Differential Equations and Mathematical Physics}, issn = {0271-4132}, pages = {137 -- 155}, publisher = {American Mathematical Society}, title = {{Linear Boltzmann equation as scaling limit of quantum Lorentz gas}}, doi = {10.1090/conm/217}, volume = {217}, year = {1998}, } @article{2728, abstract = {We obtain the Lifschitz tail, i.e. the exact low energy asymptotics of the integrated density of states (IDS) of the two-dimensional magnetic Schrödinger operator with a uniform magnetic field and random Poissonian impurities. The single site potential is repulsive and it has a finite but nonzero range. We show that the IDS is a continuous function of the energy at the bottom of the spectrum. This result complements the earlier (nonrigorous) calculations by Brézin, Gross and Itzykson which predict that the IDS is discontinuous at the bottom of the spectrum for zero range (Dirac delta) impurities at low density. We also elucidate the reason behind this apparent controversy. Our methods involve magnetic localization techniques (both in space and energy) in addition to a modified version of the "enlargement of obstacles" method developed by A.-S. Sznitman.}, author = {Erdös, László}, issn = {0044-3719}, journal = {Probability Theory and Related Fields}, number = {3}, pages = {321 -- 371}, publisher = {Springer}, title = {{Lifschitz tail in a magnetic field: The nonclassical regime}}, doi = {10.1007/s004400050193}, volume = {112}, year = {1998}, } @article{3487, abstract = {It is widely accepted that individual neurons in the central nervous system release only a single fast transmitter. The possibility of corelease of fast neurotransmitters was examined by making paired recordings from synaptically connected neurons in spinal cord slices. Unitary inhibitory postsynaptic currents generated at interneuron-motoneuron synapses consisted of a strychnine-sensitive, glycine receptor-mediated component and a bicuculline-sensitive, γ-aminobutyric acid (GABA)(A) receptor-mediated component. These results indicate that spinal interneurons release both glycine and GABA to activate functionally distinct receptors in their postsynaptic target cells. A subset of miniature synaptic currents also showed both components, consistent with corelease from individual synaptic vesicles.}, author = {Jonas, Peter M and Bischofberger, Joseph and Sandkühler, Jürgen}, issn = {0036-8075}, journal = {Science}, number = {5375}, pages = {419 -- 424}, publisher = {American Association for the Advancement of Science}, title = {{Corelease of two fast neurotransmitters at a central synapse}}, doi = {10.1126/science.281.5375.419}, volume = {281}, year = {1998}, } @article{3488, abstract = {We have examined gating and pharmacological characteristics of somatic K+ channels in fast-spiking interneurons and regularly spiking principal neurons of hippocampal slices. In nucleated patches isolated from basket cells of the dentate gyrus, a fast delayed rectifier K+ current component that was highly sensitive to tetraethylammonium (TEA) and 4-aminopyridine (4- AP) (half-maximal inhibitory concentrations <0.1 mM) predominated, contributing an average of 58% to the total K+ current in these cells. By contrast, in pyramidal neurons of the CA1 region a rapidly inactivating A- type K+ current component that was TEA-resistant prevailed, contributing 61% to the total K+ current. Both types of neurons also showed small amounts of the K+ current component mainly found in the other type of neuron and, in addition, a slow delayed rectifier K+ current component with intermediate properties (sow inactivation, intermediate sensitivity to TEA). Single-cell RT-PCR analysis of mRNA revealed that Kv3 (Kv3.1, Kv3.2) subunit transcripts were expressed in almost all (89%) of the interneurons but only in 17% of the pyramidal neurons. In contrast, Kv4 (Kv4.2, Kv4.3) subunit mRNAs were present in 87% of pyramidal neurons but only in 55% of interneurons. Selective block of fast delayed rectifier K+ channels, presumably assembled from Kv3 subunits, by 4-AP reduced substantially the action potential frequency in interneurons. These results indicate that the differential expression of Kv3 and Kv4 subunits shapes the action potential phenotypes of principal neurons and interneurons in the cortex.}, author = {Martina, Marco and Schultz, Jobst and Ehmke, Heimo and Monyer, Hannah and Jonas, Peter M}, issn = {0270-6474}, journal = {Journal of Neuroscience}, number = {20}, pages = {8111 -- 8125}, publisher = {Society for Neuroscience}, title = {{Functional and molecular differences between voltage-gated K+ channels of fast-spiking interneurons and pyramidal neurons of rat hippocampus}}, doi = {10.1523/JNEUROSCI.18-20-08111.1998}, volume = {18}, year = {1998}, } @misc{3506, abstract = {A method of geometric morphing between a first object having a first shape and a second object having a second shape. The method includes the steps of generating a first Delaunay complex corresponding to the first shape and a second Delaunay complex corresponding to the second shape and generating a plurality of intermediary Delaunay complexes defined by a continuous family of mixed shapes corresponding to a mixing of the first shape and the second shape. The method further includes the steps of constructing a first skin corresponding to the first Delaunay complex and a second skin corresponding to the second Delaunay complex and constructing a plurality of intermediary skins corresponding to the plurality of intermediary Delaunay complexes. The first skin, second skin and plurality of intermediary skins may be visually displayed on an output device.}, author = {Edelsbrunner, Herbert and Fu, Ping}, title = {{Apparatus and method for geometric morphing}}, year = {1998}, } @article{3521, abstract = {Spike transmission probability between pyramidal cells and interneurons in the CA1 pyramidal layer was investigated in the behaving rat by the simultaneous recording of neuronal ensembles. Population synchrony was strongest during sharp wave (SPW) bursts. However, the increase was three times larger for pyramidal cells than for interneurons. The contribution of single pyramidal cells to the discharge of interneurons was often large (up to 0.6 probability), as assessed by the presence of significant (<3 ms) peaks in the cross-correlogram. Complex-spike bursts were more effective than single spikes. Single cell contribution was higher between SPW bursts than during SPWs or theta activity. Hence, single pyramidal cells can reliably discharge interneurons, and the probability of spike transmission is behavior dependent.}, author = {Csicsvari, Jozsef L and Hirase, Hajima and Czurkó, András and Buzsáki, György}, issn = {0896-6273}, journal = {Neuron}, number = {1}, pages = {179 -- 189}, publisher = {Elsevier}, title = {{Reliability and state dependence of pyramidal cell-interneuron synapses in the hippocampus: an ensemble approach in the behaving rat}}, doi = {10.1016/S0896-6273(00)80525-5}, volume = {21}, year = {1998}, } @article{3525, author = {Nádasdy, Zoltán and Jozsef Csicsvari and Hirase, Hajima and Czurkó, András and Buzsáki, György}, journal = {European Journal of Neuroscience}, number = {Suppl. 10}, pages = {9409 -- 9409}, publisher = {Wiley-Blackwell}, title = {{Persistence and temporal compression of spike sequences during fast field oscillation in the hippocampus}}, volume = {10}, year = {1998}, } @article{3527, author = {Jozsef Csicsvari and Czurkó, András and Hirase, Hajima and Buzsáki, György}, journal = {European Journal of Neuroscience}, number = {Suppl. 10}, pages = {2553 -- 2553}, publisher = {Wiley-Blackwell}, title = {{Monosynaptic interactions between CA1 Pyramidal cells and interneuron in the behaving rat}}, volume = {10}, year = {1998}, } @article{3535, author = {Hirase, Hajima and Czurkó, András and Jozsef Csicsvari and Buzsáki, György}, journal = {European Journal of Neuroscience}, number = {Suppl. 10}, pages = {9932 -- 9932}, publisher = {Wiley-Blackwell}, title = {{Hippocampal pyramidal neutrons “space-clamped” in a running wheel task: Place cells or path integrators?}}, volume = {10}, year = {1998}, } @inbook{3570, abstract = {Visualization of high-dimensional or large geometric data sets is inherently difficult, so we experiment with the use of audio to display the shape and connectivity of these data sets. Sonification is used as both an addition to and a substitution for the visual display. We describe a new algorithm called wave traversal that provides a necessary intermediate step to sonification of the data; it produces an ordered sequence of subsets, called waves, that allows us to map the data to time. In this paper we focus in detail on the mathematics of wave traversal, in particular, how wave traversal can be used as a discrete Morse function.}, author = {Axen, Ulrike and Edelsbrunner, Herbert}, booktitle = {Mathematical Visualization}, isbn = {9783662035672}, pages = {223 -- 236}, publisher = {Springer}, title = {{Auditory Morse analysis of triangulated manifolds}}, doi = {10.1007/978-3-662-03567-2_17}, year = {1998}, } @article{3627, abstract = {When a favourable mutation sweeps to fixation, those genes initially linked to it increase in frequency; on average, this reduces diversity in the surrounding region of the genome. In the first analysis of this 'hitch-hiking' effect, Maynard-Smith and Haigh followed the increase of the neutral allele that chanced to be associated with the new mutation in the first generation, and assumed that the subsequent increase was deterministic. Later analyses, based on either coalescence arguments, or on diffusion equations for the mean and variance of allele frequency, have also made one or both of these assumptions. In the early generations, stochastic fluctuations in the frequency of the selected allele, and coalescence of neutral lineages, can be accounted for correctly by following relationships between genes conditional on the number of copies of the favourable allele. This analysis shows that the hitch-hiking effect is increased because an allele that is destined to fix tends to increase more rapidly than exponentially. However, the identity generated by the selective sweep has the same form as in previous work, h[r/s] (2 Ns)(-2r/s), where h[r/s] tends to 1 with tight linkage. This analysis is extended to samples of many genes; then, genes may trace back to several families of lineages, each related through a common ancestor early in the selective sweep. Simulations show that the number and sizes of these families can (in principle) be used to make separate estimates of r/s and Ns.}, author = {Barton, Nicholas H}, issn = {0016-6723}, journal = {Genetical Research}, number = {2}, pages = {123 -- 133}, publisher = {Cambridge University Press}, title = {{The effect of hitch-hiking on neutral genealogies}}, doi = {10.1017/S0016672398003462}, volume = {72}, year = {1998}, } @article{3628, abstract = {Determining the way in which deleterious mutations interact in their effects on fitness is crucial to numerous areas in population genetics and evolutionary biology. For example, if each additional mutation leads to a greater decrease in log fitness than the last (synergistic epistasis), then the evolution of sex and recombination may be favored to facilitate the elimination of deleterious mutations. However, there is a severe shortage of relevant data. Three relatively simple experimental methods to test for epistasis between deleterious mutations in haploid species have recently been proposed. These methods involve crossing individuals and examining the mean and/or skew in log fitness of the offspring and parents. The main aim of this paper is to formalize these methods, and determine the most effective way in which tests for epistasis could be carried out. We show that only one of these methods is likely to give useful results: crossing individuals that have very different numbers of deleterious mutations, and comparing the mean log fitness of the parents with that of their offspring. We also reconsider experimental data collected on Chlamydomonas moewussi using two of the three methods. Finally, we suggest how the test could be applied to diploid species.}, author = {West, Stuart and Peters, Andrew and Barton, Nicholas H}, issn = {0016-6731}, journal = {Genetics}, number = {1}, pages = {435 -- 444}, publisher = {Genetics Society of America}, title = {{Testing for epistasis between deleterious mutations}}, doi = {10.1093/genetics/149.1.435}, volume = {149}, year = {1998}, }