Topological triviality of smoothly knotted surfaces in 4-manifolds

Some generalizations and variations of the Fintushel-Stern rim surgery are known to produce smoothly knotted surfaces. We show that if the fundamental groups of their complements are cyclic, then these surfaces are topologically unknotted. Using a twist-spinning construction from high-dimensional knot theory, we construct examples of knotted surfaces whose complements have cyclic fundamental groups.Comment: Final version; appeared in AMS Transactions. 15 pages, 2 figure

Double point surgery and configurations of surfaces

We introduce a new operation, double point surgery, on immersed surfaces in a 4-manifold, and use it to construct knotted configurations of surfaces in many 4-manifolds. Taking branched covers, we produce smoothly exotic actions of Z/m x Z/n on simply connected 4-manifolds with complicated fixed-point sets.Comment: Final version; to appear in Journal of Topology. Removed assertion about the restriction of the Z/m x Z/n action to the Z/m and Z/n subgroup

Self-heating of Strongly Interacting Massive Particles

It was recently pointed out that semi-annihilating dark matter (DM) may experience a novel temperature evolution dubbed as self-heating. Exothermic semi-annihilation converts the DM mass to the kinetic energy. This yields a unique DM temperature evolution, $T_{\chi} \propto 1 / a$, in contrast to $T_{\chi} \propto 1 / a^{2}$ for free-streaming non-relativistic particles. Self-heating continues as long as self-scattering sufficiently redistributes the energy of DM particles. In this paper, we study the evolution of cosmological perturbations in self-heating DM. We find that sub-GeV self-heating DM leaves a cutoff on the subgalactic scale of the matter power spectrum when the self-scattering cross section is $\sigma_{\rm self} / m_{\chi} \sim {\cal O} (1) \,{\rm cm}^{2} /{\rm g}$. Then we present a particle physics realization of the self-heating DM scenario. The model is based on recently proposed strongly interacting massive particles with pion-like particles in a QCD-like sector. Pion-like particles semi-annihilate into an axion-like particle, which is thermalized with dark radiation. The dark radiation temperature is smaller than the standard model temperature, evading the constraint from the effective number of neutrino degrees of freedom. It is easily realized when the dark sector is populated from the standard model sector through a small coupling.Comment: 25 pages, 5 figures; minor corrections, version accepted in PR

Decaying axinolike dark matter: Discriminative solution to small-scale issues

The latest Lyman-$\alpha$ forest data severely constrain the conventional warm dark matter solution to small-scale issues in the cold dark matter paradigm. It has been also reported that unconstrained astrophysical processes may address the issues. In response to this situation, we revisit the decaying dark matter solution to the issues, discussing possible signatures to discriminate decaying dark matter from astrophysical processes as a solution to small-scale issues. We consider an axinolike particle (ALPino) decaying into an axionlike particle (ALP) and gravitino with the lifetime around the age of the Universe. The ALPino mass is sub-PeV and slightly ($\Delta m/m\sim 10^{-4}$) larger than the gravitino mass, and thus the dark matter abundance does not alter virtually after the ALPino decays. On the other hand, the gravitino produced from the ALPino decay obtains a kick velocity of $\sim 30 \,{\rm km / s}$, which is sufficiently larger than a circular velocity of dwarf galaxies to impact their dark matter distributions. The Lyman-$\alpha$ forest constraints are relieved since only a small fraction ($\sim10$%) of dark matter experiences the decay at that time. Decaying dark matter is thus promoted to a viable solution to small-scale issues. The ALPino relic abundance is determined predominantly by the decay of the lightest ordinary supersymmetric particle. The monochromatic ALP emission from the ALPino decay is converted to $\sim 50 \,{\rm GeV}$ photon under the Galactic magnetic field. The morphology of the gamma-ray flux shows a distinctive feature of the model when compared to decaying dark matter that directly decays into photons. Once detected, such distinctive signals discriminate the decaying dark matter solution to small-scale issues from unconstrained astrophysical processes.Comment: 6 pages, 3 figures; discussions improved, version accepted in PR

Self-heating dark matter via semi-annihilation

The freeze-out of dark matter (DM) depends on the evolution of the DM temperature. The DM temperature does not have to follow the standard model one, when the elastic scattering is not sufficient to maintain the kinetic equilibrium. We study the temperature evolution of the semi-annihilating DM, where a pair of the DM particles annihilate into one DM particle and another particle coupled to the standard model sector. We find that the kinetic equilibrium is maintained solely via semi-annihilation until the last stage of the freeze-out. After the freeze-out, semi-annihilation converts the mass deficit to the kinetic energy of DM, which leads to non-trivial evolution of the DM temperature. We argue that the DM temperature redshifts like radiation as long as the DM self-interaction is efficient. We dub this novel temperature evolution as self-heating. Notably, the structure formation is suppressed at subgalactic scales like keV-scale warm DM but with GeV-scale self-heating DM if the self-heating lasts roughly until the matter-radiation equality. The long duration of the self-heating requires the large self-scattering cross section, which in turn flattens the DM density profile in inner halos. Consequently, self-heating DM can be a unified solution to apparent failures of cold DM to reproduce the observed subgalactic scale structure of the Universe.Comment: 6 pages, 4 figures. v2: discussed improved, matches published versio

Formation of Multiple Dimer Interfaces in the Active and Inactive States of a Model G Protein-Coupled Receptor

G protein-coupled receptors (GPCRs) are a class of integral membrane receptor proteins that are characterized by seven-transmembrane (7TM) domains connected by intracellular and extracellular loops, an extracellular N-terminus, and an intracellular Cterminus. GPCRs recognize neurotransmitters, sensory molecules and chemotactic agents and are involved in the control of many aspects of metabolism. Since GPCRs play important roles in diverse processes such as pain perception, growth and blood pressure regulation, and viral pathogenesis, GPCRs became important target for therapeutic agents. The tridecapeptide α-factor pheromone (W1H2W3L4Q5L6K7P8G9Q10P11M12Y13) of Saccharomyces cerevisiae and Ste2p, its cognate GPCR, have been used extensively as a model for peptide ligand-GPCR structure and function. The power of yeast genetics has been used to examine the structure and function of Ste2p. Recently, GPCR homodimerization has been demonstrated for many GPCRs, although the role(s) of dimerization in receptor function is disputed. In this dissertation, Ste2p has been used to investigate GPCR dimerization. Part I of this dissertation is an overview of the GPCR structure and its ligandinduced conformational change with specific emphasis on the peptide pheromone α- factor and its receptor Ste2p. Part II of this dissertation is a study originally designed to probe inter-helical interaction between TM1 and TM7 of Ste2p. Site-directed mutagenesis and cysteine cross-linking with targeted residues of Ste2p were carried out. Although the anticipated inter-helical interactions were not identified from this study, the results provided strong evidence for Ste2p dimerization. Part III of this dissertation describes dimer interfaces including TM1 and TM7 of Ste2p. By using the disulfide cross-linking methodology, we studied the participation of specific residues at the intracellular boundary between TM1 and intracellular loop one and the entire TM7 in Ste2p dimerization. The final part of this dissertation contains a study of the participation of the Ste2p N-terminus in homo-dimer formation and the effect of ligand binding on this interaction. This part also includes overall conclusions and suggestions for future experiments that could contribute to an understanding of the dimer interfaces in Ste2p and the role of dimerization in the function of this receptor

Habitat-Host-Vector Interactions of Ornithodoros turicata Dugès (Ixodida: Argasidae) in Texas, USA.

Ticks (Class Arachnida: Order Ixodida) are obligatory ectoparasites with diverse vertebrate host groups and vectors of more than 35 human and zoonotic pathogens, which causes untold economic damages. For the past several decades, applications of ecological principles based on tick-host-pathogen interactions have led to the development of effective and efficient tick surveillance and control. However, the progression in tick ecological studies has been largely in Ixodid and not in Argasid ticks. Ornithodoros turicata Dugès (Ixodida: Argasidae) is well established as a vector and reservoir of Borrelia turicatae, the causative agent of Tick-Borne Relapsing Fever. Furthermore, O. turicata is capable of transmitting African swine fever virus, an acute hemorrhagic disease of swine with global implications. Nevertheless, the ecology of O. turicata is poorly understood. The studies conducted in this dissertation determined the O. turicata habitat-host-vector interactions in TX via field observations at the cave environments, immunoassays of O. turicata challenge host sera, and two types of bloodmeal analysis techniques. The O. turicata habitat studies were conducted in 2015-2016 at the caves of Government Canyon State Natural State Area, TX. The study revealed that O. turicata are active year around with peak activities in the months of June and August. Moreover, the relative humidity and temperature profiles among four O. turicata-active caves in GCSNA remain similar in their values and pattern changes throughout the year. Also, activities of 20 vertebrate animals species, of which only seven were the previously known hosts of O. iii turicata, were noted. There were no correlations among the O. turicata phenology and relative humidity nor animal activities. However, there were significant correlations between O. turicata phenology and temperatures throughout the year. The enzyme-linked immunosorbent assays of O. turicata challenged domestic pig sera against O. turicata salivary gland extract (SGE) showed a significant increase in the production of immunoglobulin G (IgG) production against SGE as early as three weeks post-challenge. Up to 8,000 fold increase in IgG production in some of the O. turicata challenged pigs were observed. Western blot showed post challenge pig sera began reacting with SGE protein(s), size 25kDa, starting three weeks post-challenge. The bloodmeal analyses of O. turicata fed on chicken, goat, and swine blood using a qPCR method showed that O. turicata could retain cytochrome b (cytb) genes of hosts beyond 330 days through multiple molting. Also, the qPCR-based bloodmeal analyses could discern ctyb genes of multiple hosts if O. turicata had taken bloodmeals from multiple hosts. The bloodmeal analyses based on stable isotopic ratios of Carbon (δ¹³C) and Nitrogen (δ¹⁵N) in O. turicata generated unique δ¹³C and δ¹⁵N signatures based on the host blood consumed. However, the stable isotope analyses were not able to discern O. turicata which acquired multiple host bloodmeals

Potential application of a Gulf Coast Tick, Amblyomma maculatum Koch, Aggregation-Attachment-Pheromone for surveillance of free-living adults

The aggregation-attachment-pheromone (AAP) of two geographic strains of the Gulf Coast tick, Amblyomma maculatum Koch, was investigated to evaluate practicality of using solid-phase-microextraction (SPME) in an AAP study of Gulf Coast tick. Solid-phase microextraction was used to compare the AAP production in two strains of fed male Gulf Coast tick and demonstrate and confirm the presence of AAP in bioassays. A solid-phase-microextraction (SPME) headspace collection technique was sufficient to capture volatile organic compounds produced by fed and unfed male Gulf Coast ticks. Gas chromatography analysis revealed three major volatile organic compounds were produced in significantly greater amounts (p < 0.05) by fed males than those produced by unfed males. These volatile compounds were produced in significantly higher amount by the third day of feeding by male ticks. However, two of these volatiles remained relatively constant in their production while the primary volatile compound increased in its production until the eighth day of feeding by male Gulf Coast ticks. Also, the relative abundances of these three volatile organic compounds were different between Oklahoma and Texas strains of Gulf Coast ticks. The activity of AAP from fed male Gulf Coast ticks was confirmed using two bioassay techniques. A petri dish bioassay revealed significantly higher numbers of female Gulf Coast ticks attracted to fed-males which also produced significantly greater amounts (p < 0.001) of volatile organic compounds detected by GC analysis. The Ytube olfactometer bioassay revealed that significantly higher numbers of females responded to fed-males or to CO2 when compared to purified air (p < 0.001), but the differences in female response to fed-males and CO2 were not significant (p < 0.391 in Oklahoma strain and p < 0.458 in Texas strain). However, female responses to stimuli containing both fed-males and CO2 were significantly higher when compared to either stimulus alone (p < 0.001)