Critical thermal maxima and thermal tolerance in small mammals.

The CTM was then used to compare the thermal tolerances of five species of small mammals (laboratory mice, Mus musculus; white-footed mice, Peromyscus leucopus; gerbils, Meriones unguiculatus; laboratory rats, Rattus norvegicus; kangaroo rats, Dipodomys ordi). All animals were acclimatized to 25 (+OR-) 1(DEGREES)C and an LD 12:12 photoperiod. The CTM of D. ordi was significantly higher than that of all other species. The CTM of M. musculus was lower than the CTM of all other species. The CTM of P. leucopus was lower than that of R. norvegicus. There was no difference in CTM between M. unguiculatus and R. norvegicus.The CTM appears to be an easily determined measure of thermal tolerance that can be applied to small mammals in much the way that the technique has been used with ectotherms. However, acclimatization and testing procedures should be standardized to allow meaningful comparisons in future studies.The critical thermal maximum (CTM) was used to assess thermal tolerance in Mus musculus acclimatized to two photoperiods (LD 12:12 or LD 18:06, photophase centered at 1200 CST) and four thermal regimes (15(DEGREES)C, 25(DEGREES)C, 30(DEGREES)C or a 15 to 30(DEGREES)C cycle, LD 12:12). Mice acclimatized to LD 12:12 (25 (+OR-) 1(DEGREES)C) had a unimodal diel cycle in CTM while mice exposed to LD 18:06 (25 (+OR-) 1(DEGREES)C) displayed a bimodal cycle in CTM. Acclimatization to constant temperatures (LD 12:12) had no effect on CTM but acclimatization to a cycling thermal regime significantly increased the CTM. These data support the suggestion of susceptibility-resistance cycles to heat stress and indicate that the CTM of endotherms can be altered by internal and external modifying factors

Large Cayley graphs of small diameter

The degree-diameter problem seeks to find the largest possible number of vertices in a graph having given diameter and given maximum degree. Very often the problem is studied for restricted families of graph such as vertex-transitive or Cayley graphs, with the goal being to find a family of graphs with good asymptotic properties. In this paper we restrict attention to Cayley graphs, and study the asymptotics by fixing a small diameter and constructing families of graphs of large order for all values of the maximum degree. Much of the literature in this direction is focused on the diameter two case. In this paper we consider larger diameters, and use a variety of techniques to derive new best asymptotic constructions for diameters 3, 4 and 5 as well as an improvement to the general bound for all odd diameters. Our diameter 3 construction is, as far as we know, the first to employ matrix groups over finite fields in the degree-diameter problem

On Total Regularity of Mixed Graphs with Order Close to the Moore Bound

The undirected degree/diameter and degree/girth problems and their directed analogues have been studied for many decades in the search for efficient network topologies. Recently such questions have received much attention in the setting of mixed graphs, i.e. networks that admit both undirected edges and directed arcs. The degree/diameter problem for mixed graphs asks for the largest possible order of a network with diameter $k$, maximum undirected degree $\leq r$ and maximum directed out-degree $\leq z$. Similarly one can search for the smallest possible $k$-geodetic mixed graphs with minimum undirected degree $\geq r$ and minimum directed out-degree $\geq z$. A simple counting argument reveals the existence of a natural bound, the Moore bound, on the order of such graphs; a graph that meets this limit is a mixed Moore graph. Mixed Moore graphs can exist only for $k = 2$ and even in this case it is known that they are extremely rare. It is therefore of interest to search for graphs with order one away from the Moore bound. Such graphs must be out-regular; a much more difficult question is whether they must be totally regular. For $k = 2$, we answer this question in the affirmative, thereby resolving an open problem stated in a recent paper of Lopez and Miret. We also present partial results for larger $k$. We finally put these results to practical use by proving the uniqueness of a 2-geodetic mixed graph with order exceeding the Moore bound by one

How paradoxical are the effects of thought suppression ? : the nature of mental control and the factors that influence it

This thesis attempted to expand knowledge of intentional thought control in several directions. The primary aim was to provide an account of intentional thought suppression by relating the phenomenon to the methods used to assess the rebound effect, internal personality factors and psychopathology. An additional aim was to examine the rebound effect from the broader perspective of relating thought suppression to aging, the perception of volitional control and memory for future intentions. The results indicate that the method used to index the rebound effect may have a large impact on whether the effect is found or not. The rebound effect was obtained with the original method of assessment (Wegner, 1987) but not with the modified method that is currently used in the research. More importantly, the rebound effect was affected by the personality variable of state vs. action orientation (Kuhl & Beckmann, 1994b). State oriented participants demonstrated the rebound effect, whereas action oriented participants did not, irrespective of the method used to assess the effect. This finding provides support for the new intentional account of the rebound effect proposed in the thesis that is based on the Intention Superiority Effect (Kuhl, 1994) and the theory of action control (Kuhl & Beckmann, 1994b). The results also showed that suppression and expression performance in the laboratory did not have a common underlying mechanism. Successful expression performance was related to poorer suppression performance and visa versa. The results of the thesis also question the validity of the White Bear Suppression Inventory (Wegner and Zanakos, 1994)a s a measure of the tendency to suppress thoughts in everyday life. In young adults, apart from thought suppression, it also appears to measure the tendency to experience thought intrusions (rumination). Moreover, there was no relationship between the use of thought suppression in everyday life and actual suppression performance in the laboratory.A different pattern of results were obtained in a group of older adults (over 65 years). In addition, older adults reported using thought suppression reliably less frequently than young adults (i. e. had lower WBSI scores), and displayed much higher levels of repressive coping style than young people, 37% (old) vs. 9.5% (young). Finally, the results showed that thought suppression can also have other ironic effects on behaviour and perception. Participants attempting to complete an action while suppressing thoughts of the intention to perform this action came to feel as if the act was less intentionally performed. In contrast, participants completing actions under thought expression instructions rated the actions as more intentional. Furthermore, suppressing or expressing thoughts of an upcoming intention did not help one to remember to enact the intention with an enhanced frequency relative to thinking about a completely unrelated intention. Taken together, the findings have important implications for research on thought suppression and mental control by showing that the rebound effect is less robust than suggested by previous research. Thus, some of the controversy surrounding the rebound effect can be explained on the basis of individual differences in personality type (state vs. action orientation) as well as the methods used to index the effect. The results also raise several important questions for future research in this area (e. g. the validity of WBSI, effects of age on thought suppression and repression)

I suppress, therefore I smoke : effects of thought suppression on smoking behavior

“The final, definitive version of this article has been published in the Journal, Psychological Science, Vol 21 issue 9, 2010, © SAGE Publications Ltd, 2010: on SAGE Journals Online: http://online.sagepub.com/Thought suppression is a method frequently employed by individuals who are trying to control their thoughts and behaviors. Although this strategy is known to actually increase unwanted thoughts, it is unclear whether thought suppression also results in behavioral rebound. The study presented in this article investigated the effects of suppressing thoughts of smoking in everyday life on the number of cigarettes subsequently smoked. Study participants recorded their daily cigarette intake and stress levels over a 3-week period. In Week 1 and Week 3, participants monitored intake and stress. During Week 2, in addition to monitoring intake and stress, participants in the experimental groups either suppressed or expressed smoking thoughts, whereas the control group continued monitoring. Our results showed a clear behavioral rebound: The suppression group smoked significantly more in Week 3 than the expression or control group did. Moreover, the tendency to suppress thoughts (measured by the White Bear Suppression Inventory) was positively related to the number of attempts to quit smoking. The implications of our findings for smoking cessation are discussed.Peer reviewe

Mutually avoiding Eulerian circuits

Two Eulerian circuits, both starting and ending at the same vertex, are avoiding if at every other point of the circuits they are at least distance 2 apart. An Eulerian graph which admits two such avoiding circuits starting from any vertex is said to be doubly Eulerian. The motivation for this definition is that the extremal Eulerian graphs, i.e. the complete graphs on an odd number of vertices and the cycles, are not doubly Eulerian. We prove results about doubly Eulerian graphs and identify those that are the `densest' and `sparsest' in terms of the number of edges.Comment: 22 pages; 9 figure

Selective Solvent Extraction of Tantalum and Niobium Fluorides Using N-Benzoyl-N-Phenylhydroxylamine

Chemistr

High-resolution broadband spectroscopy using externally dispersed interferometry at the Hale telescope: part 2, photon noise theory

High-resolution broadband spectroscopy at near-infrared (NIR) wavelengths (950 to 2450 nm) has been performed using externally dispersed interferometry (EDI) at the Hale telescope at Mt. Palomar, with the TEDI interferometer mounted within the central hole of the 200-in. primary mirror in series with the comounted TripleSpec NIR echelle spectrograph. These are the first multidelay EDI demonstrations on starlight. We demonstrated very high (10×) resolution boost and dramatic (20× or more) robustness to point spread function wavelength drifts in the native spectrograph. Data analysis, results, and instrument noise are described in a companion paper (part 1). This part 2 describes theoretical photon limited and readout noise limited behaviors, using simulated spectra and instrument model with noise added at the detector. We show that a single interferometer delay can be used to reduce the high frequency noise at the original resolution (1× boost case), and that except for delays much smaller than the native response peak half width, the fringing and nonfringing noises act uncorrelated and add in quadrature. This is due to the frequency shifting of the noise due to the heterodyning effect. We find a sum rule for the noise variance for multiple delays. The multiple delay EDI using a Gaussian distribution of exposure times has noise-to-signal ratio for photon-limited noise similar to a classical spectrograph with reduced slitwidth and reduced flux, proportional to the square root of resolution boost achieved, but without the focal spot limitation and pixel spacing Nyquist limitations. At low boost (∼1×) EDI has ∼1.4× smaller noise than conventional, and at >10× boost, EDI has ∼1.4× larger noise than conventional. Readout noise is minimized by the use of three or four steps instead of 10 of TEDI. Net noise grows as step phases change from symmetrical arrangement with wavenumber across the band. For three (or four) steps, we calculate a multiplicative bandwidth of 1.8:1 (2.3:1), sufficient to handle the visible band (400 to 700 nm, 1.8:1) and most of TripleSpec (2.6:1)

Small Graphs and Hypergraphs of Given Degree and Girth

The search for the smallest possible d-regular graph of girth g has a long history, and is usually known as the cage problem. This problem has a natural extension to hypergraphs, where we may ask for the smallest number of vertices in a d-regular, r-uniform hypergraph of given (Berge) girth g. We show that these two problems are in fact very closely linked. By extending the ideas of Cayley graphs to the hypergraph context, we find smallest known hypergraphs for various parameter sets. Because of the close link to the cage problem from graph theory, we are able to use these techniques to find new record smallest cubic graphs of girths 23, 24, 28, 29, 30, 31 and 32