Male Dominance and Sexual Selection in the Crayfish Orconectes quinebaugensis

In many taxa, social structures are mediated by agonistic interactions and the formation of dominance hierarchies. In crayfish, dominance hierarchies may have evolved as a result sexual selection, allowing dominant males greater access to females, thereby increasing their reproductive success. This work tests the hypothesis that high male investment in dominance interactions may have evolved as a result of intra- and/or inter-sexual selection pressures by testing specific predictions in two parts: first, that reproductive males would invest more in agonistic interactions than reproductive females or non-reproductive members of both sexes; and second, that females would prefer odors of dominant males over subordinates, and that dominant males would be either more efficient at mating or be able to mate longer than subordinates. Investment in agonistic interactions was examined in intrasexual pairs of male and female crayfish in both the reproductive and non-reproductive season. As predicted, reproductive males invested more in agonistic interactions overall than reproductive females, while there was no significant difference in investment by non-reproductive males or females. However, no significant difference was found in agonistic investment between reproductive males and non-reproductive males. These data indicate that investment in agonism differs by sex and by reproductive status, and may indicate that dominance interactions are under sexual selection in males. Alternatively, this differential investment may be explained by seasonal changes in the individual costs and benefits of agonism, or by depressed investment by reproductive females. Female odor preference was tested using a y-maze containing control and male treated water. For tests of male mating, time spent in each of three stages of mating was recorded for male-female pairs. Of these tests, the only significant trend produced was that dominant males spent more time associated with the female during and after copulation than subordinates. This may indicate an advantage in fertilization success for males through decreased sperm competition. A pilot study was also conducted testing the predictions that females mated to dominant males invest more in offspring than those mated to subordinates and that such offspring have greater survivability, but no significant conclusions could be drawn from these data

Observation and Modeling of Coronal "Moss" With the EUV Imaging Spectrometer on Hinode

Observations of transition region emission in solar active regions represent a powerful tool for determining the properties of hot coronal loops. In this Letter we present the analysis of new observations of active region moss taken with the Extreme Ultraviolet Imaging Spectrometer (EIS) on the \textit{Hinode} mission. We find that the intensities predicted by steady, uniformly heated loop models are too intense relative to the observations, consistent with previous work. To bring the model into agreement with the observations a filling factor of about 16% is required. Furthermore, our analysis indicates that the filling factor in the moss is nonuniform and varies inversely with the loop pressure

Constraints on the Heating of High Temperature Active Region Loops: Observations from Hinode and SDO

We present observations of high temperature emission in the core of a solar active region using instruments on Hinode and SDO. These multi-instrument observations allow us to determine the distribution of plasma temperatures and follow the evolution of emission at different temperatures. We find that at the apex of the high temperature loops the emission measure distribution is strongly peaked near 4 MK and falls off sharply at both higher and lower temperatures. Perhaps most significantly, the emission measure at 0.5 MK is reduced by more than two orders of magnitude from the peak at 4 MK. We also find that the temporal evolution in broad-band soft X-ray images is relatively constant over about 6 hours of observing. Observations in the cooler SDO/AIA bandpasses generally do not show cooling loops in the core of the active region, consistent with the steady emission observed at high temperatures. These observations suggest that the high temperature loops observed in the core of an active region are close to equilibrium. We find that it is possible to reproduce the relative intensities of high temperature emission lines with a simple, high-frequency heating scenario where heating events occur on time scales much less than a cooling time. In contrast, low-frequency heating scenarios, which are commonly invoked to describe nanoflare models of coronal heating, do not reproduce the relative intensities of high temperature emission lines and predict low-temperature emission that is approximately an order of magnitude too large. We also present an initial look at images from the SDO/AIA 94 A channel, which is sensitive to Fe XVIII.Comment: Movies are available at http://tcrb.nrl.navy.mil/~hwarren/temp/papers/active_region_core/ Paper has been refereed and revise

Evidence for Steady Heating: Observations of an Active Region Core with Hinode and TRACE

Previous observations have not been able to exclude the possibility that high temperature active region loops are actually composed of many small scale threads that are in various stages of heating and cooling and only appear to be in equilibrium. With new observations from the EUV Imaging Spectrometer (EIS) and X-ray Telescope (XRT) on \textit{Hinode} we have the ability to investigate the properties of high temperature coronal plasma in extraordinary detail. We examine the emission in the core of an active region and find three independent lines of evidence for steady heating. We find that the emission observed in XRT is generally steady for hours, with a fluctuation level of approximately 15% in an individual pixel. Short-lived impulsive heating events are observed, but they appear to be unrelated to the steady emission that dominates the active region. Furthermore, we find no evidence for warm emission that is spatially correlated with the hot emission, as would be expected if the high temperature loops are the result of impulsive heating. Finally, we also find that intensities in the "moss", the footpoints of high temperature loops, are consistent with steady heating models provided that we account for the local expansion of the loop from the base of the transition region to the corona. In combination, these results provide strong evidence that the heating in the core of an active region is effectively steady, that is, the time between heating events is short relative to the relevant radiative and conductive cooling times.Comment: Minor changes based on the final report from the referee; Movies are available from the first autho

Characteristics and Evolution of the Magnetic field and Chromospheric Emission in an Active Region Core Observed by Hinode

We describe the characteristics and evolution of the magnetic field and chromospheric emission in an active region core observed by the Solar Optical Telescope on Hinode. Consistent with previous studies, we find that the moss is unipolar, the spatial distribution of magnetic flux evolves slowly, and the magnetic field is only moderately inclined. We show that the field line inclination and horizontal component are coherent, and that the magnetic field is mostly sheared in the inter-moss regions where the highest magnetic flux variability is seen. Using extrapolations from SP magnetograms we show that the magnetic connectivity in the moss is different than in the quiet Sun because most of the magnetic field extends to significant coronal heights. The magnetic flux, field vector, and chromospheric emission in the moss also appear highly dynamic, but actually show only small scale variations in magnitude on time-scales longer than the cooling times for hydrodynamic loops computed from our extrapolations, suggesting high-frequency (continuous) heating events. Some evidence is found for flux (Ca 2 intensity) changes on the order of 100--200 G (DN) on time-scales of 20--30 mins that could be taken as indicative of low-frequency heating. We find, however, that only a small fraction (10%) of our simulated loops would be expected to cool on these time-scales, and we find no clear evidence that the flux changes consistently produce intensity changes in the chromosphere. The magnetic flux and chromospheric intensity in most individual SOT pixels in the moss vary by less than ~ 20% and ~ 10%, respectively, on loop cooling time-scales. In view of the high energy requirements of the chromosphere, we suggest that these variations could be sufficient for the heating of `warm' EUV loops, but that the high basal levels may be more important for powering the hot core loops rooted in the moss.Comment: Accepted by ApJ, 16 pages, 20 figures. Abridged abstract (original is in PDF file). Figures 1 & 2 are reduced resolution to meet size limit

Using a Differential Emission Measure and Density Measurements in an Active Region Core to Test a Steady Heating Model

The frequency of heating events in the corona is an important constraint on the coronal heating mechanisms. Observations indicate that the intensities and velocities measured in active region cores are effectively steady, suggesting that heating events occur rapidly enough to keep high temperature active region loops close to equilibrium. In this paper, we couple observations of Active Region 10955 made with XRT and EIS on \textit{Hinode} to test a simple steady heating model. First we calculate the differential emission measure of the apex region of the loops in the active region core. We find the DEM to be broad and peaked around 3\,MK. We then determine the densities in the corresponding footpoint regions. Using potential field extrapolations to approximate the loop lengths and the density-sensitive line ratios to infer the magnitude of the heating, we build a steady heating model for the active region core and find that we can match the general properties of the observed DEM for the temperature range of 6.3 $<$ Log T $<$ 6.7. This model, for the first time, accounts for the base pressure, loop length, and distribution of apex temperatures of the core loops. We find that the density-sensitive spectral line intensities and the bulk of the hot emission in the active region core are consistent with steady heating. We also find, however, that the steady heating model cannot address the emission observed at lower temperatures. This emission may be due to foreground or background structures, or may indicate that the heating in the core is more complicated. Different heating scenarios must be tested to determine if they have the same level of agreement.Comment: 16 pages, 9 figures, accepted to Ap

Cytotoxicity of Poly(Phenolic)Sulfonates and Their Sodium Salts in L1210 Lymphoid Leukemia Cells

Poly(phenolic)-sulfonates demonstrated very good cytotoxicity against the growth of tumor cell lines (L1210, Tmolt-3, HeLa-S3) and are comparable in potency with typical clinically used anticancer drugs. Four of the most active compounds, i.e. GL-2021, GL-2029, GL-2041 and GL-2063, were selected for a mode of action study in L1210 lymphoid leukemia cells at concentration of 25μM to 100μM for 60 min. The agents did not alkylate bases of ct-DNA, cause intercalation between base pairs, produce cross linking of ct-DNA strands or generate free radicals although L1210 DNA fragmentation was observed after 24 hr incubation. L1210 DNA synthesis was preferentially inhibited which was achieved by (1) suppressing DNA polymerase α activity which reduced the synthesis of new strands of DNA, (2) reducing of de novo purine synthesis at the regulatory enzyme PRPP amido transferase which reduced d(GMP) levels, and (3) inhibiting of nucleoside kinase activities which further reduced DNA synthesis. DNA template activity was altered by the poly(phenolic)sulfonates since they reduced DNA polymerase α and m-RNA and t-RNA polymerase activities. The kinetic studies at 50 μM over 2 hr demonstrated that the agents’ effect on PRPP-amido transferase activity is probably a major target of the compounds

Phylogeny of the Sepia officinalis species complex in the east Atlantic extends the known distribution of Sepia vermiculata across the Benguela upwelling region

Accurate species identification and biogeographic characterisation are fundamental for appropriate management of expanding cephalopod fisheries. This study addresses this topic within the common cuttlefish Sepia officinalis species complex (S. officinalis, S. hierredda and S. vermiculata), with an emphasis on occurrence in African waters. Tissue samples from the currently presumed distributions of S. vermiculata and S. hierredda (from South Africa and Ghana/Angola, respectively) were sequenced for the cytochrome c oxidase subunit I (COI) and the cytochrome b (cytb) genes of the mitochondrial genome and then compared to existing S. officinalis sequences. Three highly divergent and reciprocally monophyletic clades, corresponding to S. officinalis, S. hierredda and S. vermiculata, were resolved, representing the first molecular confirmation of the distinct species status of S. hierredda and S. vermiculata. The sequences also revealed that, contrary to expectations based on presently published information, all samples from southern Angola were S. vermiculata. These results indicate that the range of S. vermiculata extends beyond the currently described northern limit and that S. hierredda and S. vermiculata may be indiscriminately harvested in Angolan waters. Finer-scale patterns within S. vermiculata phylogeography also indicate that the Benguela Current System and/or other environmental factors serve to isolate northern and southern stocks