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We investigate the reorientation dynamics of four octanol isomers with very different characteristics regarding the formation of hydrogen-bonded structures by means of photon-correlation spectroscopy (PCS) and broadband dielectric spectroscopy. PCS is largely insensitive to orientational cross-correlations and straightforwardly probes the α-process dynamics, thus allowing us to disentangle the complex dielectric relaxation spectra. The analysis reveals an additional dielectric relaxation contribution on time scales between the structural α-process and the Debye process. In line with nuclear magnetic resonance results from the literature and recent findings from rheology experiments, we attribute this intermediate contribution to the dielectric signature of the O–H bond reorientation. Due to being incorporated into hydrogen-bonded suprastructures, the O–H bond dynamically decouples from the rest of the molecule. The relative relaxation strength of the resulting intermediate contribution depends on the respective position of the hydroxy group within the molecule and seems to vanish at sufficiently high temperatures, i.e., exactly when the overall tendency to form hydrogen bonded structures decreases. Furthermore, the fact that different octanol isomers share the same dipole density allows us to perform an in-depth analysis of how dipolar cross-correlations appear in dielectric loss spectra. We find that dipolar cross-correlations are not solely manifested by the presence of the slow Debye process but also scale the relaxation strength of the self-correlation contribution depending on the Kirkwood factor. [ABSTRACT FROM AUTHOR]

Genetic relationships were examined among wild-caught southern flying squirrels (Glaucomys volans) sharing the same natural nest cavity. Under natural conditions, typically 75-80% of southern flying squirrel nest groups comprise adult-aged individuals. The remainder nest in family-based groups or are solitary. The coefficient of relatedness within nest groups of adult individuals and family-based nest groups was examined through microsatellite DNA analysis. Family or adult nest groups were identified from the age class of individual group members determined through a discriminant function analysis based on body mass. From this information, nest groups were categorized as family-based groups comprising a single adult female with nestlings, adult groups comprising adult aged-individuals, or subadult nest groups. The average coefficient of relatedness was determined in each nest group. Within the putative family groups, most individuals were 1st-order relatives. In the adult nest groups, the coefficient of relatedness was low, indicating that these individuals were unrelated. The relationships within the subadult nest groups were intermediate. This is the 1st study to show that adult nestmate southern flying squirrels typically are unrelated and do not nest in family-based groups. Key words: coefficient of relatedness, discriminant function analysis, group nesting, microsatellite DNA

Glass-forming liquids are well known to have significant dynamic heterogeneities, leading to spatially grossly varying elastic properties throughout the system. In this paper, we compare the local elastic response of supercooled 1-propanol monitored by triplet state solvation dynamics to the macroscopic dynamic shear modulus measured by a piezo-electric gauge. The time-dependent responses are found to be identical, which means that the dynamic macroscopic shear modulus provides a good measure of the average local elastic properties. Since the macroscopic shear modulus of a dynamically inhomogeneous system in general is not just the average of the local moduli, there was no reason to expect such a result. This surprising finding not only provides constraints for models of dynamical heterogeneities in glass-forming liquids, but also allows for a fairly straightforward check on elastic models for glassy dynamics. [ABSTRACT FROM AUTHOR]

We suggest a way to disentangle self- from cross-correlation contributions in the dielectric spectra of glycerol. Recently it was demonstrated for monohydroxy alcohols that a detailed comparison of the dynamic susceptibilities of photon correlation and broadband dielectric spectroscopy allows to unambiguously disentangle a collective relaxation mode known as the Debye process, which arises due to supramolecular structures, and the α-relaxation, which proves to be identical in both methods. In the present paper, we apply the same idea and analysis to the paradigmatic glass former glycerol. For that purpose we present new light scattering data from photon correlation spectroscopy measurements and combine these with literature data to obtain a data set covering a dynamic range from 10−4–1013 Hz. Then we apply the above mentioned analysis by comparing this data set with a corresponding set of broadband dielectric data. Our finding is that even in a polyalcohol self- and cross-correlation contributions can approximately be disentangled in that way and that the emerging picture is very similar to that in monohydroxy alcohols. This is further supported by comparing the data with fast field cycling NMR measurements and dynamic shear relaxation data from the literature, and it turns out that, within the described approach, the α-process appears very similar in all methods, while the pronounced differences observed in the spectral density are due to a different expression of the slow collective relaxational contribution. In the dielectric spectra the strength of this peak is reasonably well estimated by the Kirkwood correlation factor, which supports the view that it arises due to dynamic cross-correlations, which were previously often assumed to be negligible in dielectric measurements. [ABSTRACT FROM AUTHOR]

The dielectric Debye relaxation in monohydroxy alcohols has been subject of long-standing scientific interest and is presently believed to arise from the relaxation of transiently H-bonded supramolecular structures. Therefore, its manifestation in a measurement with a local dielectric probe might be expected to be different from the standard macroscopic dielectric experiment. In this work we present such local dielectric measurements obtained by triplet state solvation dynamics (TSD) and compare the results with macroscopic dielectric and light scattering data. In particular, with data from an improved TSD setup, a detailed quantitative comparison reveals that the Debye process does not significantly contribute to the local Stokes shift response function, while α- and β-relaxations are clearly resolved. Furthermore, this comparison reveals that the structural relaxation has almost identical time constants and shape parameters in all three measurement techniques. Altogether our findings support the notion that the transiently bound chain structures lead to a strong cross-correlation contribution in macroscopic dielectric experiments, to which both light scattering and TSD are insensitive, the latter due to its local character and the former due to the molecular optical anisotropy being largely independent of the OH bonded suprastructures. [ABSTRACT FROM AUTHOR]

We have developed a flexible experimental setup to conduct triplet solvation dynamics (TSD) experiments. The setup is capable of exciting dyes at 355, 320 and 266 nm. Phosphorescence spectra can be recorded up to a 10 ns-resolution usually covering three decades using a grating spectrograph and a CCD camera. In this contribution, we describe the experimental setup as well as first investigations on water-alcohol mixtures, microemulsions and new dyes for TSD, i.e. naphthalene derivates, which take full advantage of this experimental method sensitive to the local environment of the dyes. [ABSTRACT FROM AUTHOR]

We examined the proximate mechanisms of cache retrieval in the group-living, southern flying squirrel, Glaucomys volans, through a series of behavioral experiments conducted in a large indoor arena. The effectiveness of several retrieval mechanisms was determined including spatial memory, olfaction, random searching and a heuristic under different environmental conditions. Our goal was to elucidate the hoarding strategy of individuals in a nest group and to address whether food storing individuals possess a retrieval advantage over pilfering nestmates. A storer's retrieval advantage is necessary for scatter hoarding to be an evolutionarily stable strategy (ESS) within aggregations of unrelated individuals. Our previous work has shown that, G. volans lives in such groups, and consequently it was important to address the storer's retrieval advantage under a range of environmental conditions. Initially in our baseline experiment, we developed methods to eliminate olfactory-based retrieval and to control for random searching. Subsequently, we experimentally determined the effectiveness of cache retrieval via spatial memory, a heuristic and olfaction. We examined the mechanisms of cache retrieval in three additional experiments using two independent subject populations and found that under dry, odorless conditions spatial memory was the most effective retrieval mechanism in support of a storer's retrieval advantage. In a fifth experiment we examined cache retrieval under wet environmental conditions and showed that olfactory-based retrieval was effective and the storer's advantage was reduced. We interpret these laboratory results based on considerations of natural environmental conditions and game theory. We propose a conditional ESS strategy where animals store and retrieve their own caches as the primary food hoarding tactic and opportunistically pilfer caches as a secondary tactic. [ABSTRACT FROM AUTHOR]

We assessed the genetic status of two endangered subspecies of the northern flying squirrel (Glaucomys sabrinus) that are restricted to isolated stands of high elevation spruce-fir and adjacent spruce-fir-hardwood ecotonal habitat in the Appalachian Mountains of eastern North America. We used mitochondrial DNA (mtDNA) and allozyme data to estimate levels of genetic variability in the two subspecies of interest and then evaluated this information in the context of large-scale phylogeographical structure and overall genetic variability for the entire species and for the closely related and partially sympatric southern flying squirrel (Glaucomys volans). This broader analysis involves much of North America's northern coniferous forest biome, together with the deciduous forest biome of eastern North America. Our results support the evolutionary distinctness of the endangered Appalachian populations of G. sabrinus. These populations possess several private alleles and have levels of genetic variability that are substantially lower than those observed in conspecific populations found elsewhere. However, the endangered Appalachian populations of G. sabrinus have higher levels of genetic variability than those observed in populations of G. volans from across eastern North America. These results highlight the utility of evaluating the conservation genetics of small and isolated populations within a broad-scale comparative evolutionary and biogeographical framework. [ABSTRACT FROM AUTHOR]

Presents a study that investigated the function and capacities of the hindlimbs and talons of several species of sympatric raptors. Background on the basic raptor form and function; Examination of the bone and muscle structure of the raptor limb; Analysis of grip force measurements.

Photoluminescence is known to have huge potential for applications in studying biological systems. In that respect, phosphorescent dye molecules open the possibility to study the local slow solvent dynamics close to hard and soft surfaces and interfaces using the triplet state (TSD: triplet state solvation dynamics). However, for that purpose, probe molecules with efficient phosphorescence features are required with a fixed location on the surface. In this article, a potential TSD probe is presented in the form of a nanocomposite: we synthesize spherical silica particles with 2-naphthalene methanol molecules attached to the surface with a predefined surface density. The synthesis procedure is described in detail, and the obtained materials are characterized employing transmission electron microscopy imaging, Raman, and X-ray photoelectron spectroscopy. Finally, TSD experiments are carried out in order to confirm the phosphorescence properties of the obtained materials and the route to develop phosphorescent sensors at silica surfaces based on the presented results is discussed. [ABSTRACT FROM AUTHOR]

Proposes the prehistoric origins of grass bald or high altitude treeless expanses in the southern Appalachian region. Use of the grass balds by American Indians and early white settlers; Threat posed by the grass balds to plant and animal communities in the region; Possible role of mammalian herbivores during the Pleistocene Era in the creation of the grass balds.

The nonexponential shape of the α process observed in supercooled liquids is considered as one of the hallmarks of glassy dynamics and has thus been under study for decades, but is still poorly understood. For a polar van der Waals liquid, we show here--in line with a recent theory--that dipole-dipole correlations give rise to an additional process in the dielectric spectrum slightly slower than the α relaxation, which renders the resulting combined peak narrower than observed by other experimental techniques. This is reminiscent of the Debye-process found in monohydroxy alcohols. The additional peak can be suppressed by weakening the dipole-dipole interaction via dilution with a nonpolar solvent. [ABSTRACT FROM AUTHOR]

Triplet state solvation dynamics (TSD) is a truly local measurement technique, where a dye molecule is dissolved as a probe at low concentration in a solvent. Depending on the dye molecule, local information on mechanical or dielectric solvation can be obtained. So far, this method has mainly been used to investigate topics such as fundamentals of glassy dynamics and confinement effects. Based on the procedure presented in [P. Weigl et al., Z. Phys. Chem., 2018, 232, 1017-1039] in the present contribution two new TSD probes, namely indole and its derivative cbz-tryptophan, are identified and characterized in detail. In particular, their longer phosphorescence lifetime allows for a significant extension of the timescale of local mechanical and dipolar solvation measurements. In combination with previously used dyes a measurement window of up to five orders of magnitude in time can be covered. Furthermore, we show that in cbz-tryptophan the indole unit is the phosphorescence center, while the rest of the molecule only slightly contributes to the solvation response function. The detailed understanding of these two new TSD probes presented in this work, will allow in depth investigations of solvation and the corresponding dynamics also for biologically relevant systems in the future.