The social affordances of flashpacking: exploring the mobility nexus of travel and communication

The proliferation of digital devices and online social media and networking technologies has altered the backpacking landscape in recent years. Thanks to the ready availability of online communication, travelers are now able to stay in continuous touch with friends, family and other travelers while on the move. This article introduces the practice of ‘flashpacking’ to describe this emerging trend and interrogates the patterns of connection and disconnection that become possible as corporeal travel and social technologies converge. Drawing on the concepts of ‘assemblages’ and ‘affordances’, we outline several aspects of this new sociality: virtual mooring, following, collaborating, and (dis)connecting. The conclusion situates this discussion alongside broader questions about the shifting nature of social life in an increasingly mobile and mediated world and suggests directions for future research at the intersection of tourism and technology

Proton-electron mass ratio from HD+^+ revisited

We present a new derivation of the proton-electron mass ratio from the hydrogen molecular ion, HD$^+$. The derivation entails the adjustment of the mass ratio in highly precise theory so as to reproduce accurately measured ro-vibrational frequencies. This work is motivated by recent improvements of the theory, as well as the more accurate value of the electron mass in the recently published CODATA-14 set of fundamental constants, which justifies using it as input data in the adjustment, rather than the proton mass value as done in previous works. This leads to significantly different sensitivity coefficients and, consequently, a different value and larger uncertainty margin of the proton-electron mass ratio as obtained from HD$^+$

Molecular Dynamics Simulations of Detonation Instability

After making modifications to the Reactive Empirical Bond Order potential for Molecular Dynamics (MD) of Brenner et al. in order to make the model behave in a more conventional manner, we discover that the new model exhibits detonation instability, a first for MD. The instability is analyzed in terms of the accepted theory.Comment: 7 pages, 6 figures. Submitted to Phys. Rev. E Minor edits. Removed parenthetical statement about P^\nu from conclusion

Investigating microstructural variation in the human hippocampus using non-negative matrix factorization

In this work we use non-negative matrix factorization to identify patterns of microstructural variance in the human hippocampus. We utilize high-resolution structural and diffusion magnetic resonance imaging data from the Human Connectome Project to query hippocampus microstructure on a multivariate, voxelwise basis. Application of non-negative matrix factorization identifies spatial components (clusters of voxels sharing similar covariance patterns), as well as subject weightings (individual variance across hippocampus microstructure). By assessing the stability of spatial components as well as the accuracy of factorization, we identified 4 distinct microstructural components. Furthermore, we quantified the benefit of using multiple microstructural metrics by demonstrating that using three microstructural metrics (T1-weighted/T2-weighted signal, mean diffusivity and fractional anisotropy) produced more stable spatial components than when assessing metrics individually. Finally, we related individual subject weightings to demographic and behavioural measures using a partial least squares analysis. Through this approach we identified interpretable relationships between hippocampus microstructure and demographic and behavioural measures. Taken together, our work suggests non-negative matrix factorization as a spatially specific analytical approach for neuroimaging studies and advocates for the use of multiple metrics for data-driven component analyses

Folding and Base Pairing of a Fibrinogen Specific DNA Aptamer

Abstract Nucleic acid aptamers can be directed to bind to a variety of target molecules that range widely in molecular size. Their high specificity and selectivity for their targets, in addition to the relative ease in generating aptamers, have sparked their development as drugs and use in diagnostic applications. The 90-mer DNA aptamer (Ap90), specific for the glycoprotein fibrinogen was analyzed by a combination of gel electrophoresis, secondary structure prediction software and NMR spectroscopy to determine what structural motifs are formed prior to binding to its target. Native gel electrophoresis and structure prediction indicate that the aptamer is partially folded. This was further supported by the NMR studies focusing on base pairing. The NMR experiments revealed that the aptamer only forms a maximum of 4-5 AT and 6-8 GC base pairs. Using several model substrates, the base paired region was identified as a hairpin structure originating from the primer region. Changing the solvent conditions did not elicit additional base pairs or promote stable tertiary structures. These results demonstrate that the majority of the aptamer has no established structure prior to binding and guides the design of more efficient aptamers

A Spectral Analysis of the Massalia Asteroid Family to Evaluate the L-Chondrite Source Hypothesis

A major research objective within asteroid science is to identify the source bodies of the meteorites. So far, possible or probable parent bodies have only been identified for a few meteorite types. These meteorite types include the H-type ordinary chon-drites [1,2], HEDs [3,4], pallasites [3], and mesosider-ites [5]. Identifying the parent bodies of meteorites helps to determine the location within the solar nebula where the geochemical processes, recorded in meteorites, took place. This has significantly increased our understanding of the evolution of the solar nebula and the early so-lar system [6]. Among the many meteorite types whose parent bodies are unknown are the L-chondrites. L-chondrites exhibit evidence of a shock event that occurred around 470 Ma, which implies that the L-chondrites resulted from an impact event which may have disrupted the L-chondrite parent body. This evidence is corroborated by fossil L-chondrite meteorites found in Ordovician sedimentary rocks dating to the same time period [7-12]. This suggests that if the source outcrop of the L-chondrites stills exists today, it is within an asteroid family. The Massalia asteroid family has been suggested to be a possible source of the L-chondrites [13]. We are currently testing this hypothesis. So far, we have observed fourteen Massalia family asteroids, analyzed their spectra, and interpreted their spectra to determine their meteorite analogues in an effort to see whether or not the analogues support our hypothesis. This abstract reports the initial results for seven of these bodies

A reduced model for shock and detonation waves. II. The reactive case

We present a mesoscopic model for reactive shock waves, which extends a previous model proposed in [G. Stoltz, Europhys. Lett. 76 (2006), 849]. A complex molecule (or a group of molecules) is replaced by a single mesoparticle, evolving according to some Dissipative Particle Dynamics. Chemical reactions can be handled in a mean way by considering an additional variable per particle describing a rate of reaction. The evolution of this rate is governed by the kinetics of a reversible exothermic reaction. Numerical results give profiles in qualitative agreement with all-atom studies