From Caenorhabditis elegans to the Human Connectome: A Specific Modular Organisation Increases Metabolic, Functional, and Developmental Efficiency

The connectome, or the entire connectivity of a neural system represented by network, ranges various scales from synaptic connections between individual neurons to fibre tract connections between brain regions. Although the modularity they commonly show has been extensively studied, it is unclear whether connection specificity of such networks can already be fully explained by the modularity alone. To answer this question, we study two networks, the neuronal network of C. elegans and the fibre tract network of human brains yielded through diffusion spectrum imaging (DSI). We compare them to their respective benchmark networks with varying modularities, which are generated by link swapping to have desired modularity values but otherwise maximally random. We find several network properties that are specific to the neural networks and cannot be fully explained by the modularity alone. First, the clustering coefficient and the characteristic path length of C. elegans and human connectomes are both higher than those of the benchmark networks with similar modularity. High clustering coefficient indicates efficient local information distribution and high characteristic path length suggests reduced global integration. Second, the total wiring length is smaller than for the alternative configurations with similar modularity. This is due to lower dispersion of connections, which means each neuron in C. elegans connectome or each region of interest (ROI) in human connectome reaches fewer ganglia or cortical areas, respectively. Third, both neural networks show lower algorithmic entropy compared to the alternative arrangements. This implies that fewer rules are needed to encode for the organisation of neural systems

Quantum Twist to Complementarity: A Duality Relation

Some recent works have introduced a quantum twist to the concept of complementarity, exemplified by a setup in which the which-way detector is in a superposition of being present and absent. It has been argued that such experiments allow measurement of particle-like and wave-like behavior at the same time. Here we derive an inequality which puts a bound on the visibility of interference and the amount of which-way information that one can obtain, in the context of such modified experiments. As the wave-aspect can only be revealed by an ensemble of detections, we argue that in such experiments, a single detection can contribute only to one subensemble, corresponding to either wave-aspect or particle aspect. This way, each detected particle behaves either as particle or as wave, never both, and Bohr's complementarity is fully respected.Comment: Final version, to appear as letter in Prog. Theor. Exp. Phy

Two and Three Nucleon Forces

Chiral symmetry allows two and three nucleon forces to be treated in a single theoretical framework. We discuss two new features of this research programme at \cO(q^4) and the consistency of the overall chiral picture.Comment: Talk at the 18th International IUPAP Conference on Few-Body Problems in Physics, Santos, Brazi

Interpretation of Korean null pronouns in subject and object position: Comparing native and non-native speakers

We report an experiment that investigates how native and non-native Korean speakers’ interpretation of null pronouns in subject and object position is influenced by structural and discourse-level factors. We compare native Korean speakers to L2 Korean learners whose L1, Spanish, only has null pronouns in subject position. We find that native Korean speakers’ interpretation of subject and object null pronouns is guided by structural factors as well as discourse-level coherence relations, with subject nulls being more sensitive to coherence relations than object nulls. In contrast, our results suggest that L2 speakers’ interpretation of null pronouns in Korean is less influenced by coherence relations. Our results support claims that interface phenomena are challenging in L2 acquisition and provide new evidence that this occurs with null pronouns in L2 even when the L1 has null pronouns

Wiring cost in the organization of a biological network

To find out the role of the wiring cost in the organization of the neural network of the nematode \textit{Caenorhapditis elegans} (\textit{C. elegans}), we build the neuronal map of \textit{C. elegans} based on geometrical positions of neurons and define the cost as inter-neuronal Euclidean distance \textit{d}. We show that the wiring probability decays exponentially as a function of \textit{d}. Using the edge exchanging method and the component placement optimization scheme, we show that positions of neurons are not randomly distributed but organized to reduce the total wiring cost. Furthermore, we numerically study the trade-off between the wiring cost and the performance of the Hopfield model on the neural network

Courtship entanglements: a first report of mating behavior and sexual dichromatism in the Southeast Asian keel-bellied whipsnake, Dryophiops rubescens

We describe the first observations of courtship behavior and sexual dichromatism in the keel-bellied whipsnake, Dryophiops rubescens, from an encounter near Sandakan, eastern Sabah, Borneo, Malaysia. During this behavior, two males and a female were longitudinally intertwined, with the males jockeying for position along the body of the female. This “mating braid” lasted for well over 1 h, with the entwined snakes moving a distance of over 10 m together. While polygynous mating is known from other snake species, direct observations of mating behaviors in Southeast Asian colubrids are extremely rare. These observations also revealed the presence of sexual dichromatism in D. rubescens, with darker head coloration present in the males

Structural Disorder as Control of Transport Properties in Metallic Alloys

Structural disorder is ubiquitous for a large class of metallic alloys. Such an alloy’s transport properties are highly susceptible to change when the disorder is modified. A first-principle method has been developed for modeling of disorders in metallic alloys. In this approach, an alloy specimen is regarded as a randomly close-packed mixture of a population of nanocrystallites and constituent atoms in glassy state. The disorder is then represented by the size distribution function of the nanocrystallites. Under sustained exposure to thermal, stress, nuclear or chemical forcing at an elevated temperature, the distribution function becomes modified, and this process is predictable for a given forcing condition, and thus controllable. Transport of excitations is affected by the detail of the distribution function, making it possible to control transport properties, all at a fixed alloy composition. The modeling and experimental support will be presented

Update on pion weak decay constants in nuclear matter

The QCD sum rule calculation of the in-medium pion decay constants using pseudoscalar-axial vector correlation function, $i \int d^4x e^{ip\cdot x} < \rho| T[{\bar d}(x) i \gamma_5 u (x) {\bar u}(0) \gamma_\mu \gamma_5 d (0)] | \rho>$ is revisited. In particular, we argue that the dimension 5 condensate, $_N + {1\over 8} < {\bar q} g_s \sigma \cdot {\cal G} q >_N$, which is crucial for splitting the time ($f_t$) and space ($f_s$) components of the decay constant, is not necessarily restricted to be positive. Its positive value is found to yield a tachyonic pion mass. Using the in-medium pion mass as an input, we fix the dimension 5 condensate to be around $-0.025 {\rm GeV}^2 \sim -0.019$ GeV$^2$. The role of the $N$ and $\Delta$ intermediate states in the correlation function is also investigated. The $N$ intermediate state is found not to contribute to the sum rules. For the $\Delta$ intermediate state, we either treat it as a part of the continuum or propose a way to subtract explicitly from the sum rules. With (and without) explicit $\Delta$ subtraction while allowing the in-medium pion mass to vary within 139 MeV $\le m_\pi^* \le$ 159 MeV, we obtain $f_s/f_\pi = 0.37 \sim 0.78$ and $f_t / f_\pi = 0.63 \sim 0.79$.Comment: 18 pages including 5 postscript figure