A smart meter, a component of smart grid systems, has low computational capability. This is in contrast to data collection units (DCUs) and meter data management servers (MDMSs). In this study, we propose a lightweight signature scheme and an authentication and report protocol that can reduce computational overhead and facilitate efficient operation of these three components in smart grid systems. The proposed signature scheme, called the linear map digital signature scheme (LMDSS), uses properties of linear maps and matrix operations; hence, it has low computational requirements. The proposed protocol is a delegation-based authentication protocol that uses an intermediate node, DCU. Using the proposed protocol, authentication of a DCU can be completed by a hash function. To evaluate the performance of the scheme and protocol, we implemented signature schemes, ours and others, and simulated the proposed protocol to obtain analytical results. We also proved that the scheme is secure by using a random oracle and analyzing the security of the protocol based on possible attack scenarios.

We introduce a mathematical model to study the transport of ions through ion channels. The system is derived in the framework of the energetic variational approach, taking into account the coupling between electrostatics, diffusion, and protein (ion channel) structure. The geometric constraints of the ion channel are introduced through a potential energy controlling the local maximum volume inside the ion channel. A diffusive interface (labeling) deion is also employed to describe the geometric configuration of the channels. The surrounding bath and channel are smoothly connected with the antechamber region by this label function. A corresponding modified Poisson–Nernst–Planck channel system for ion channels is derived using the variational derivatives of the total energy functional. The functional consists of the entropic free energy for diffusion of the ions, the electrostatic potential energy, the repulsive potential energy for the excluded volume effect of the ion particles, and the potential energy for the geometric constraints of the ion channel. For the biological application of such a system, we consider channel recordings of voltage clamp to measure the current flowing through the ion channel. The results of one­dimensional numerical simulations are presented to demonstrate some signature effects of the channel, such as the current output produced by single­step and double­step voltage inputs. Copyright © 2013 John Wiley & Sons, Ltd.

Conclusion: The study showed that combined repetitive transcranial magnetic stimulation (rTMS) on the auditory cortex and prefrontal cortex has more benefit than rTMS on the auditory cortex alone for tinnitus control in patients with depression. Further studies for the most optimal combination of stimulation on both areas are needed. Objective: Recent studies suggest that the neuronal network changes of chronic tinnitus are beyond the auditory pathway. There is increasing evidences for the application of rTMS on multiple brain cortices in addition to the auditory cortex for the treatment of tinnitus. Sequential rTMS was performed on the auditory cortex alone as well as the auditory cortex combined with prefrontal cortex in patients with both chronic tinnitus and depression. Methods: Patients who presented with chronic tinnitus of more than 1 year were enrolled in the present study (seven males, four females; mean age 54 years). To select the site for the rTMS, PET CT was performed. Patients received the first rTMS on the primary auditory cortex for 5 days and on the primary auditory cortex and prefrontal cortex in the second application after tinnitus relapse. The Tinnitus Handicap Inventory (THI), visual analog scale (VAS), and Beck Depression Inventory (BDI) were evaluated before and after rTMS. Results: The mean THI score of the eight patients with depression changed from 77.5 ± 15 to 61.8 ± 20.1 after the second rTMS. There was statistical significance only for the second rTMS. The VAS score changed from 8.6 ± 1.6 to 6.3 ± 1.8 after the first rTMS and from 7.6 ± 2.4 to 4.6 ± 2.7 after the second rTMS, showing statistically significant changes both times. The THI changes after the second rTMS were greater than after the first rTMS, and the changes in VAS score showed a similar pattern. The changes in BDI score, which indicates the severity of depression, showed a variable pattern after rTMS. Patients with mild depression (10≤ BDI score <16, n = 4) showed significant improvement of THI with the second combined rTMS (ΔTHI = 24.5) as compared with the first rTMS on the auditory area (ΔTHI = 6). In contrast, combined rTMS did not show any better improvement on THI (ΔTHI = 6.5) than the first rTMS on the auditory cortex (ΔTHI = 7) in patients without depression (BDI <10, n = 3) and patients with moderate to severe depression (BDI ≥16, n = 4).

We propose the full information minority game (FIMG) in which agents perfectly recognize their impact on the market. For reflecting the impact of agents, we introduce an actual total action and an actual payoff which depend on the agent’s strategies. Unlike the perpetual fluctuating dynamics of the standard minority game, the dynamics of the FIMG settles into one of four steady states after a transient time. We classify steady states of the FIMG and analyze their characteristics. In most cases, the total payoff is maximized, and the total action settles into a periodic state. For measuring the degree of cooperation on the FIMG, we calculate a fraction of total payoff maximization and a mean relaxation time for the dynamics to settle into a steady state whose total payoff is maximized.

We consider the problem of reconstructing a wide sense stationary band-limited process from its local averages taken either at the Nyquist rate or above. As a result we obtain a sufficient condition under which average sampling expansions hold in mean square and for almost all sample functions. Truncation and aliasing errors of the expansion are also discussed.

Subterranean termites construct complex tunnel networks for foraging. During travel in the tunnels, termites often encounter one another when passing in opposite directions. Such encounters are likely to affect the “ment efficiency,” which is the time required for a termite to travel a certain distance in a tunnel. In this study, we explored how individual–individual encounters affect ment efficiency in tunnels by measuring the time (τ) taken by two termites to pass one another in tunnels of different curvatures. Artificial tunnels of 5 cm in length and variable widths (W) of 2, 3, or 4 mm were made. Tunnel distance (D) was 2, 3, 4, or 5 cm. When D had a higher value, curvature was lower. When W = 2, τ was significantly shorter in the tunnel with D = 5 than in tunnels of D = 2, 3, or 4, whereas τ was statistically the same for D = 2, 3 and 4. When W = 3, τ was shorter in the tunnel with D = 5 than for D = 3 and 4, while τ was longer in the tunnel with D = 2 than for D = 3 and 4. When W = 4, τ was longer in the tunnels with D = 2 and 3 than for D = 4 and 5. Based on these observations, 3 types of termite behavior were identified: biased walking, backward walking, and zigzag walking. We considered these results in relation to foraging efficiency.

Subterranean termites (Isoptera) build tunnel networks to obtain food resources and nesting space. When tunneling, termites encounter spatial heterogeneity, such as differing soil pore space and moisture levels. This heterogeneity creates 2 types of irregularities in the tunnel surface: (1) a bumpy tunnel-wall structure caused by variable soil texture; and (2) hollow space within the tunnel, where tunnels pass through soil pores. We previously explored the response of termites to bumpy tunnel structure. In the present study, we investigated termite behavior in response to differing volumes of soil pore space. This response behavior is closely related to ment efficiency. We designed 8-cm-long artificial tunnels with hollow spaces in a 2-dimensional arena. The hollow spaces were represented as circular holes with varying diameters D (2, 3, 4, 6, 8, or 10 mm), positioned at the center of the tunnel. Tunnel widths, W, were 2 and 3 mm. We systematically observed the ment of termites (Reticulitermes speratus kyushuensis Morimoto) at the hole, and measured the time required (τ) for termites to pass through the tunnels. Time τ was shorter for tunnels with holes between 2 and 6 mm diameter than for those with holes of 8 or 10 mm diameter, for tunnels of both widths. Time τ was significantly different between (W, D) = (2, 10) and (3, 10). These results were explained by 3 types of behaviors. The implications of these findings are briefly discussed in relation to termite foraging efficiency. Las termitas subterráneas construyen redes de túneles para obtener recursos alimentarios y espacio para sus nidos. Cuando hacen los túneles, las termitas se encuentran con la heterogeneidad espacial, como diferentes espacios de poros en el suelo y el nivel de humedad. Esta heterogeneidad crea 2 tipos de irregularidades en la superficie del túnel: (1) una estructura del túnel con baches en los paredes causada por la textura del suelo variable y (2) espacios huecos dentro del túnel, donde los túneles pasan a través de los poros del suelo. Anteriormente, se estudió la respuesta de las termitas a las estructuras de túneles llenos de baches. En el presente estudio, se investigó el comportamiento de las termitas en respuesta a diferentes volúmenes de espacio de los poros del suelo. Este comportamiento de respuesta está estrechamente relacionado con la eficiencia del movimiento. Hemos diseñado túneles artificiales de 8 cm de largo con espacios huecos en una arena de 2 dimensiones. Los espacios huecos se representan como agujeros circulares con el diámetro D (2, 3, 4, 6, 8, o 10 mm), puestos en el centro del túnel. La anchura de túnel, W, fue de 2 y 3 mm. Se observó sistemáticamente el movimiento de las termitas (Reticulitermes speratus kyushuensis Morimoto; Rhinotermitidae) en las aperaturas, y se midió el tiempo requerido (τ) para que las termitas pasaran a través de los túneles. El tiempo, τ, fue más corto en los túneles con aperaturas entre 2 y 6 mm de diámetro que para los que tienen aperaturas de 8 o 10 mm de diámetro, para los túneles de ambos anchos. El tiempo, τ, fue significativamente diferente entre (W, D) = (2, 10) y (3, 10). Estos resultados son explicados por 3 clases de comportamiento. Se discuten brevemente las implicaciones de estos hallazgos en relación con la eficiencia de forrajeo de las termitas.

Flocking may be an advantageous strategy for acquiring food resources. The degree of advantage is related to two factors: the ability of flock members to detect food resources and patterns of food distribution in the environment. To understand foraging efficiency as a function of these factors, I constructed a two-dimensional (2D) flocking model incorporating the two factors. At the start of the simulation, food particles were heterogeneously distributed. The heterogeneity, H, was characterized as a value ranging from 0.0 to 1.0. For each flock member, food sensing ability was defined by two variables: sensing distance, R and sensing angle, θ. Foraging efficiency of a flock was defined as the time, τ, required for a flock to consume all the available food resources. Simulation results showed that flock foraging is most efficient when individuals had an intermediate sensing ability (R = 60), but decreased for low (R < 60) and high (R > 60) sensing ability. When R > 60, patterns in foraging efficiency with increasing sensing distance and food resource aggregation were less consistent. This inconsistency was due to instability of the flock and a higher rate of individuals failing to capture target food resources. In addition, I briefly discuss the benefits obtained by foraging in flocks from an evolutionary perspective.