A new method for studying the vibration of non-homogeneous membranes

We present a method to solve the Helmholtz equation for a non-homogeneous membrane with Dirichlet boundary conditions at the border of arbitrary two-dimensional domains. The method uses a collocation approach based on a set of localized functions, called "little sinc functions", which are used to discretize two-dimensional regions. We have performed extensive numerical tests and we have compared the results obtained with the present method with the ones available from the literature. Our results show that the present method is very accurate and that its implementation for general problems is straightforward.Comment: 16 pages, 7 figures, 6 table

Experiencing EVA Park, A Multi-User Virtual World For People With Aphasia

Virtual worlds are used in wide-ranging ways by many people with long-term health conditions but their use by people with aphasia (PWA) has been limited. In contrast, this paper reports the use of EVA Park, a multi-user virtual world designed for PWA to practice conversations, focusing on people's emotional, social, and conversational experiences. An analysis of observation and interview data collected from 20 people with aphasia who participated in a 5 week therapy intervention revealed key themes related to user experience. The themes offer a rich insight into aspects of the virtual world experience for PWA that go beyond therapeutic outcomes. They are: affect (positive and negative), types of conversation, miscommunication and misunderstanding, immersion in the virtual world, social presence and initiative and flow. Overall, the study showed that participants experienced positive emotional and social outcomes. We argue that this was achieved as a consequence of EVA Park being not only accessible but also a varied and entertaining environment within which PWA experienced both the realistic and the quirky whilst engaging with others and having fun

Scaling relations of metallicity, stellar mass, and star formation rate in metal-poor starbursts: II. Theoretical models

Scaling relations of metallicity (O/H), star formation rate (SFR), and stellar mass give important insight on galaxy evolution. They are obeyed by most galaxies in the Local Universe and also at high redshift. In a companion paper, we compiled a sample of ~1100 galaxies from redshift 0 to ~3, spanning almost two orders of magnitude in metal abundance, a factor of $\sim10^6$ in SFR, and of ~10^5 in stellar mass. We have characterized empirically the star-formation "main sequence" (SFMS) and the mass-metallicity relation (MZR) for this sample, and also identified a class of low-metallicity starbursts, rare locally but more common in the distant universe. These galaxies deviate significantly from the main scaling relations, with high SFR and low metal content for a given M*. In this paper, we model the scaling relations and explain these deviations from them with a set of multi-phase chemical evolution models based on the idea that, independently of redshift, initial physical conditions in a galaxy's evolutionary history can dictate its location in the scaling relations. Our models are able to successfully reproduce the O/H, M*, and SFR scaling relations up to z~3, and also successfully predict the molecular cloud fraction as a function of stellar mass. These results suggest that the scaling relations are defined by different modes of star formation: an "active" starburst mode, more common at high redshift, and a quiescent "passive" mode that is predominant locally and governs the main trends.Comment: 17 pages, 7 figures, accepted for publication by MNRA

Image processing using Android device - gas-meter value recognition

Diplomová práce se zabývá návrhem zpracování obrazu v systému Android. Volbou vývojového prostředí a jeho implementací. Pracovní postup řešení problematiky zahrnuje vytvoření aplikace a grafického uživatelského rozhraní. Text zahrnuje popis funkcionality aplikace, komunikace s fotoaparátem, uložení a načítání dat. Dále popisuje použité algoritmy a metody zpracování obrazu pro detekci hodnot plynoměru.This thesis describes the design of the image processing for Android system, consisting of the choice of the development environment and its implementation. Workflow solution to the problem involves development of the Androidapplication and it’s graphical user interface. The text includes description of the application functionality, communicationwith a camera, storing and retrieving data. It also describes used algorithms and image processing methods used for detecting values from the counter of the gas meter.

Loss of Catalytically Inactive Lipid Phosphatase Myotubularin-related Protein 12 Impairs Myotubularin Stability and Promotes Centronuclear Myopathy in Zebrafish

X-linked myotubular myopathy (XLMTM) is a congenital disorder caused by mutations of the myotubularin gene, MTM1. Myotubularin belongs to a large family of conserved lipid phosphatases that include both catalytically active and inactive myotubularin-related proteins (i.e., “MTMRs”). Biochemically, catalytically inactive MTMRs have been shown to form heteroligomers with active members within the myotubularin family through protein-protein interactions. However, the pathophysiological significance of catalytically inactive MTMRs remains unknown in muscle. By in vitro as well as in vivo studies, we have identified that catalytically inactive myotubularin-related protein 12 (MTMR12) binds to myotubularin in skeletal muscle. Knockdown of the mtmr12 gene in zebrafish resulted in skeletal muscle defects and impaired motor function. Analysis of mtmr12 morphant fish showed pathological changes with central nucleation, disorganized Triads, myofiber hypotrophy and whorled membrane structures similar to those seen in X-linked myotubular myopathy. Biochemical studies showed that deficiency of MTMR12 results in reduced levels of myotubularin protein in zebrafish and mammalian C2C12 cells. Loss of myotubularin also resulted in reduction of MTMR12 protein in C2C12 cells, mice and humans. Moreover, XLMTM mutations within the myotubularin interaction domain disrupted binding to MTMR12 in cell culture. Analysis of human XLMTM patient myotubes showed that mutations that disrupt the interaction between myotubularin and MTMR12 proteins result in reduction of both myotubularin and MTMR12. These studies strongly support the concept that interactions between myotubularin and MTMR12 are required for the stability of their functional protein complex in normal skeletal muscles. This work highlights an important physiological function of catalytically inactive phosphatases in the pathophysiology of myotubular myopathy and suggests a novel therapeutic approach through identification of drugs that could stabilize the myotubularin-MTMR12 complex and hence ameliorate this disorder

Mutations in FRMD7, a newly identified member of the FERM family, cause X-linked idiopathic congenital nystagmus.

Idiopathic congenital nystagmus is characterized by involuntary, periodic, predominantly horizontal oscillations of both eyes. We identified 22 mutations in FRMD7 in 26 families with X-linked idiopathic congenital nystagmus. Screening of 42 singleton cases of idiopathic congenital nystagmus (28 male, 14 females) yielded three mutations (7%). We found restricted expression of FRMD7 in human embryonic brain and developing neural retina, suggesting a specific role in the control of eye movement and gaze stability

Orangutans (Pongo pygmaeus) do not Form Expectations Based on Their Partner’s Outcomes

Several primate species form expectations based on other’s outcomes. These individuals respond negatively when their outcomes differ from their partners’. The function and evolutionary pathway of this behavior are unknown, in part because all of the species which have thus far shown the response have similar life history patterns. In particular, all share traits related to a gregarious lifestyle, intelligence, and cooperativeness. The goal of the current paper was to test whether inequity is a homology among primates or a convergence based on some other characteristic by comparing one species known to show social comparisons, the chimpanzee, to another great ape which differs on several of these life history characteristics. Using a protocol identical to one used previously with chimpanzees, we tested whether orangutans, an intelligent but predominantly solitary species with few opportunities to cooperate, responded similarly. To allow for a strong comparison with chimpanzees (and other species), we used socially housed adults of both sexes, tested with members of their social group. We find that orangutans do not respond negatively to inequity, supporting previous findings and indicating that inequity responses in apes are likely a convergence based on either sociality or cooperative tendency. These results in such closely related species highlight the need for additional comparative studies to better understand the function and evolution of social behaviors

Vegetation and Invertebrate Community Response to Eastern Hemlock Decline in Southern New England

The introduction of Adelges tsugae (Hemlock Woolly Adelgid [HWA]) to the eastern United States has had a devastating impact on Tsuga canadensis (Eastern Hemlock). Although much research has been done to assess HWA impacts on ecosystem processes and vegetation structure, few researchers have examined community-level changes in highly infested forest stands. Here we assess the impact of Eastern Hemlock mortality on vegetation and invertebrate diversity and community structure by comparing low-impact (healthy) stands and stands heavily impacted by HWA. We sampled the vegetative and invertebrate diversity of 8 sites (4 low impact and 4 high impact) in the summer and fall of 2008. We found a shift in the understory plant community and the canopy and subcanopy arthropod communities. Herbaceous plant species richness was significantly higher at high-impact sites, with Betula lenta (Black Birch) being the most common woody species. Overall, forest invertebrate community diversity (measured using the Shannon-Weaver diversity index) was greater in high- versus low-impact sites. Of the 21 indicator species significantly associated with a given forest type, 14 and 7 species were associated with high- and low-impact forests, respectively. Variation in arthropod community structure was driven by above-ground differences; ground-level arthropod community composition did not differ between high- and low-impact sites. These results demonstrate some of the biodiversity impacts that can result from the invasion of an exotic insect into forested systems