Local Leaders in Random Networks

We consider local leaders in random uncorrelated networks, i.e. nodes whose degree is higher or equal than the degree of all of their neighbors. An analytical expression is found for the probability of a node of degree $k$ to be a local leader. This quantity is shown to exhibit a transition from a situation where high degree nodes are local leaders to a situation where they are not when the tail of the degree distribution behaves like the power-law $\sim k^{-\gamma_c}$ with $\gamma_c=3$. Theoretical results are verified by computer simulations and the importance of finite-size effects is discussed.Comment: 4 pages, 2 figure

Visie van de Boergergroep

De BoergerGroep is een netwerk van burgers die met hart en ziel mee willen denken en mee willen praten over het platteland en hoe dat er in de toekomst uit kan zien. Zij hebben daarvoor met elkaar een visie opgesteld, die we hier gepresenteerd wordt. De BoergerGroep wil meedenken over de relatie tussen stad en platteland en welke kant het met de landbouw op moet

Defective complex I assembly due to C20orf7 mutations as a new cause of Leigh syndrome

Background: Leigh syndrome is an early onset, progressive, neurodegenerative disorder with developmental and motor skills regression. Characteristic magnetic resonance imaging abnormalities consist of focal bilateral lesions in the basal ganglia and/or the brainstem. The main cause is a deficiency in oxidative phosphorylation due to mutations in an mtDNA or nuclear oxidative phosphorylation gene. Methods and results: A consanguineous Moroccan family with Leigh syndrome comprise 11 children, three of which are affected. Marker analysis revealed a homozygous region of 11.5 Mb on chromosome 20, containing 111 genes. Eight possible mitochondrial candidate genes were sequenced. Patients were homozygous for an unclassified variant (p.P193L) in the cardiolipin synthase gene (CRLS1). As this variant was present in 20% of a Moroccan control population and enzyme activity was only reduced to 50%, this could not explain the rare clinical phenotype in our family. Patients were also homozygous for an amino acid substitution (p.L159F) in C20orf7, a new complex I assembly factor. Parents were heterozygous and unaffected sibs heterozygous or homozygous wild type. The mutation affects the predicted S-adenosylmethionine (SAM) dependent methyltransferase domain of C20orf7, possibly involved in methylation of NDUFB3 during the assembly process. Blue native gel electrophoresis showed an altered complex I assembly with only 30-40% of mature complex I present in patients and 70-90% in carriers. Conclusions: A new cause of Leigh syndrome can be a defect in early complex I assembly due to C20orf7 mutations

Численный анализ распространения и усиления волн цунами на северо-западном шельфе Черного моря

Выполнен численный анализ распространения длинных волн в северо-западной части Черного моря. Рассмотрено 10 возможных зон сейсмической генерации цунами. Расчеты выполнены на сетке с шагом 500 м. Показано, что положение очага цунами существенно влияет на распределение высот волн вдоль побережья. Как правило, наиболее интенсивные волны формируются у ближайшего участка берега. Землетрясения в Южнобережной сейсмической зоне не могут привести к цунамиопасности в западной части моря. Только сильные землетрясения в северо-западной части способны вызывать заметные колебания уровня Черного моря. Период цунами в районе Одессы составляет около 1 ч и зависит от магнитуды землетрясения, в районе Севастополя он в 2 – 3 раза меньше. В большинстве пунктов побережья экстремальные подъемы и понижения уровня моря не превышают по абсолютной величине начального смещения поверхности моря в очаге цунами. Для отдельных участков побережья Румынии и западного побережья Крыма наблюдается некоторое усиление волн, излученных из зон генерации, расположенных в более глубоководной части исследуемого района. С ростом магнитуды землетрясения усиление волн у берега становится более значительным.Виконаний чисельний аналіз розповсюдження довгих хвиль у північно-західній частині Чорного моря. Розглянуто 10 можливих зон сейсмічної генерації цунамі. Розрахунки виконані на сітці з кроком 500 м. Показано, що положення осередку цунамі суттєво впливає на розподіл висот хвиль уздовж побережжя. Як правило, найінтенсивніші хвилі формуються близько найближчої ділянки берега. Землетруси в південнобережній сейсмічній зоні не можуть призвести до цунамонебезпеки в західній частині моря. Лише сильні землетруси в північнозахідній частині здатні викликати помітні коливання рівня Чорного моря. Період цунамі в районі Одеси складає близько 1 години і залежить від магнітуди землетрусу, в районі Севастополя він в 2 – 3 рази менший. У більшості пунктів побережжя екстремальні підйоми і пониження рівня моря не перевищують за абсолютною величиною початкового зсуву поверхні моря в осередку цунамі. Для окремих ділянок побережжя Румунії і західного побережжя Криму спостерігається деяке посилення хвиль, які випромінюють із зон генерації, розташованих в більш глибоководній частині досліджуваного району. Із зростанням магнітуди землетрусу посилення хвиль біля берега стає значнішим.Numerical analysis of long wave propagation in the Black Sea northwestern part is carried out. Ten possible zones of tsunami seismic generation are considered. The calculation are performed on the grid with a step 500 m. It is shown that location of tsunami source effects essentially the distribution of waves’ heights along the coast. As a rule, the most intensive waves are formed in the part closest to the coast. Earthquakes in the South coast seismic zone can not result in tsunami threat in the western part of the sea. Only strong earthquakes in the Black Sea northwestern part can generate noticeable sea level oscillations. Tsunami period near Odessa is about one hour and it depends on the earthquake magnitude. In the Sevastopol region it is 2 – 3 times lower. In the majority of coastal points extreme rises and falls of the sea level do not exceed the absolute value of the initial sea surface elevation in the tsunami source. Some intensification of the waves generated in deeper regions of the area under study is possible in certain parts of the Romanian coast and the Crimean western coast. The wave intensification near the coast grows with the increase of the earthquake magnitude

Evolution of Linear Absorption and Nonlinear Optical Properties in V-Shaped Ruthenium(II)-Based Chromophores

In this article, we describe a series of complexes with electron-rich cis-{Ru^(II)(NH_3)_4}^(2+) centers coordinated to two pyridyl ligands bearing N-methyl/arylpyridinium electron-acceptor groups. These V-shaped dipolar species are new, extended members of a class of chromophores first reported by us (Coe, B. J. et al. J. Am. Chem. Soc. 2005, 127, 4845−4859). They have been isolated as their PF_6− salts and characterized by using various techniques including ^1H NMR and electronic absorption spectroscopies and cyclic voltammetry. Reversible Ru^(III/II) waves show that the new complexes are potentially redox-switchable chromophores. Single crystal X-ray structures have been obtained for four complex salts; three of these crystallize noncentrosymmetrically, but with the individual molecular dipoles aligned largely antiparallel. Very large molecular first hyperpolarizabilities β have been determined by using hyper-Rayleigh scattering (HRS) with an 800 nm laser and also via Stark (electroabsorption) spectroscopic studies on the intense, visible d → π^* metal-to-ligand charge-transfer (MLCT) and π → π^* intraligand charge-transfer (ILCT) bands. The latter measurements afford total nonresonant β_0 responses as high as ca. 600 × 10^(−30) esu. These pseudo-C_(2v) chromophores show two substantial components of the β tensor, β_(zzz) and β_(zyy), although the relative significance of these varies with the physical method applied. According to HRS, β_(zzz) dominates in all cases, whereas the Stark analyses indicate that β_(zyy) is dominant in the shorter chromophores, but β_(zzz) and β_(zyy) are similar for the extended species. In contrast, finite field calculations predict that β_(zyy) is always the major component. Time-dependent density functional theory calculations predict increasing ILCT character for the nominally MLCT transitions and accompanying blue-shifts of the visible absorptions, as the ligand π-systems are extended. Such unusual behavior has also been observed with related 1D complexes (Coe, B. J. et al. J. Am. Chem. Soc. 2004, 126, 3880−3891)

Assessment of animal African trypanosomiasis (AAT) vulnerability in cattle-owning communities of sub-Saharan Africa

Background: Animal African trypanosomiasis (AAT) is one of the biggest constraints to livestock production and a threat to food security in sub-Saharan Africa. In order to optimise the allocation of resources for AAT control, decision makers need to target geographic areas where control programmes are most likely to be successful and sustainable and select control methods that will maximise the benefits obtained from resources invested. Methods: The overall approach to classifying cattle-owning communities in terms of AAT vulnerability was based on the selection of key variables collected through field surveys in five sub-Saharan Africa countries followed by a formal Multiple Correspondence Analysis (MCA) to identify factors explaining the variations between areas. To categorise the communities in terms of AAT vulnerability profiles, Hierarchical Cluster Analysis (HCA) was performed. Results: Three clusters of community vulnerability profiles were identified based on farmers’ beliefs with respect to trypanosomiasis control within the five countries studied. Cluster 1 communities, mainly identified in Cameroon, reported constant AAT burden, had large trypanosensitive (average herd size = 57) communal grazing cattle herds. Livestock (cattle and small ruminants) were reportedly the primary source of income in the majority of these cattle-owning households (87.0 %). Cluster 2 communities identified mainly in Burkina Faso and Zambia, with some Ethiopian communities had moderate herd sizes (average = 16) and some trypanotolerant breeds (31.7 %) practicing communal grazing. In these communities there were some concerns regarding the development of trypanocide resistance. Crops were the primary income source while communities in this cluster incurred some financial losses due to diminished draft power. The third cluster contained mainly Ugandan and Ethiopian communities which were mixed farmers with smaller herd sizes (average = 8). The costs spent diagnosing and treating AAT were moderate here. Conclusions: Understanding how cattle-owners are affected by AAT and their efforts to manage the disease is critical to the design of suitable locally-adapted control programmes. It is expected that the results could inform priority setting and the development of tailored recommendations for AAT control strategies