Embeddings of finite groups in Bn/Γk(Pn)B_n/\Gamma_k(P_n) for k=2,3k=2, 3

Let $n \geq 3$. In this paper, we study the problem of whether a given finite group $G$ embeds in a quotient of the form $B_n/\Gamma_k(P_n)$, where $B_n$ is the $n$-string Artin braid group, $k \in \{2, 3\}$, and $\{\Gamma_l(P_n)\}_{l\in \mathbb{N}}$ is the lower central series of the $n$-string pure braid group $P_n$. Previous results show that a necessary condition for such an embedding to exist is that $|G|$ is odd (resp. is relatively prime with $6$) if $k=2$ (resp. $k=3$), where $|G|$ denotes the order of $G$. We show that any finite group $G$ of odd order (resp. of order relatively prime with $6$) embeds in $B_{|G|}/\Gamma_2(P_{|G|})$ (resp. in $B_{|G|}/\Gamma_3(P_{|G|})$). The result in the case of $B_{|G|}/\Gamma_2(P_{|G|})$ has been proved independently by Beck and Marin. One may then ask whether $G$ embeds in a quotient of the form $B_n/\Gamma_k(P_n)$, where $n < |G|$ and $k \in \{2, 3\}$. If $G$ is of the form $\mathbb{Z}_{p^r} \rtimes_{\theta} \mathbb{Z}_d$, where the action $\theta$ is injective, $p$ is an odd prime (resp. $p \geq 5$ is prime) $d$ is odd (resp. $d$ is relatively prime with $6$) and divides $p-1$, we show that $G$ embeds in $B_{p^r}/\Gamma_2(P_{p^r})$ (resp. in $B_{p^r}/\Gamma_3(P_{p^r})$). In the case $k=2$, this extends a result of Marin concerning the embedding of the Frobenius groups in $B_n/\Gamma_2(P_n)$, and is a special case of another result of Beck and Marin. Finally, we construct an explicit embedding in $B_9/\Gamma_2(P_9)$ of the two non-Abelian groups of order $27$, namely the semi-direct product $\mathbb{Z}_9 \rtimes \mathbb{Z}_3$, where the action is given by multiplication by $4$, and the Heisenberg group mod $3$

Performance of MV distributed energy power systems under model-predictive control and conventional power systems state estimators

© 20xx IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works.In this paper, the performance of a middle voltage (MV) distributed power generation system under a Model Predictive Control (MPC) strategy is tested. The designed controller receives process information from an state estimation unit, composed of a Weighted Least-Squares strategy (WLS). The contribution is focused on performing the frequency and voltage regulation of the system, considering moreover the dynamic behavior of storage units and capacitors, and feeding back information to the control system considering the transmission delay. The results show that the closed loop based on the proposed strategy achieves the required performance and can be useful to be applied to more complex systems such as low-voltage (LV) generation systems.Peer ReviewedPostprint (author's final draft

Rediscovery of Passiflora danielii Killip, 1960 (subgenus Passiflora): a threatened narrow endemic species of Colombia

Passiflora danielii, an endemic species to Colombia, which is threatened, was rediscovered in the Department of Antioquia, where it has not been reported since 1938. The species was only known from the type locality (Municipality of Cocorná). Now, four new locations are added near it. The current study further presents a revised morphological description of P. danielii based on fresh material, along with an updated distribution map. Finally, following the IUCN Red List Criteria, P. danielii was classified as Critically Endangered (CR) species

Almost-crystallographic groups as quotients of Artin braid groups

Let $n, k \geq 3$. In this paper, we analyse the quotient group $B\_n/\Gamma\_k(P\_n)$ of the Artin braid group $B\_n$ by the subgroup $\Gamma\_k(P\_n)$ belonging to the lower central series of the Artin pure braid group $P\_n$. We prove that it is an almost-crystallographic group. We then focus more specifically on the case $k=3$. If $n \geq 5$, and if $\tau \in N$ is such that $gcd(\tau, 6) = 1$, we show that $B\_n/\Gamma\_3 (P\_n)$ possesses torsion $\tau$ if and only if $S\_n$ does, and we prove that there is a one-to-one correspondence between the conjugacy classes of elements of order $\tau$ in $B\_n/\Gamma\_3 (P\_n)$ with those of elements of order $\tau$ in the symmetric group $S\_n$. We also exhibit a presentation for the almost-crystallographic group $B\_n/\Gamma\_3 (P\_n)$. Finally, we obtain some $4$-dimensional almost-Bieberbach subgroups of $B\_3/\Gamma\_3 (P\_3)$, we explain how to obtain almost-Bieberbach subgroups of $B\_4/\Gamma\_3(P\_4)$ and $B\_3/\Gamma\_4(P\_3)$, and we exhibit explicit elements of order $5$ in $B\_5/\Gamma\_3 (P\_5)$

Using search queries for malaria surveillance, Thailand

Background: Internet search query trends have been shown to correlate with incidence trends for select infectious diseases and countries. Herein, the first use of Google search queries for malaria surveillance is investigated. The research focuses on Thailand where real-time malaria surveillance is crucial as malaria is re-emerging and developing resistance to pharmaceuticals in the region. Methods: Official Thai malaria case data was acquired from the World Health Organization (WHO) from 2005 to 2009. Using Google correlate, an openly available online tool, and by surveying Thai physicians, search queries potentially related to malaria prevalence were identified. Four linear regression models were built from different sub-sets of malaria-related queries to be used in future predictions. The models’ accuracies were evaluated by their ability to predict the malaria outbreak in 2009, their correlation with the entire available malaria case data, and by Akaike information criterion (AIC). Results: Each model captured the bulk of the variability in officially reported malaria incidence. Correlation in the validation set ranged from 0.75 to 0.92 and AIC values ranged from 808 to 586 for the models. While models using malaria-related and general health terms were successful, one model using only microscopy-related terms obtained equally high correlations to malaria case data trends. The model built strictly of queries provided by Thai physicians was the only one that consistently captured the well-documented second seasonal malaria peak in Thailand. Conclusions: Models built from Google search queries were able to adequately estimate malaria activity trends in Thailand, from 2005–2010, according to official malaria case counts reported by WHO. While presenting their own limitations, these search queries may be valid real-time indicators of malaria incidence in the population, as correlations were on par with those of related studies for other infectious diseases. Additionally, this methodology provides a cost-effective description of malaria prevalence that can act as a complement to traditional public health surveillance. This and future studies will continue to identify ways to leverage web-based data to improve public health

Estudio del costo y principales causas del ausentismo laboral en las empresas afiliadas a la ANDI seccional Risaralda – Quindío

La investigación llevada a cabo en este trabajo, con la cual se determino el costo aproximado del ausentismo laboral y las principales causas que lo generan, supero en el 2.008, los 2.300 millones de pesos; y en el 2.009, la tendencia es que aumente en más de un 20%. La participación de las empresas afiliadas a la ANDI, en esta primera investigación es muy positiva, ya que se conto con un alto compromiso por los integrantes del comité de salud ocupacional; que permitió obtener los resultados de alto impacto, que generaron compromisos de parte de la alta Gerencia de cada empresa que participó del estudio, y además la Junta Directiva de la ANDI, se comprometió con el comité de Salud Ocupacional, para proporcionar todas las herramientas necesarias que busquen la reducción de ausentismo laboral, que a la larga se verá reflejado en un mejoramiento en productividad y optimización de costos y gastos generados por el ausentismo laboral. Por tal, motivo se aprobó que este estudio se haga por trimestre ó semestralmente desde el 2.010, y que del análisis de los resultados obtenidos, se planten programas, capacitaciones teóricas y técnicas, que tengan como objetivo general, el de generar valor, comprometiendo a los trabajadores, empleadores y empresas, para reducir costos por ausentismo. La invitación para el 2.010, es que se unan más empresas a este estudio, lo cual sirva cada vez más, para tener una visión de las empresas ubicadas en el Departamento de Risaralda y Quindío, que refleje la realidad del costo y las causas que se generan por la ausencia de trabajadores