Upconversion cooling of Er-doped low-phonon fluorescent solids

We report on a novel mechanism for laser cooling of fluorescent solids based on infrared-to-visible upconversion often found in rare-earth-doped low-phonon materials. This type of optical cooling presents some advantages with regards to conventional anti-Stokes cooling. Among them, it allows to obtain cooling in a broader range of frequencies around the barycenter of the infrared emitting band.Comment: 4 pages, 1 figur

A Qualitative Analysis of the Persuasive Properties of Argumentation Schemes

Argumentation schemes are generalised patterns that provide a way to (partially) dissociate the content from the reasoning structure of the argument. On the other hand, Cialdini’s principles of persuasion provide a generic model to analyse the persuasive properties of human interaction (e.g., natural language). Establishing the relationship between principles of persuasion and argumentation schemes can contribute to the improvement of the argument-based human-computer interaction paradigm. In this work, we perform a qualitative analysis of the persuasive properties of argumentation schemes. For that purpose, we present a new study conducted on a population of over one hundred participants, where twelve different argumentation schemes are instanced into four different topics of discussion considering both stances (i.e., in favour and against). Participants are asked to relate these argumentation schemes with the perceived Cialdini’s principles of persuasion. From the results of our study, it is possible to conclude that some of the most commonly used patterns of reasoning in human communication have an underlying persuasive focus, regardless of how they are instanced in natural language argumentation (i.e., their stance, the domain, or their content)

A Qualitative Analysis of the Persuasive Properties of Argumentation Schemes

Argumentation schemes are generalised patterns that provide a way to (partially) dissociate the content from the reasoning structure of the argument. On the other hand, Cialdini’s principles of persuasion provide a generic model to analyse the persuasive properties of human interaction (e.g., natural language). Establishing the relationship between principles of persuasion and argumentation schemes can contribute to the improvement of the argument-based human-computer interaction paradigm. In this work, we perform a qualitative analysis of the persuasive properties of argumentation schemes. For that purpose, we present a new study conducted on a population of over one hundred participants, where twelve different argumentation schemes are instanced into four different topics of discussion considering both stances (i.e., in favour and against). Participants are asked to relate these argumentation schemes with the perceived Cialdini’s principles of persuasion. From the results of our study, it is possible to conclude that some of the most commonly used patterns of reasoning in human communication have an underlying persuasive focus, regardless of how they are instanced in natural language argumentation (i.e., their stance, the domain, or their content)

A new analytic model for the cognitive radio jump-stay algorithm

In cognitive radio networks, primary users have priority over the regulated radio spectrum. Secondary users may use residual air time. We focus on the problem of meeting on a common channel by a group of secondary users. The goal is to make the users rendezvous on a common channel in a minimum amount of time. The jump-stay algorithm has been created by Lin et al. to solve this problem. We construct a new analytic model for the two-user expected time to rendezvous in the jump-stay algorithm that better reflects its performance. For the sake of comparison, we also evaluate the performance of the jump-stay algorithm through simulation

Preventing the cluster formation attack against the hierarchical OLSR protocol

The Hierarchical Optimized Link State Routing (HOLSR) protocol enhances the scalability and heterogeneity of traditional OLSR-based Mobile Ad-Hoc Networks (MANETs). It organizes the network in logical levels and nodes in clusters. In every cluster, it implements the mechanisms and algorithms of the original OLSR to generate and to distribute control traffic information. However, the HOLSR protocol was designed with no security in mind. Indeed, it both inherits, from OLSR, and adds new security threats. For instance, the existence of misbehaving nodes can highly affect important HOLSR operations, such as the cluster formation. Cluster IDentification (CID) messages are implemented to organize a HOLSR network in clusters. In every message, the hop count field indicates to the receiver the distance in hops to the originator. An attacker may maliciously alter the hop count field. As a consequence, a receiver node may join a cluster head farther away than it appears. Then, the scalability properties in a HOLSR network is affected by an unbalanced distribution of nodes per cluster. We present a s

Mitigation of topology control traffic attacks in OLSR networks

The core of the Optimized Link State Routing (OLSR) protocol is the selection of Multipoint Relays (MPRs) as a flooding mechanism for distributing control traffic messages. A node in an OLSR network, selects its MPR set such that all two-hop neighbors are reachable through, at least, one MPR. However, if an MPR misbehaves during the execution of the protocol, the connectivity of the network is compromised. Additional coverage in the selection of the MPRs helps to mitigate the effect of control traffic attacks. RFC3626 defines the selection of MPRs with additional coverage. Nevertheless, the overhead of the network increases due to the added number of control traffic messages. In this paper, we propose an improved MPR selection with additional coverage. Every node selects, if it is possible, k + 1 disjoint MPR sets. The union of those sets, is a k-robust-MPR set. Thus, given a node, alternative paths are created to reach any destination two-hops away. We test both approaches against two kinds of adversaries misbehaving during the execution of the protocol. Our proposed MPR selection with additional coverage mitigates the effect of control traffic attacks by offering equivalent protectio

Chitosan feasibility to retain retinal stem cell phenotype and slow proliferation for retinal transplantation

Retinal stem cells (RSCs) are promising in cell replacement strategies for retinal diseases. RSCs can migrate, differentiate, and integrate into retina. However, RSCs transplantation needs an adequate support; chitosan membrane (ChM) could be one, which can carry RSCs with high feasibility to support their integration into retina. RSCs were isolated, evaluated for phenotype, and subsequently grown on sterilized ChM and polystyrene surface for 8 hours, 1, 4, and 11 days for analysing cell adhesion, proliferation, viability, and phenotype. Isolated RSCs expressed GFAP, PKC, isolectin, recoverin, RPE65, PAX-6, cytokeratin 8/18, and nestin proteins. They adhered (28 ± 16%, 8 hours) and proliferated (40 ± 20 cells/field, day 1 and 244 ± 100 cells/field, day 4) significantly low on ChM. However, they maintained similar viability (>95%) and phenotype (cytokeratin 8/18, PAX6, and nestin proteins expression, day 11) on both surfaces (ChM and polystyrene). RSCs did not express alpha-SMA protein on both surfaces. RSCs express proteins belonging to epithelial, glial, and neural cells, confirming that they need further stimulus to reach a final destination of differentiation that could be provided in in vivo condition. ChM does not alternate RSCs behaviour and therefore can be used as a cell carrier so that slow proliferating RSCs can migrate and integrate into retina

Thiamethoxam in Papaya (Carica papaya Linnaeus) Agroecosystems

Papaya (Carica papaya L.) is a profitable fruit of economic and food importance in Mexico and Central America. Veracruz is the state in Mexico with the highest cultivable area, eventhough its production presents numerous phytosanitary problems, which are being faced with the use of the pesticide thiamethoxam. The aim of this study was to make a diagnosis of the use and management of thiamethoxam in papaya agroecosystems in the municipality of Cotaxtla, Veracruz. Two surveys were applied, one to a 30% of the total number of producers organized by an association dedicated to papaya culture, and the other survey was through key informants, both surveys were designed using the snowball sampling, a non-probability sampling technique. The results indicate that 6% of papaya producers use mainly the pesticide thiamethoxam, which belongs to the chemical group of neonicotinoids. It was found out that for five years there have been records of thiamethoxam use in vertisoils. During the cycle of papaya cultivation the producers use a maximum dose of 3 L/ha and a minimum dose of 250 ml/ha per crop cycle. One hundred per cent of those who apply thiamethoxam are not aware of its use and efficient management, nor of the damage they are doing or have caused to agroecosystems