Epidermal Langerhans Cells are Dispensable for Humoral and Cell-Mediated Immunity Elicited by Gene Gun Immunization.

Gene gun immunization, i.e., bombardment of skin with DNA-coated particles, is an efficient method for the administration of DNA vaccines. Direct transfection of APC or cross-presentation of exogenous Ag acquired from transfected nonimmune cells enables MHC-I-restricted activation of CD8(+) T cells. Additionally, MHC-II-restricted presentation of exogenous Ag activates CD4(+) Th cells. Being the principal APC in the epidermis, Langerhans cells (LC) seem ideal candidates to accomplish these functions. However, the dependence on LC of gene gun-induced immune reactions has not yet been demonstrated directly. This was primarily hampered by difficulties to discriminate the contributions of LC from those of other dermal dendritic cells. To address this problem, we have used Langerin-diphtheria toxin receptor knockin mice that allow for selective inducible ablation of LC. LC deficiency, even over the entire duration of experiments, did not affect any of the gene gun-induced immune functions examined, including proliferation of CD4(+) and CD8(+) T cells, IFN-gamma secretion by spleen cells, Ab production, CTL activity, and development of protective antitumor immunity.

Langerin(+) Dermal Dendritic Cells Are Critical for CD8(+) T Cell Activation and IgH gamma-1 Class Switching in Response to Gene Gun Vaccines

The C-type lectin langerin/CD207 was originally discovered as a specific marker for epidermal Langerhans cells (LC). Recently, additional and distinct subsets of langerin(+) dendritic cells (DC) have been identified in lymph nodes and peripheral tissues of mice. Although the role of LC for immune activation or modulation is now being discussed controversially, other langerin(+) DC appear crucial for protective immunity in a growing set of infection and vaccination models. In knock-in mice that express the human diphtheria toxin receptor under control of the langerin promoter, injection of diphtheria toxin ablates LC for several weeks whereas other langerin(+) DC subsets are replenished within just a few days. Thus, by careful timing of diphtheria toxin injections selective states of deficiency in either LC only or all langerin(+) cells can be established. Taking advantage of this system, we found that, unlike selective LC deficiency, ablation of all langerin(+) DC abrogated the activation of IFN-gamma producing and cytolytic CD8(+) T cells after gene gun vaccination. Moreover, we identified migratory langerin(+) dermal DC as the subset that directly activated CD8(+) T cells in lymph nodes. Langerin(+) DC were also critical for IgG1 but not IgG2a Ab induction, suggesting differential polarization of CD4(+) T helper cells by langerin(+) or langerin-negative DC, respectively. In contrast, protein vaccines administered with various adjuvants induced IgG1 independently of langerin(+) DC. Taken together, these findings reflect a highly specialized division of labor between different DC subsets both with respect to Ag encounter as well as downstream processes of immune activation. The Journal of Immunology, 2011, 186: 1377-1383.

Learning how (not) to fire a gun: combatant training and civilian victimization

What is the relationship between the type of training combatants receive upon recruitment into an armed group and their propensity to abuse civilians in civil war? Does military training or political training prevent or exacerbate the victimization of civilians by armed non-state actors? While the literature on civilian victimization has expanded rapidly, few studies have examined the correlation between abuse of civilians and the modes of training that illegal armed actors receive. Using a simple formal model, we develop hypotheses regarding this connection and argue that while military training should not decrease the probability that a combatant engages in civilian abuse, political training should. We test these hypotheses using a new survey consisting of a representative sample of approximately 1,500 demobilized combatants from the Colombian conflict, which we match with department-level data on civilian casualties. The empirical analysis confirms our hypotheses about the connection between training and civilian abuse and the results are robust to adding a full set of controls both at the department and at the individual level

Termination of diamond surfaces with hydrogen, oxygen and fluorine using a small, simple plasma gun

We have formed and characterized polycrystalline diamond films with surfaces having hydrogen terminations, oxygen terminations, or fluorine terminations, using a small, simple and novel plasma gun to bombard the diamond surface, formed by plasma assisted CVD in a prior step, with ions of the wanted terminating species. The potential differences between surface regions with different terminations were measured by Kelvin Force Microscopy (KFM). The highest potential occurred for oxygen termination regions and the lowest for fluorine. The potential difference between regions with oxygen terminations and hydrogen terminations was about 80 mV, and between regions with hydrogen terminations and fluorine terminations about 150 mV. Regions with different terminations were identified and imaged using the secondary electron signal provided by scanning electron microscopy (SEM). since this signal presents contrast for surfaces with different electrical properties. The wettability of the surfaces with different terminations was evaluated, measuring contact angles. The sample with oxygen termination was the most hydrophilic, with a contact angle of 75 degrees. hydrogen-terminated regions with 83 degrees, and fluorine regions 93 degrees, the most hydrophobic sample. (C) 2010 Elsevier B.V. All rights reserved.

High-density gas aggregation nanoparticle gun applied to the production of SmCo clusters

We describe in this article the application of a high-density gas aggregation nanoparticle gun to the production and characterization of high anisotropy SmCo nanoparticles. We give a detailed description of the simple but efficient experimental apparatus with a focus on the microscopic processes of the gas aggregation technique. Using high values of gas flux (similar to 45 sccm) we are able to operate in regimes of high collimation of material. In this regime, as we explain in terms of a phenomenological model, the power applied to the sputtering target becomes the main variable to change the size of the clusters. Also presented are the morphological, structural, and magnetic characterizations of SmCo nanoparticles produced using 10 and 50 W of sputtering power. These values resulted in mean sizes of similar to 12 and similar to 20 nm. Significant differences are seen in the structural and magnetic properties of the samples with the 50 W sample showing a largely enhanced crystalline structure and magnetic anisotropy.

There's a black boy dead and a migloo holding a gun : death, Aboriginality and history in Australian adolescent literature

This essay is concerned with the extent to which the attitudes and ideologies of colonial discourse continue to influence contemporary signifying practices in Australian adolescent historical fiction. Under scrutiny are three novels which take issue with the violent aspects of colonisation when so many members of the Indigenous population either died or were forcibly displaced: Melissa Lucashenko’s Killing Darcy, Gary Crew’s No Such Country and Mark Svendsen’s Poison Under Their Lips. Although these texts share a desire to interrogate monolithic versions of Australia’s history, it is argued that such motivations offer no guarantee that the implied audience is positioned to come to an understanding of perspectives belonging to ex-centric Others.

O novo sistema de análise prévia dos atos de concentração e a questão do Gun-Jumping: traçando parâmetros para as empresas

Em 29 de maio de 2012 entrou em vigor a Lei nº 12.529/2011, que introduziu no Brasil o sistema de análise prévia dos atos de concentração. Nesse novo regime, as empresas deverão preservar as condições de concorrência entre si e não mais poderão consumar a operação antes de sua aprovação pelo Conselho Administrativo de Defesa Econômica (CADE), sob pena de violarem as regras do sistema de análise prévia das operações, i.e., praticarem gun-jumping ilegal. Contudo, nem a Nova Lei, nem o Novo Regimento Interno do CADE especificaram quais práticas implicariam a consumação da operação. Dessa forma, o presente trabalho buscou identificar parâmetros, através da experiência americana e europeia e da análise de acordos de preservação da reversibilidade da operação, que pudessem auxiliar as empresas a conduzirem suas atividades no momento que antecede a aprovação da operação.

An economic model of gun control

Guns stolen from law-abiding households provide the principal source of guns for criminals. The lethality of crime instruments increases with the availability of guns, so the gun market is subject to externalities that generate excessive ownership and inadequate spending on protective measures to deter gun theft. One motive for gun ownership is self defense, and the gun market is subject to coordination failure: the more guns purchased lawfully, the more will be stolen by criminals, so the greater the incentive for lawful . consumers to purchase guns for self defense. As a result, there may be multiple equilibria in the gun market and more than one equilibrium crime rate. We show that a simple refundable deposit for guns will internalize the externalities in the gun market and may cause large downward jumps in gun ownership, the lethality of crime instruments, and the social costs of crime.

Al-based anodic oxide films structure observation using field emission gun scanning electron microscopy

In the present work, the anodic oxide films of Al, Al-Cu 4.5% and Al-Si 6.5% alloys are formed using direct and pulse current. In the case of Al-Cu and Al-Si alloys, the electrolyte used contains sulfuric acid and oxalic acid, meanwhile for Al the electrolyte contains sulfuric acid only. Al-Cu alloy was submitted to a heat treatment in order to decrease the effect of inter metallic phase theta upon the anodic film structure. Fractured samples were observed using a field emission gun scanning electron microscope JSM-6330F at (LME)/Brazilian Synchrotron Light Laboratory (LNLS), Campinas, SP, Brazil. The oxide film images enable evaluation of the pore size and form with a resolution similar to the transmission electron microscope (TEM) resolution. It is also observed that the anodizing process using pulse current produces an irregular structure of pore walls, and by direct cur-rent it is produced a rectilinear pore wall. (c) 2005 Elsevier B.V. All rights reserved.