Printing a People: Constructing Identity in National Currency

It is not surprising that inequality exists in Central America given its turbulent history of class conflict and racial discrimination. This history must not be forgotten when considering countries such as Honduras and Mexico as it has helped shape their national personas. Nevertheless, analyzing inequality in Central American societies is no simple task as most have only enjoyed democracy for a few short decades and can easily recall brutal dictatorships. Furthermore, when looking at national characteristics that form the countries’ identities such as national anthems, flags, or currency the tumultuous past and societal problems are often conveniently left out. In order to understand how the State in Honduras and Mexico has constructed a public history and thus national identity, the currency of the respective Central American countries may be used as a vehicle of exploration. I found that by looking at the images depicted on Mexican Pesos and Honduran Lempiras, the countries’ problems of indigenous inequality become evident. The currencies represent countries of proud historical figures, integrated populations, and rich landscapes by including imagery of war heroes, indigenous ruins, or natural resources. However, I argue that the historical portrait produced by the imagery, manufactured in the 20th century, is not so much an accurate portrayal of the countries’ indigenous history as it is an illustration employed by colonial hierarchy to establish a unified modern identity that justifies the exploitation of classes. My project highlights the fact that many indigenous groups are underrepresented and mistreated in Honduras, a country that has experienced a movement to ‘whiten’ its society ever since the times of colonization. Likewise, the figures of indigenous culture on the Mexican currency routinely appear in positions that portray them as inferior to figures of Hispanic identity, which highlight the societal problem of defining ‘Indians’ as poverty-stricken individuals stuck in the Third World. However, all is not lost as there have been multiple efforts on behalf of the underrepresented minority groups to gain equal rights and representation in government to break inequality

Early neuronal accumulation of DNA double strand breaks in Alzheimer's disease.

The maintenance of genomic integrity is essential for normal cellular functions. However, it is difficult to maintain over a lifetime in postmitotic cells such as neurons, in which DNA damage increases with age and is exacerbated by multiple neurological disorders, including Alzheimer's disease (AD). Here we used immunohistochemical staining to detect DNA double strand breaks (DSBs), the most severe form of DNA damage, in postmortem brain tissues from patients with mild cognitive impairment (MCI) or AD and from cognitively unimpaired controls. Immunostaining for γH2AX-a post-translational histone modification that is widely used as a marker of DSBs-revealed increased proportions of γH2AX-labeled neurons and astrocytes in the hippocampus and frontal cortex of MCI and AD patients, as compared to age-matched controls. In contrast to the focal pattern associated with DSBs, some neurons and glia in humans and mice showed diffuse pan-nuclear patterns of γH2AX immunoreactivity. In mouse brains and primary neuronal cultures, such pan-nuclear γH2AX labeling could be elicited by increasing neuronal activity. To assess whether pan-nuclear γH2AX represents DSBs, we used a recently developed technology, DNA damage in situ ligation followed by proximity ligation assay, to detect close associations between γH2AX sites and free DSB ends. This assay revealed no evidence of DSBs in neurons or astrocytes with prominent pan-nuclear γH2AX labeling. These findings suggest that focal, but not pan-nuclear, increases in γH2AX immunoreactivity are associated with DSBs in brain tissue and that these distinct patterns of γH2AX formation may have different causes and consequences. We conclude that AD is associated with an accumulation of DSBs in vulnerable neuronal and glial cell populations from early stages onward. Because of the severe adverse effects this type of DNA damage can have on gene expression, chromatin stability and cellular functions, DSBs could be an important causal driver of neurodegeneration and cognitive decline in this disease

Dynamin-related protein 1 is required for normal mitochondrial bioenergetic and synaptic function in CA1 hippocampal neurons.

Disrupting particular mitochondrial fission and fusion proteins leads to the death of specific neuronal populations; however, the normal functions of mitochondrial fission in neurons are poorly understood, especially in vivo, which limits the understanding of mitochondrial changes in disease. Altered activity of the central mitochondrial fission protein dynamin-related protein 1 (Drp1) may contribute to the pathophysiology of several neurologic diseases. To study Drp1 in a neuronal population affected by Alzheimer's disease (AD), stroke, and seizure disorders, we postnatally deleted Drp1 from CA1 and other forebrain neurons in mice (CamKII-Cre, Drp1lox/lox (Drp1cKO)). Although most CA1 neurons survived for more than 1 year, their synaptic transmission was impaired, and Drp1cKO mice had impaired memory. In Drp1cKO cell bodies, we observed marked mitochondrial swelling but no change in the number of mitochondria in individual synaptic terminals. Using ATP FRET sensors, we found that cultured neurons lacking Drp1 (Drp1KO) could not maintain normal levels of mitochondrial-derived ATP when energy consumption was increased by neural activity. These deficits occurred specifically at the nerve terminal, but not the cell body, and were sufficient to impair synaptic vesicle cycling. Although Drp1KO increased the distance between axonal mitochondria, mitochondrial-derived ATP still decreased similarly in Drp1KO boutons with and without mitochondria. This indicates that mitochondrial-derived ATP is rapidly dispersed in Drp1KO axons, and that the deficits in axonal bioenergetics and function are not caused by regional energy gradients. Instead, loss of Drp1 compromises the intrinsic bioenergetic function of axonal mitochondria, thus revealing a mechanism by which disrupting mitochondrial dynamics can cause dysfunction of axons

Analyzing the Multiwavelength Spectrum and Variability of BL Lacertae During the July 1997 Outburst

The multiwavelength spectrum of BL Lacertae during its July 1997 outburst is analyzed in terms of different variations of the homogeneous leptonic jet model for the production of high-energy radiation from blazars. We find that a two-component gamma-ray spectrum, consisting of a synchrotron self-Compton and an external Compton component, is required in order to yield an acceptable fit to the broadband spectrum. Our analysis indicates that in BL Lac, unlike other BL Lac objects, the broad emission line region plays an important role for the high-energy emission. Several alternative blazar jet models are briefly discussed. In the appendix, we describe the formalism in which the process of Comptonization of reprocessed accretion disk photons is treated in the previously developed blazar jet simulation code which we use.Comment: Now accepted for publication in The Astronomical Journal. Significantly extended discussion w.r.t. original version. 3 Figures included using epsf.sty, rotate.st

Point-like gamma ray sources as signatures of distant accelerators of ultra high energy cosmic rays

We discuss the possibility of observing distant accelerators of ultra high energy cosmic rays in synchrotron gamma rays. Protons propagating away from their acceleration sites produce extremely energetic electrons during photo-pion interactions with cosmic microwave background photons. If the accelerator is embedded in a magnetized region, these electrons will emit high energy synchrotron radiation. The resulting synchrotron source is expected to be point-like and detectable in the GeV-TeV energy range if the magnetic field is at the nanoGauss level.Comment: 4 pages 2 figures. To be published in PR

The AGASA/SUGAR Anisotropies and TeV Gamma Rays from the Galactic Center: A Possible Signature of Extremely High-energy Neutrons

Recent analysis of data sets from two extensive air shower cosmic ray detectors shows tantalizing evidence of an anisotropic overabundance of cosmic rays towards the Galactic Center (GC) that ``turns on'' around $10^{18}$ eV. We demonstrate that the anisotropy could be due to neutrons created at the Galactic Center through charge-exchange in proton-proton collisions, where the incident, high energy protons obey an $\sim E^{-2}$ power law associated with acceleration at a strong shock. We show that the normalization supplied by the gamma-ray signal from EGRET GC source 3EG J1746-2851 -- ascribed to pp induced neutral pion decay at GeV energies -- together with a very reasonable spectral index of 2.2, predicts a neutron flux at $\sim 10^{18}$ eV fully consistent with the extremely high energy cosmic ray data. Likewise, the normalization supplied by the very recent GC data from the HESS air-Cerenkov telescope at \~TeV energies is almost equally-well compatible with the $\sim 10^{18}$ eV cosmic ray data. Interestingly, however, the EGRET and HESS data appear to be themselves incompatible. We consider the implications of this discrepancy. We discuss why the Galactic Center environment can allow diffusive shock acceleration at strong shocks up to energies approaching the ankle in the cosmic ray spectrum. Finally, we argue that the shock acceleration may be occuring in the shell of Sagittarius A East, an unusual supernova remnant located very close to the Galactic Center. If this connection between the anisotropy and Sagittarius A East could be firmly established it would be the first direct evidence for a particular Galactic source of cosmic rays up to energies near the ankle.Comment: 57 pages, 2 figure

ATCA radio imaging of the ProPlyD-like objects in the giant HII region NGC 3603

Three cometary-shaped objects in the giant HII region NGC 3603, originally found and identified as proto-planetary disks (ProPlyDs) by Brandner et al. 2000 using HST+VLT in the optical and near-infrared, have been detected with the Australia Telescope Compact Array (ATCA) in the radio continuum at 3 and 6cm. All three ProPlyD-like objects are clearly resolved with an extent of a few arcseconds. The integrated 6cm fluxes are up to 1.3 times higher than the 3cm fluxes with spectral indices averaged over the whole clump between $\alpha=-0.1$ and -0.5 ($S_\nu \propto \nu^{\alpha}$), indicating the likely presence of non-thermal emission in at least some of the sources. All measured fluxes are at least one order of magnitude higher than those predicted by Brandner et al. 2000. Due to the unexpectedly large radio luminosities of the ProPlyD-like features and because the radio emission is extended a (proto-)stellar origin of the non-thermal emission from a dust enshrouded star appears unlikely. Instead we propose that magnetized regions within the envelope of the ProPlyD-like nebulae exist. (abridged)Comment: 25 pages, 10 figures, accepted for publication in ApJ; Fig.1 can be obtained from [email protected]