5,220 research outputs found
Cormac McCarthyâs Border Trilogy and the Modern American Identity Crisis
The narrative trope of the American western is a long-standing literary convention rooted in a convoluted history of conquest, exploration, settlement, and exploitation. At the heart of the western genre is the idyllic vision of self-reliance. From its inception, the United States developed westward, pushing the limits of self-governance into the farthest reaches of empty terrain. As a result, the frontier has long been a symbol of personal liberty, a place where travelers and homesteaders have the freedom to achieve private independence in its purest form. Hollywood has done much to nurture this nostalgic image of prairie life. Iconic silver screen portraits of a bow-legged John Wayne or a cigarillo-chewing Clint Eastwood have endured in the eye of the American imagination for decades, and have perpetuated the classic vision of selfsufficiency in the twentieth and twenty-first centuries. Yet, while the genre has propagated the beliefs and values of an American monoculture, the clichĂ© of the virtuous cowboy who tames the savagery of his natural surroundings is an image that comes under great scrutiny in Cormac McCarthyâs southwestern spaces.
McCarthyâs border novels foreground the problem of cultural identity in the postwar American mythos. In the years following the Second World War, McCarthyâs characters find themselves alone along the high plains of the Mexican-American border. Although the two countries did not fight one another during the war, the border is representative of the cultural barrier that exists between them. At different moments in each of the three novels, protagonists John Grady Cole and Billy Parham come of age in a time period marked by cultural ambiguity. As each of the boys explores the sparse, empty spaces of the mountain terrain, he is faced with existential dilemmas that challenge his sense of self. In their quests, both boys find that their national heritage is obscured by the lifestyles of the indigenous men and women they encounter long the way. As they travel between two countries that seem diametrically opposed to one another in terms of political and cultural ideology, the boys struggle to reconcile a sense of personhood. Since the boys do not feel at home in either country, the problem of unhomeliness forces them to live as cultural refugees in a land of similarly displaced persons. They become, in effect, men without countries. In the lonesome wastes of the desert, where geographical parameters of nations become abstract, the boys inhabit a liminal space outside any national boundary. Having grown up in culturally homogeneous environments, their cultural identity is challenged when they cross the border. It is in this space that they grapple with questions of ethnic heritage, ancestral worldviews, absolute morality, and the notion of a national epistemology
Programming gene expression with combinatorial promoters
Promoters control the expression of genes in response to one or more transcription factors (TFs). The architecture of a promoter is the arrangement and type of binding sites within it. To understand natural genetic circuits and to design promoters for synthetic biology, it is essential to understand the relationship between promoter function and architecture. We constructed a combinatorial library of random promoter architectures. We characterized 288 promoters in Escherichia coli, each containing up to three inputs from four different TFs. The library design allowed for multiple â10 and â35 boxes, and we observed varied promoter strength over five decades. To further analyze the functional repertoire, we defined a representation of promoter function in terms of regulatory range, logic type, and symmetry. Using these results, we identified heuristic rules for programming gene expression with combinatorial promoters
Functional evolution of the feeding system in rodents
The masticatory musculature of rodents has evolved to enable both gnawing at the incisors and chewing at the molars. In particular, the masseter muscle is highly specialised, having extended anteriorly to originate from the rostrum. All living rodents have achieved this masseteric expansion in one of three ways, known as the sciuromorph, hystricomorph and myomorph conditions. Here, we used finite element analysis (FEA) to investigate the biomechanical implications of these three morphologies, in a squirrel, guinea pig and rat. In particular, we wished to determine whether each of the three morphologies is better adapted for either gnawing or chewing. Results show that squirrels are more efficient at muscle-bite force transmission during incisor gnawing than guinea pigs, and that guinea pigs are more efficient at molar chewing than squirrels. This matches the known diet of nuts and seeds that squirrels gnaw, and of grasses that guinea pigs grind down with their molars. Surprisingly, results also indicate that rats are more efficient as well as more versatile feeders than both the squirrel and guinea pig. There seems to be no compromise in biting efficiency to accommodate the wider range of foodstuffs and the more general feeding behaviour adopted by rats. Our results show that the morphology of the skull and masticatory muscles have allowed squirrels to specialise as gnawers and guinea pigs as chewers, but that rats are high-performance generalists, which helps explain their overwhelming success as a group
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Effector memory differentiation increases detection of replication-competent HIV-l in resting CD4+ T cells from virally suppressed individuals.
Studies have demonstrated that intensive ART alone is not capable of eradicating HIV-1, as the virus rebounds within a few weeks upon treatment interruption. Viral rebound may be induced from several cellular subsets; however, the majority of proviral DNA has been found in antigen experienced resting CD4+ T cells. To achieve a cure for HIV-1, eradication strategies depend upon both understanding mechanisms that drive HIV-1 persistence as well as sensitive assays to measure the frequency of infected cells after therapeutic interventions. Assays such as the quantitative viral outgrowth assay (QVOA) measure HIV-1 persistence during ART by ex vivo activation of resting CD4+ T cells to induce latency reversal; however, recent studies have shown that only a fraction of replication-competent viruses are inducible by primary mitogen stimulation. Previous studies have shown a correlation between the acquisition of effector memory phenotype and HIV-1 latency reversal in quiescent CD4+ T cell subsets that harbor the reservoir. Here, we apply our mechanistic understanding that differentiation into effector memory CD4+ T cells more effectively promotes HIV-1 latency reversal to significantly improve proviral measurements in the QVOA, termed differentiation QVOA (dQVOA), which reveals a significantly higher frequency of the inducible HIV-1 replication-competent reservoir in resting CD4+ T cells
High Resolution 8 mm and 1 cm Polarization of IRAS 4A from the VLA Nascent Disk and Multiplicity (VANDAM) Survey
Magnetic fields can regulate disk formation, accretion and jet launching.
Until recently, it has been difficult to obtain high resolution observations of
the magnetic fields of the youngest protostars in the critical region near the
protostar. The VANDAM survey is observing all known protostars in the Perseus
Molecular Cloud. Here we present the polarization data of IRAS 4A. We find that
with ~ 0.2'' (50 AU) resolution at {\lambda} = 8.1 and 10.3 mm, the inferred
magnetic field is consistent with a circular morphology, in marked contrast
with the hourglass morphology seen on larger scales. This morphology is
consistent with frozen-in field lines that were dragged in by rotating material
entering the infall region. The field morphology is reminiscent of rotating
circumstellar material near the protostar. This is the first polarization
detection of a protostar at these wavelengths. We conclude from our
observations that the dust emission is optically thin with {\beta} ~ 1.3,
suggesting that mm/cm-sized grains have grown and survived in the short
lifetime of the protostar.Comment: Accepted to ApJL. 13 pages, 4 figure
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Evasion of autophagy mediated by Rickettsia surface protein OmpB is critical for virulence.
Rickettsia are obligate intracellular bacteria that evade antimicrobial autophagy in the host cell cytosol by unknown mechanisms. Other cytosolic pathogens block different steps of autophagy targeting, including the initial step of polyubiquitin-coat formation. One mechanism of evasion is to mobilize actin to the bacterial surface. Here, we show that actin mobilization is insufficient to block autophagy recognition of the pathogen Rickettsia parkeri. Instead, R. parkeri employs outer membrane protein B (OmpB) to block ubiquitylation of the bacterial surface proteins, including OmpA, and subsequent recognition by autophagy receptors. OmpB is also required for the formation of a capsule-like layer. Although OmpB is dispensable for bacterial growth in endothelial cells, it is essential for R. parkeri to block autophagy in macrophages and to colonize mice because of its ability to promote autophagy evasion in immune cells. Our results indicate that OmpB acts as a protective shield to obstruct autophagy recognition, thereby revealing a distinctive bacterial mechanism to evade antimicrobial autophagy
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