High Density Preheating Effects on Q-ball Decays and MSSM Inflation

Non-perturbative preheating decay of post-inflationary condensates often results in a high density, low momenta, non-thermal gas. In the case where the non-perturbative classical evolution also leads to Q-balls, this effect shields them from instant dissociation, and may radically change the thermal history of the universe. For example, in a large class of inflationary scenarios, motivated by the MSSM and its embedding in string theory, the reheat temperature changes by a multiplicative factor of $10^{12}$.Comment: 4 page

Making Immigrants into Criminals: Legal Processes of Criminalization in the Post-IIRIRA Era

During a post-election TV interview that aired mid-November 2016, then President-Elect Donald Trump claimed that there are millions of so-called “criminal aliens” living in the United States: “What we are going to do is get the people that are criminal and have criminal records, gang members, drug dealers, we have a lot of these people, probably two million, it could be even three million, we are getting them out of our country or we are going to incarcerate.” This claim is a blatant misrepresentation of the facts. A recent report by the Migration Policy Institute suggests that just over 800,000 (or 7 percent) of the 11 million undocumented individuals in the United States have criminal records. Of this population, 300,000 individuals are felony offenders and 390,000 are serious misdemeanor offenders — tallies which exclude more than 93 percent of the resident undocumented population (Rosenblum 2015, 22-24).[1] Moreover, the Congressional Research Service found that 140,000 undocumented migrants — or slightly more than 1 percent of the undocumented population — are currently serving time in prison in the United States (Kandel 2016). The facts, therefore, are closer to what Doris Meissner, former Immigration and Naturalization Service (INS) Commissioner, argues: that the number of “criminal aliens” arrested as a percentage of all fugitive immigration cases is “modest” (Meissner et al. 2013, 102-03). The facts notwithstanding, President Trump’s fictional tally is important to consider because it conveys an intent to produce at least this many people who — through discourse and policy — can be criminalized and incarcerated or deported as “criminal aliens.” In this article, we critically review the literature on immigrant criminalization and trace the specific laws that first linked and then solidified the association between undocumented immigrants and criminality. To move beyond a legal, abstract context, we also draw on our quantitative and qualitative research to underscore ways immigrants experience criminalization in their family, school, and work lives. The first half of our analysis is focused on immigrant criminalization from the late 1980s through the Obama administration, with an emphasis on immigration enforcement practices first engineered in the 1990s. Most significant, we argue, are the 1996 Illegal Immigration Reform and Immigration Responsibility Act (IIRIRA) and the 1996 Antiterrorism and Effective Death Penalty Act (AEDPA). The second section of our analysis explores the social impacts of immigrant criminalization, as people’s experiences bring the consequences of immigrant criminalization most clearly into focus. We approach our analysis of the production of criminality of immigrants through the lens of legal violence (Menjivar and Abrego 2012), a concept designed to understand the immediate and long-term harmful effects that the immigration regime makes possible. Instead of narrowly focusing only on the physical injury of intentional acts to cause harm, this concept broadens the lens to include less visible sources of violence that reside in institutions and structures and without identifiable perpetrators or incidents to be tabulated. This violence comes from structures, laws, institutions, and practices that, similar to acts of physical violence, leave indelible marks on individuals and produce social suffering. In examining the effects of today’s ramped up immigration enforcement, we turn to this concept to capture the violence that this regime produces in the lives of immigrants. Immigrant criminalization has underpinned US immigration policy over the last several decades. The year 1996, in particular, was a signal year in the process of criminalizing immigrants. Having 20 years to trace the connections, it becomes evident that the policies of 1996 used the term “criminal alien” as a strategic sleight of hand. These laws established the concept of “criminal alienhood” that has slowly but purposefully redefined what it means to be unauthorized in the United States such that criminality and unauthorized status are too often considered synonymous (Ewing, Martínez, and Rumbaut 2015). Policies that followed in the 2000s, moreover, cast an increasingly wider net which continually re-determined who could be classified as a “criminal alien,” such that the term is now a mostly incoherent grab bag. Simultaneously and in contrast, the practices that produce “criminal aliens” are coherent insofar as they condition immigrant life in the United States in now predictable ways. This solidity allows us to turn in our conclusion to some thoughts about the likely future of US immigration policy and practice under President Trump. [1] These numbers are based on the assumption that “unauthorized immigrants and lawful noncitizens commit crimes at similar rates” (Rosenblum 2015, 22). However, there is research that provides good support that criminality among the undocumented is lower than for the foreign-born population overall (Rumbaut 2009; Ewing, Martínez, and Rumbaut 2015)

The effect of a small vegetation dieback event on salt marsh sediment transport

Vegetation is a critical component of the ecogeomorphic feedbacks that allow a salt marsh to build soil and accrete vertically. Vegetation dieback can therefore have detrimental effects on marsh stability, especially under conditions of rising sea levels. Here, we report a variety of sediment transport measurements associated with an unexpected, natural dieback in a rapidly prograding marsh in the Altamaha River Estuary, Georgia. We find that vegetation mortality led to a significant loss in elevation at the dieback site as evidenced by measurements of vertical accretion, erosion, and surface topography compared to vegetated refer- ence areas. Below-ground vegetation mortality led to reduced soil shear strength. The dieback site displayed an erosional, concave-up topographic profile, in contrast to the reference sites. At the location directly impacted by the dieback, there was a reduction in flood dominance of suspended sediment concentration. Our work illustrates how a vegetation disturbance can at least temporarily reverse the local trajectory of a prograding marsh and produce complex patterns of sediment transport

Reconciling models and measurements of marsh vulnerability to sealevel rise

Tidal marsh survival in the face of sea level rise (SLR) anddeclining sediment supply often depends on the ability ofmarshes to build soil vertically. However, numerical models typically predict survival under rates of SLR that farexceedfield-based measurements of vertical accretion. Here, we combine novel measurements from sevenU.S. Atlantic Coast marshes and data from 70 additional marshes from around the world to illustrate that—over con-tinental scales—70% of variability in marsh accretion rates can be explained by suspended sediment concentratin(SSC) and spring tidal range (TR). Apparent discrepancies between models and measurements can be explained bydiffering responses in high marshes and low marshes,the latter of which accretes faster for a given SSC andTR. Together these results help bridge the gap between models and measurements, and reinforce the paradigm thatsediment supply is the key determinant of wetland vulnerability at continental scales

The Role Of Suspended Sediment In Assessing Coastal Wetland Vulnerability

Coastal wetlands sequester carbon, attenuate waves and storm surge, filter out nutrients and pollutants, and act as nursery habitat for important fisheries. The value of these ecosystems is underscored by their vulnerability to climate change, especially sea level rise. To persist under the threat of rising sea level, coastal wetlands must build elevation vertically. Delivery of sediment to the marsh during tidal flooding is a key component in the ecogeomorphic feedbacks that lead to elevation gain. Despite the importance of suspended sediment to assessing coastal wetland vulnerability, many questions remain unanswered. This dissertation addresses the impact of suspended sediment concentration on wetland geomorphology from fine-scale processes to global patterns and from thriving systems to those experiencing significant environmental change. In Chapter I, I explore alterations to sediment transport and geomorphology caused by an acute vegetation disturbance in a Georgia saltmarsh. My results showed that the loss of vegetation was reversed the trajectory of the site from a prograding marsh to an eroding marsh. In Chapter II, I investigate how suspended sediment travels across the marsh platform using high frequency, long-term measurements in the Plum Island Estuary, Massachusetts. In contrast to the current paradigm, I found that sediment supply in the marsh interior is largely decoupled from channel sediment supply. Chapter III focuses on the role of sediment transport in mangrove encroachment into salt marshes in Australia. My work suggests that mangroves do not inhibit the ability of salt marsh to accrete vertically and that the removal of mangroves to preserve salt marsh would be ineffective. In Chapter IV, I analyze the relationship between suspended sediment concentration, tidal range, and accretion in salt marshes from around the world. My work emphasizes the importance of mineral accretion and marsh elevation when making predictions about marsh response to sea level rise. These results help bridge the gap between numerical models which predict marshes are capable of surviving high rates of relative sea level rise and field studies which suggest drowning at much lower rates. As a whole, my dissertation demonstrates that physical processes and the ways in which biology mediate these processes are critical to the ability of coastal wetlands to persist. As the rate of sea level rise continues to accelerate, it is increasingly important to understand the controls on vertical elevation growth in coastal wetlands at the scale of several meters to thousands of kilometers and in pristine systems to degraded environments

Scale invariance and viscosity of a two-dimensional Fermi gas

We investigate the collective excitations of a harmonically trapped two-dimensional Fermi gas from the collisionless (zero sound) to the hydrodynamic (first sound) regime. The breathing mode, which is sensitive to the equation of state, is observed at a frequency two times the dipole mode frequency for a large range of interaction strengths and temperatures, and the amplitude of the breathing mode is undamped. This provides evidence for a dynamical SO(2,1) scaling symmetry of the two-dimensional Fermi gas. Moreover, we investigate the quadrupole mode to measure the shear viscosity of the two-dimensional gas and study its temperature dependence

Roles for retinoid-X-receptors in solar UV-induced melanocyte homeostasis and melanomagenesis

Melanoma is the deadliest form of skin cancer, arising from malignant transformation of pigment-producing melanocytes. The primary risk factor for melanoma and other skin cancers is DNA damage resulting from unprotected solar ultraviolet radiation (UVR). If incorrectly repaired, this damage can result in incorporation of mutations that cause aberrant cell cycling and/or other functional defects that promote tumorigenesis. Rates of melanoma incidence are on the rise in Oregon and throughout the U.S.; thus better understanding of the molecular mechanisms underlying its formation and progression are needed for the purposes of diagnosis and therapeutic targeting. In this work we have used mouse models to establish multiple roles for Retinoid-X-Receptors (RXRs) in UVR-induced melanocyte homeostasis and melanomagenesis. Ablation of RXRα expression in epidermal keratinocytes (Rxrα[superscript ep-/-]) enhances melanocyte proliferation following an acute UVR dose; stemming from increased expression of mitogenic paracrine factors. Combining Rxrα[superscript ep-/-] mice with activated CDK4 (R24C) or oncogenic NRAS (Q61K) mutations in a bigenic model results in enhanced UVR-induced melanomagenesis compared to control mice with the CDK4 or NRAS mutations alone. These melanomas show increased expression of malignant melanoma and tumor angiogenesis markers; and increased metastases of pigment-producing cells to draining lymph nodes. Interestingly, the tumor adjacent normal skin of these mice have reduced expression of p53 and PTEN, tumor suppressors commonly downregulated in melanoma; suggesting that in addition to enhancing melanomagenesis, keratinocytic RXRα loss results in a microenvironment favorable to primary tumor formation. By ablating RXRs α and β specifically in the melanocytes (Rxrα/β[superscript mel-/-]), we observed differential alterations in the post-UVR survival of the melanocytes and the dermal fibroblasts. Loss of melanocytic RXR expression results in defective homeostasis of chemoattractive/chemorepulsive chemokines secreted by melanocytes to attract macrophages and other immune cells post-UVR. An overall reduction of immune cell infiltration in Rxrα/β[superscript mel-/-] mice results in less available interferon-γ available in the microenvironment which has a negative effect on post-UVR survival of fibroblasts and melanocytes. However, as the genetic defect in these mice is specifically in the melanocytes, there are dysregulations in cell-intrinsic apoptosis signaling that allow these cells to overcome reduced available IFN-γ and have enhanced survival post-UVR. Therefore RXRs in melanocytes modulate post-UVR survival of dermal fibroblasts in a "non-cell autonomous" manner, underscoring their role in immune surveillance; while independently mediating post-UVR melanocyte survival in a "cell autonomous" manner. Altogether these results establish a multitude of roles for RXRs in melanocyte homeostasis and melanomagenesis, and identifies them as potential targets for melanoma diagnosis and therapeutics

Functional Bosonization of Non-Relativistic Fermions in (2+1)(2+1) Dimensions

We analyze the universality of the bosonization rules in non-relativistic fermionic systems in $(2+1)d$. We show that, in the case of linear fermionic dispersion relations, a general fermionic theory can be mapped into a gauge theory in such a way that the fermionic density maps into a magnetic flux and the fermionic current maps into a transverse electric field. These are universal rules in the sense that they remain valid whatever the interaction considered. We also show that these rules are universal in the case of non-linear dispersion relations provided we consider only density-density interactions. We apply the functional bosonization formalism to a non-relativistic and non-local massive Thirring-like model and evaluate the spectrum of collective excitations in several limits. In the large mass limit, we are able to exactly calculate this spectrum for arbitrary density-density and current-current interactions. We also analyze the massless case and show that it has no collective excitations for any density-density potential in the Gaussian approximation. Moreover, the presence of current interactions may induce a gapless mode with a linear dispersion relation.Comment: 26 Pages, LaTeX, Final version to appear in International Journal of Modern Physics

Onset of runaway fragmentation of salt marshes

Salt marshes are valuable but vulnerable coastal ecosystems that adapt to relative sea level rise (RSLR) by accumulating organic matter and inorganic sediment. The natural limit of these processes defines a threshold rate of RSLR beyond which marshes drown, resulting in ponding and conversion to open waters. We develop a simplified formulation for sediment transport across marshes to show that pond formation leads to runaway marsh fragmentation, a process characterized by a self-similar hierarchy of pond sizes with power-law distributions. We find the threshold for marsh fragmentation scales primarily with tidal range and that sediment supply is only relevant where tides are sufficient to transport sediment to the marsh interior. Thus the RSLR threshold is controlled by organic accretion in microtidal marshes regardless of the suspended sediment concentration at the marsh edge. This explains the observed fragmentation of microtidal marshes and suggests a tipping point for widespread marsh loss