The Argo Simulation: I. Quenching of Massive Galaxies at High Redshift as a Result of Cosmological Starvation

Observations show a prevalence of high redshift galaxies with large stellar masses and predominantly passive stellar populations. A variety of processes have been suggested that could reduce the star formation in such galaxies to observed levels, including quasar mode feedback, virial shock heating, or galactic winds driven by stellar feedback. However, the main quenching mechanisms have yet to be identified. Here we study the origin of star formation quenching using Argo, a cosmological, hydrodynamical zoom-in simulation that follows the evolution of a massive galaxy at $z\geq{}2$. This simulation adopts the same sub-grid recipes of the Eris simulations, which have been shown to form realistic disk galaxies, and, in one version, adopts also a mass and spatial resolution identical to Eris. The resulting galaxy has properties consistent with those of observed, massive (M_* ~ 1e11 M_sun) galaxies at z~2 and with abundance matching predictions. Our models do not include AGN feedback indicating that supermassive black holes likely play a subordinate role in determining masses and sizes of massive galaxies at high z. The specific star formation rate (sSFR) of the simulated galaxy matches the observed M_* - sSFR relation at early times. This period of smooth stellar mass growth comes to a sudden halt at z=3.5 when the sSFR drops by almost an order of magnitude within a few hundred Myr. The suppression is initiated by a leveling off and a subsequent reduction of the cool gas accretion rate onto the galaxy, and not by feedback processes. This "cosmological starvation" occurs as the parent dark matter halo switches from a fast collapsing mode to a slow accretion mode. Additional mechanisms, such as perhaps radio mode feedback from an AGN, are needed to quench any residual star formation of the galaxy and to maintain a low sSFR until the present time.Comment: 20 pages, 12 figures, 2 tables, accepted for publication in MNRA

What Communities Can Do to Rein In Payday Lending: Strategies for Successful Local Ordinance Campaigns through a Texas Lens

Because New Mexico has one of the highest consumer usage rates and highest concentrations of payday and title loan shops in the nation,2 we thought it would be an ideal place to measure the public’s knowledge of and interest in these ubiquitous loans. We also measured knowledge of interest rate caps in the context of credit cards, as a point of comparison. Our data are consistent with that of previous studies showing that the general public overwhelmingly supports interest rate caps both in general and for certain types of loans. More uniquely, we also found that many consumers are unaware that there are no interest rate caps on many forms of consumer loans. These data are useful in explaining why consumers do not do more to change the law on interest rate caps

Acoustic properties of fine‐grained sediments from Emerald Basin: Toward an inversion for physical properties using the Biot–Stoll model

Acoustic data from two long cores, comprising marine clays and silts taken from Emerald Basin off Nova Scotia, are presented. High‐resolution measurements of compressional wavevelocity,attenuation, and power law exponent are made using ultrasonic frequencies between 100 to 1000 kHz. The observed values of the frequency dependence of attenuation suggest that a nonconstant Q mechanism is needed to explain these data, and Biot–Stoll theory is used to model the experimental results. An inversion scheme is used to constrain physical parameters in the Biot–Stoll dispersion relation. The inversion shows that there is a restricted range of permeability and grain size. By assigning reasonable values for grain size in the inversion, the Biot–Stoll model predicts unique values for the permeability and frame bulk modulus that agree well with estimates made by other means

Calculation of acoustic parameters by a filter-correlation method

This paper presents the filter correlation method, a technique for extracting consistent and accurate estimates of attenuation parameters from acoustic waveform data. The method minimizes problems associated with short time windows and multipath secondary arrivals. The method comprises two stages: a causal passband filter stage followed by a cross-correlation step. The results of the filter-correlation estimator are compared to those of the spectral difference approach for short time series with and without a secondary multipath arrival. Preliminary analyses of acoustic data collected on cored marine silts and clays show the attenuation properties of these materials cannot be described by a constant Q mechanism. The filter correlation method refines estimates of frequency-dependent velocity, revealing a small but systematic anisotropy between measurements made parallel and transverse to the sediments\u27 bedding plane. The observed velocity anisotropy can be modeled by assuming layered porosity variations in the cored sediments. No systematic anisotropy in attenuation was observed

High-resolution, whole-core magnetic susceptibility data from Leg 130, Ontong Java Plateau

High-resolution, whole-core magnetic susceptibility data, recorded at 3-cm intervals, were obtained for advanced hydraulic piston (APC) cores at Sites 805, 806, and 807 of Leg 130 on the Ontong Java Plateau. In this initial report, we present a preliminary evaluation of these data for their use in core correlations and paleoclimatic studies. The data allow detailed intrasite correlations between the offset APC cores and provide a means for intersite correlations of Pleistocene sediments. Variations in magnetic susceptibility values probably mirror variations in terrestrial influx and may act as proxy indicators of climate. Highly coherent cyclicity, representing Milankovitch orbital frequencies, is exhibited in some intervals and provides the potential to tune sedimentation rates. Postdepositional dissolution of magnetite by reduction diagenesis, which is also reflected in the magnetic susceptibility data, may be a limiting factor in these studies

Loan Sharks, Interest-Rate Caps, and Deregulation

The specter of the loan shark is often conjured by advocates of price deregulation in the market for payday loans. If binding price caps are imposed, the argument goes, loan sharks will be spawned. This is the loan-shark thesis. This Article tests that thesis against the historical record of payday lending in the United States since the origins of the quick-cash business around the Civil War. Two different types of creditors have been derided as “loan sharks” since the epithet was first coined. One used threats of violence to collect its debts but the other did not. The former has been less common than the latter. In the United States, the violent loan sharks proliferated in the small-loan market after state usury caps were raised considerably and these loan sharks dwindled away as a source of credit for working people before interest-rate deregulation began to be adopted at the end of the 1970s. The other type of loan shark thrived both when usury ceilings were very low and when they were very high or even removed. Deregulation does not starve the nonviolent species of loan shark into extinction but instead feeds it. Hence the loanshark thesis is seriously flawed. It does not accord well with the historical record of the market for payday loans

Guestworkers and Exploitation

Are guestworker programs exploitative? Egalitarian and neoclassical theories of exploitation agree that they always are. But these judgments are too indiscriminate. Privileged guests are the exception, and the exception points toward a more sensitive standard for identifying exploitation. This more sensitive standard, the sufficiency theory of exploitation, is used to analyze several guestworker programs. Even when guestworker programs are exploitative, it is argued that the unfairness should be tolerated if the exploitation is modest, not severe, and if the most likely nonexploitative alternative worsens the plight of the disadvantaged

Payday Lending and Personal Bankruptcy

Do payday loan customers form a growing share of bankruptcy petitioners, as many media reports claim? This paper attempts to answer that question and others by analyzing a sample of 3600 bankruptcy petitions filed in selected U.S. counties. From the petitions we can determine the share of debtors that files with payday loans; whether that proportion has been increasing in recent years; how these petitioners compare to other debtors; and whether payday loans are a significant factor in the financial crisis these debtors experience

Hannah Arendt, National Socialism and the Project of Foundation

Foundation is a crucial concept in Hannah Arendt\u27s work. She was especially interested in modern attempts, successful and unsuccessful, to found new bodies politic. Arendt maintained, however, that totalitarian movements were hostile to the project of foundation. Far from seeking to stabilize the world, totalitarianism set the world in motion and tried to keep it moving. But when we turn to National Socialist ideology itself we discover that foundation was vital to the Nazi project; Hitler understood himself as the founder of his people. Arendt\u27s own interpretation of Nazism is mistaken, but I believe that her general theory of foundation can help us to make sense of the National Socialist experience. This article examines the project of foundation in Hitler\u27s Weltanschauung and redeploys Arendt\u27s concepts to explain his unsuccessful attempt to create a new body politic

Attentional demand influences strategies for encoding into visual working memory

Visual selective attention and visual working memory (WM) share the same capacity-limited resources. We investigated whether and how participants can cope with a task in which these 2 mechanisms interfere. The task required participants to scan an array of 9 objects in order to select the target locations and to encode the items presented at these locations into WM (1 to 5 shapes). Determination of the target locations required either few attentional resources (“popout condition”) or an attention-demanding serial search (“non pop-out condition”). Participants were able to achieve high memory performance in all stimulation conditions but, in the non popout conditions, this came at the cost of additional processing time. Both empirical evidence and subjective reports suggest that participants invested the additional time in memorizing the locations of all target objects prior to the encoding of their shapes into WM. Thus, they seemed to be unable to interleave the steps of search with those of encoding. We propose that the memory for target locations substitutes for perceptual pop-out and thus may be the key component that allows for flexible coping with the common processing limitations of visual WM and attention. The findings have implications for understanding how we cope with real-life situations in which the demands on visual attention and WM occur simultaneously. Keywords: attention, working memory, interference, encoding strategie