Schools + Politics + Money = Turmoil, Change, Uncertainty

A book review of The Changing Politics of School Finance, edited by Nelda Cambron-McCabe and Allan Odden

Radio-frequency response and contact of impurities in a quantum gas

We investigate the radio-frequency spectroscopy of impurities interacting with a quantum gas at finite temperature. In the limit of a single impurity, we show using Fermi's golden rule that introducing (or injecting) an impurity into the medium is equivalent to ejecting an impurity that is initially interacting with the medium, since the "injection" and "ejection" spectral responses are simply related to each other by an exponential function of frequency. Thus, the full spectral information for the quantum impurity is contained in the injection spectral response, which can be determined using a range of theoretical methods, including variational approaches. We use this property to compute the finite-temperature equation of state and Tan contact of the Fermi polaron. Our results for the contact of a mobile impurity are in excellent agreement with recent experiments and we find that the finite-temperature behavior is qualitatively different compared to the case of infinite impurity mass.Comment: 4 pages, 2 figure

Theory of radio-frequency spectroscopy of impurities in quantum gases

We present a theory of radio-frequency spectroscopy of impurities interacting with a quantum gas at finite temperature. By working in the canonical ensemble of a single impurity, we show that the impurity spectral response is directly connected to the finite-temperature equation of state (free energy) of the impurity. We consider two different response protocols: "injection", where the impurity is introduced into the medium from an initially non-interacting state; and "ejection", where the impurity is ejected from an initially interacting state with the medium. We show that there is a simple mapping between injection and ejection spectra, which is connected to the detailed balance condition in thermal equilibrium. To illustrate the power of our approach, we specialize to the case of the Fermi polaron, corresponding to an impurity atom that is immersed in a non-interacting Fermi gas. For a mobile impurity with a mass equal to the fermion mass, we employ a finite-temperature variational approach to obtain the impurity spectral response. We find a striking non-monotonic dependence on temperature in the impurity free energy, the contact, and the radio-frequency spectra. For the case of an infinitely heavy Fermi polaron, we derive exact results for the finite-temperature free energy, thus generalizing Fumi's theorem to arbitrary temperature. We also determine the exact dynamics of the contact after a quench of the impurity-fermion interactions. Finally, we show that the injection and ejection spectra obtained from the variational approach compare well with the exact spectra, thus demonstrating the accuracy of our approximate method.Comment: 15 pages, 10 figure

Modulation of Cellular Cholesterol and Its Effect on Cornified Envelope Formation in Cultured Human Epidermal Keratinocytes

When cultured human epidermal keratinocytes (NHK) reach confluence they start to differentiate and an increase in the total cellular cholesterol content is observed. This increase parallels the appearance of a characteristic feature of terminal keratinocyte differentiation, the spontaneous formation of cornified envelopes (CE). Synthesis of CE is catalyzed by the plasma membrane-associated transglutaminase (TGm). Supplementation of the medium with inhibitors of cholesterologenesis suppressed increase in cholesterol levels and CE formation but did not interfere with TGm expression or TGm activity. Modulation of the plasma membrane cholesterol-phospholipid ratio of confluent NHK cultures using either pure phospholipid liposomes or liposomes enriched in cholesterol strongly affected spontaneous CE formation. Pure phospholipid liposomes completely inhibited CE formation, whereas cholesterol-enriched liposomes ensured envelope formation, even in the presence of inhibitors of cholesterol synthesis. From these results we conclude that in differentiating NHK an increase in the cellular cholesterol level is part of the differentiation program and is essential for the spontaneous CE formation

Half-Dead Colonies of Montastraea Annularis Release Viable Gametes On A Degraded Reef In The Us Virgin Islands

This article contributes to scholarship on Afroeurope by investigating the intersection of blackness, Africanness, and Europeanness in everyday discourses and social practices in the Netherlands and Italy. We examine how young African-descended Europeans are forging new ways of being both African and European through practices of self-making, which should be understood against both the historical background of colonialism and the contemporary politics of othering. Such practices take on an urgency for these youth, often encompassing a reinvention of Africanness and/or blackness as well as a challenge to dominant, exclusionary understandings of Europeanness. Comparing Afro-Dutch and Afro-Italian modes of self-making, centred on African heritage and roots, we discuss: 1) the emergence of a transnational, Afroeuropean imaginary, distinguished from both white Europe and African-American formations; and 2) the diversity of Afroeuropean modes of self-making, all rooted in distinct histories of colonialism, slavery, and immigration, and influenced by global formations of Africanness and blackness. These new Afro and African identities advanced by young Europeans do not turn away from Europeanness (as dominant identity models would assume: the more African, the less European), nor simply add to Europeanness (“multicultural” identities), nor even mix with Europeanness (“hybrid” identities), but are in and of themselves European

Notch-dependent repression of miR-155 in the bone marrow niche regulates hematopoiesis in an NF-κB-dependent manner

The microRNA miR-155 has been implicated in regulating inflammatory responses and tumorigenesis, but its precise role in linking inflammation and cancer has remained elusive. Here, we identify a connection between miR-155 and Notch signaling in this context. Loss of Notch signaling in the bone marrow (BM) niche alters hematopoietic homeostasis and leads to lethal myeloproliferative-like disease. Mechanistically, Notch signaling represses miR-155 expression by promoting binding of RBPJ to the miR-155 promoter. Loss of Notch/RBPJ signaling upregulates miR-155 in BM endothelial cells, leading to miR-155-mediated targeting of the nuclear factor κB (NF-κB) inhibitor κB-Ras1, NF-κB activation, and increased proinflammatory cytokine production. Deletion of miR-155 in the stroma of RBPJ(-/-) mice prevented the development of myeloproliferative-like disease and cytokine induction. Analysis of BM from patients carrying myeloproliferative neoplasia also revealed elevated expression of miR-155. Thus, the Notch/miR-155/κB-Ras1/NF-κB axis regulates the inflammatory state of the BM niche and affects the development of myeloproliferative disorders

The InterHourly-Variability (IHV) Index of Geomagnetic Activity and its Use in Deriving the Long-term Variation of Solar Wind Speed

We describe the derivation of the InterHourly Variability (IHV) index of geomagnetic activity. The IHV-index for a geomagnetic element is mechanically derived from hourly values as the sum of the unsigned differences between adjacent hours over a seven-hour interval centered on local midnight. The index is derived separately for stations in both hemispheres within six longitude sectors using only local night hours. It is intended as a long-term index. Available data allows derivation of the index back well into the 19th century. On a time scale of a 27-day Bartels rotation, IHV averages for stations with corrected geomagnetic latitude less than 55 degrees are strongly correlated with midlatitude range indices. Assuming a constant calibration of the aa-index we find that observed yearly values of aa before the year 1957 are 2.9 nT too small compared to values calculated from IHV using the regression constants based on 1980-2004. We interpret this discrepancy as an indication that the calibration of the aa index is in error before 1957. There is no such problem with the ap index. Rotation averages of IHV are also strongly correlated with solar wind parameters (BV^2). On a time scale of a year combining the IHV-index and the recently-developed Inter-Diurnal Variability (IDV) index (giving B) allows determination of solar wind speed, V, from 1890-present. Over the ~120-year series, the yearly mean solar wind speed varied from a low of 303 km/s in 1902 to a high value of 545 km/s in 2003. The calculated yearly values of the product BV using B and V separately derived from IDV and IHV agree quantitatively with (completely independent) BV derived from the amplitude of the diurnal variation of the H component in the polar caps since 1926 and sporadically beyond

A high-throughput screen against pantothenate synthetase (PanC) identifies 3-biphenyl-4-cyanopyrrole-2-carboxylic acids as a new class of inhibitor with activity against Mycobacterium tuberculosis

The enzyme pantothenate synthetase, PanC, is an attractive drug target in Mycobacterium tuberculosis . It is essential for the in vitro growth of M. tuberculosis and for survival of the bacteria in the mouse model of infection. PanC is absent from mammals. We developed an enzyme-based assay to identify inhibitors of PanC, optimized it for high-throughput screening, and tested a large and diverse library of compounds for activity. Two compounds belonging to the same chemical class of 3-biphenyl-4- cyanopyrrole-2-carboxylic acids had activity against the purified recombinant protein, and also inhibited growth of live M. tuberculosis in manner consistent with PanC inhibition. Thus we have identified a new class of PanC inhibitors with whole cell activity that can be further developed