An Atom Laser is not monochromatic

We study both numerically and analytically the possibility of using an adiabatic passage control method to construct a Mach-Zehnder interferometer (MZI) for Bose-Einstein condensates (BECs) in the time domain, in exact one-to-one correspondence with the traditional optical MZI that involves two beam splitters and two mirrors. The interference fringes one obtains from such a minimum-disturbance set up clearly demonstrates that, fundamentally, an atom laser is not monochromatic due to interatomic interactions. We also consider how the amount of entanglement in the system correlates to the interference fringes.Comment: 4 figures. Submitted for publicatio

Why are Buyouts Levered: The Financial Structure of Private Equity Funds

This paper presents a model of the financial structure of private equity firms. In the model, the general partner of the firm encounters a sequence of deals over time where the exact quality of each deal cannot be credibly communicated to investors. We show that the optimal financing arrangement is consistent with a number of characteristics of the private equity industry. First, the firm should be financed by a combination of fund capital raised before deals are encountered, and capital that is raised to finance a specific deal. Second, the fund investors' claim on fund cash flow is a combination of debt and levered equity, while the general partner receives a claim similar to the carry contracts received by real-world practitioners. Third, the fund will be set up in a manner similar to that observed in practice, with investments pooled within a fund, decision rights over investments held by the general partner, and limits set in partnership agreements on the size of particular investments. Fourth, the model suggests that incentives will lead to overinvestment in good states of the world and underinvestment in bad states, so that the natural industry cycles will be multiplied. Fifth, investments made in recessions will on average outperform investments made in booms.

Some Problems in Minnesota Chippewa Acculturation

The Indian Problem is a term frequently used without precise definition. It serves, perhaps, to bring to the mind of the general public conditions of poverty, backwardness, drunkenness, disrespect for the law, and lack of education and community organization among the Indians. An objection to this approach is that it does not provide adequate or systematic understanding of the basic nature of this problem, but refers rather to the easily observable external manifestations. The Indian Problem approach also seems to attribute to all Indians an inherent tendency toward socially unacceptable behavior. A more profitable approach is to identify some of the causes for the overt social disorganization by examining the cultural traditions of the Chippewa and their historical relations with the dominant white society

Application of multispectral radar and LANDSAT imagery to geologic mapping in death valley

Side-Looking Airborne Radar (SLAR) images, acquired by JPL and Strategic Air Command Systems, and visible and near-infrared LANDSAT imagery were applied to studies of the Quaternary alluvial and evaporite deposits in Death Valley, California. Unprocessed radar imagery revealed considerable variation in microwave backscatter, generally correlated with surface roughness. For Death Valley, LANDSAT imagery is of limited value in discriminating the Quaternary units except for alluvial units distinguishable by presence or absence of desert varnish or evaporite units whose extremely rough surfaces are strongly shadowed. In contrast, radar returns are most strongly dependent on surface roughness, a property more strongly correlated with surficial geology than is surface chemistry

The Origin of the External Basins of the Betics, Southern Spain, and Their Use in Interpreting the Orogenic History

The Betic mountain chain of Southern Spain, together with the Rif Mountains of N.W. Africa forms the western-most extension of the Alpine mountain chain in Europe. The Orogen formed as a direct result of the interaction between the African and Iberian plates which took place from the late Cretaceous onwards. The origin of the Betics is far from understood and there are several conflicting hypotheses concerning the origin of the Orogen. There are two major external basins to the Betic Orogen in Southern Spain, the Guadalquivir Basin and the Gibraltar Arc Flysch, and both provide important insights into its tectonic history. The Guadalquivir Basin lies on the northern margin of the External Zone Tertiary fold-thrust belt of the Betic Orogen and south of the Palaeozoic Iberian Meseta. It can be subdivided into structurally distinct regions, an undeformed autochthonous basin which lies to the north of a deformed allochthonous basin. The origin of the Guadalquivir Basin (previously interpreted as being the foreland basin to the Orogen) is questioned. Structured sedimentological and provenance studies demonstrate that the Guadalquivir Basin is not a foreland basin because; 1. It formed as an integral part of the destruction of the Iberian passive margin during which time thin skinned thrusting generated a basin on the northern margin of the External Zones, 2. The fill and unconformities of this basin were controlled by eustasy rather by the tectonic incursion of an orogenic wedge being driven onto the Iberian Margin, 3. The basin did not form by the downward flexure of the lithosphere in response to an orogenic load. Therefore the basin cannot be considered to be a true foreland basin. The clastic sedimentation in the Guadalquivir Basin was controlled by the emergence of the External Zone thrust sheet, during the late Miocene, which was related to the thin skinned thrusting. During this time the recycling of material, that had originally been derived from the Palaeozoic Iberian Meseta. took place. A thrusting event at the the end of the Miocene/ early Pliocene led to the destruction of the Guadalquivir Basin which was subdivided into the allochthon and autochthon seen today. The Gibraltar Arc flysch nappes link the External Rif of North Africa to the External Zone of Southern Spain. The largest unit of the Gibraltar Arc is the Aljibe Flysch which can be subdivided into the Beneiza Flysch and Aljibe Arenites, which are Oligo-Miocene in age. The Beneiza Flysch is characterised by thin sandstones and siltstones that are interpreted to have been deposited by turbiditic currents. These pass rapidly upwards into the thick bedded and super-mature Aljibe Arenites, which are entirely dominated by water escape- structures. The contact between these two units marks a dramatic change in the depositional environment at the beginning of the Miocene. The Aljibe Flysch is interpreted as recording the development of a basin plain that became tectonically segregated at the beginning of the Miocene, at which time new and tectonically confined basins developed. Tectonic instabilities created elsewhere in the External Zone resulted in mobilisation of large amounts of sediment which was rapidly deposited in the newly created basins. The flysch units have subsequently been thrust westwards post-Lower Miocene during which time peridotites were emplaced into mid-crustal levels Consideration of the tectonic and sedimentary history of the Guadalquivir Basin and Gibraltar Arc Flysch provides an important insight into the tectonic history of the Betic Orogen. Data collected during the study of these basins, combined with important new published data from the Alboran Sea and Ronda Peridotites, has resulted in the rejection of the widely accepted 'extensional collapse' model and in the identification of strike-slip tectonism and transcurrent movements as the main mechanism for the building of the Betic Orogen. Miocene transcurrent movements in the Betic area resulted in the break up the Iberian passive margin, the emplacement of metamorphic terranes and in the formation of thrusts in the Gibraltar Arc through a complicated history of transtension and transpression in the region of the Alboran sea

Molecular Events in the Cell Types of the Olfactory Epithelium during Adult Neurogenesis

BACKGROUND: Adult neurogenesis, fundamental for cellular homeostasis in the mammalian olfactory epithelium, requires major shifts in gene expression to produce mature olfactory sensory neurons (OSNs) from multipotent progenitor cells. To understand these dynamic events requires identifying not only the genes involved but also the cell types that express each gene. Only then can the interrelationships of the encoded proteins reveal the sequences of molecular events that control the plasticity of the adult olfactory epithelium. RESULTS: Of 4,057 differentially abundant mRNAs at 5 days after lesion-induced OSN replacement in adult mice, 2,334 were decreased mRNAs expressed by mature OSNs. Of the 1,723 increased mRNAs, many were expressed by cell types other than OSNs and encoded proteins involved in cell proliferation and transcriptional regulation, consistent with increased basal cell proliferation. Others encoded fatty acid metabolism and lysosomal proteins expressed by infiltrating macrophages that help scavenge debris from the apoptosis of mature OSNs. The mRNAs of immature OSNs behaved dichotomously, increasing if they supported early events in OSN differentiation (axon initiation, vesicular trafficking, cytoskeletal organization and focal adhesions) but decreasing if they supported homeostatic processes that carry over into mature OSNs (energy production, axon maintenance and protein catabolism). The complexity of shifts in gene expression responsible for converting basal cells into neurons was evident in the increased abundance of 203 transcriptional regulators expressed by basal cells and immature OSNs. CONCLUSIONS: Many of the molecular changes evoked during adult neurogenesis can now be ascribed to specific cellular events in the OSN cell lineage, thereby defining new stages in the development of these neurons. Most notably, the patterns of gene expression in immature OSNs changed in a characteristic fashion as these neurons differentiated. Initial patterns were consistent with the transition into a neuronal morphology (neuritogenesis) and later patterns with neuronal homeostasis. Overall, gene expression patterns during adult olfactory neurogenesis showed substantial similarity to those of embryonic brain

Genomics of Mature and Immature Olfactory Sensory Neurons

The continuous replacement of neurons in the olfactory epithelium provides an advantageous model for investigating neuronal differentiation and maturation. By calculating the relative enrichment of every mRNA detected in samples of mature mouse olfactory sensory neurons (OSNs), immature OSNs, and the residual population of neighboring cell types, and then comparing these ratios against the known expression patterns of \u3e300 genes, enrichment criteria that accurately predicted the OSN expression patterns of nearly all genes were determined. We identified 847 immature OSN-specific and 691 mature OSN-specific genes. The control of gene expression by chromatin modification and transcription factors, and neurite growth, protein transport, RNA processing, cholesterol biosynthesis, and apoptosis via death domain receptors, were overrepresented biological processes in immature OSNs. Ion transport (ion channels), presynaptic functions, and cilia-specific processes were overrepresented in mature OSNs. Processes overrepresented among the genes expressed by all OSNs were protein and ion transport, ER overload response, protein catabolism, and the electron transport chain. To more accurately represent gradations in mRNA abundance and identify all genes expressed in each cell type, classification methods were used to produce probabilities of expression in each cell type for every gene. These probabilities, which identified 9,300 genes expressed in OSNs, were 96% accurate at identifying genes expressed in OSNs and 86% accurate at discriminating genes specific to mature and immature OSNs. This OSN gene database not only predicts the genes responsible for the major biological processes active in OSNs, but also identifies thousands of never before studied genes that support OSN phenotypes

Biofilm and Cell Adhesion Strength on Dental Implant Surfaces via the Laser Spallation Technique

OBJECTIVE: The aims of this study are to quantify the adhesion strength differential between an oral bacterial biofilm and an osteoblast-like cell monolayer to a dental implant-simulant surface and develop a metric that quantifies the biocompatible effect of implant surfaces on bacterial and cell adhesion. METHODS: High-amplitude short-duration stress waves generated by laser pulse absorption are used to spall bacteria and cells from titanium substrates. By carefully controlling laser fluence and calibration of laser fluence with applied stress, the adhesion difference between Streptococcus mutans biofilms and MG 63 osteoblast-like cell monolayers on smooth and rough titanium substrates is obtained. The ratio of cell adhesion strength to biofilm adhesion strength (i.e., Adhesion Index) is determined as a nondimensionalized parameter for biocompatibility assessment. RESULTS: Adhesion strength of 143 MPa, with a 95% C.I. (114, 176), is measured for MG 63 cells on smooth titanium and 292 MPa, with a 95% C.I. (267, 306), on roughened titanium. Adhesion strength for S. mutans on smooth titanium is 320 MPa, with a 95% C.I. (304, 333), and remained relatively constant at 332 MPa, with a 95% C.I. (324, 343), on roughened titanium. The calculated Adhesion Index for smooth titanium is 0.451, with a 95% C.I. (0.267, 0.622), which increased to 0.876, with a 95% C.I. (0.780, 0.932), on roughened titanium. SIGNIFICANCE: The laser spallation technique provides a platform to examine the tradeoffs of adhesion modulators on both biofilm and cell adhesion. This tradeoff is characterized by the Adhesion Index, which is proposed to aid biocompatibility screening and could help improve implantation outcomes. The Adhesion Index is implemented to determine surface factors that promote favorable adhesion of cells greater than biofilms. Here, an Adhesion Index ≫ 1 suggests favorable biocompatibility