158 research outputs found

    Labor Mobility and the Problems of Modern Policing

    Get PDF
    We document and discuss the implications of a striking feature of modern American policing: the stasis of police labor forces. Using an original employment dataset assembled through public records requests, we show that, after the first few years on a job, officers rarely change employers, and intermediate officer ranks are filled almost exclusively through promotion rather than lateral hiring. Policing is like a sports league, if you removed trades and free agency and left only the draft in place. We identify both nonlegal and legal causes of this phenomenon—ranging from geographic monopolies to statutory and collectively bargained rules about pensions, rank, and seniority—and discuss its normative implications. On the one hand, job stability may encourage investment in training and expertise by agencies and officers alike; it may also attract some high-quality candidates, including candidates from underrepresented backgrounds, to the profession. On the other hand, low labor mobility can foster sclerosis in police departments, entrenching old ways of policing. Limited outside options may lead officers to stay in positions that suit them poorly, decreasing morale and productivity and potentially contributing to the scale of policing harms. In turn, the lack of labor mobility makes it all the more important to police officers to retain the jobs they have. This encourages them to insist on extensive labor protections and to enforce norms like the “blue wall of silence,” which exacerbate the problem of police misconduct. We suggest reforms designed to confer the advantages of labor mobility while ameliorating its costs

    Labor Mobility and the Problems of Modern Policing

    Get PDF
    We document and discuss the implications of a striking feature of modern American policing: the stasis of police labor forces. Using an original employment dataset assembled through public records requests, we show that, after the first few years on a job, officers rarely change employers, and intermediate officer ranks are filled almost exclusively through promotion rather than lateral hiring. Policing is like a sports league, if you removed trades and free agency and left only the draft in place. We identify both nonlegal and legal causes of this phenomenon—ranging from geographic monopolies to statutory and collectively bargained rules about pensions, rank, and seniority—and discuss its normative implications. On the one hand, job stability may encourage investment in training and expertise by agencies and officers alike; it may also attract some high-quality candidates, including candidates from underrepresented backgrounds, to the profession. On the other hand, low labor mobility can foster sclerosis in police departments, entrenching old ways of policing. Limited outside options may lead officers to stay in positions that suit them poorly, decreasing morale and productivity and potentially contributing to the scale of policing harms. In turn, the lack of labor mobility makes it all the more important to police officers to retain the jobs they have. This encourages them to insist on extensive labor protections and to enforce norms like the “blue wall of silence,” which exacerbate the problem of police misconduct. We suggest reforms designed to confer the advantages of labor mobility while ameliorating its costs

    APC-β-catenin-TCF signaling silences the intestinal guanylin-GUCY2C tumor suppressor axis.

    Get PDF
    Sporadic colorectal cancer initiates with mutations in APC or its degradation target β-catenin, producing TCF-dependent nuclear transcription driving tumorigenesis. The intestinal epithelial receptor, GUCY2C, with its canonical paracrine hormone guanylin, regulates homeostatic signaling along the crypt-surface axis opposing tumorigenesis. Here, we reveal that expression of the guanylin hormone, but not the GUCY2C receptor, is lost at the earliest stages of transformation in APC-dependent tumors in humans and mice. Hormone loss, which silences GUCY2C signaling, reflects transcriptional repression mediated by mutant APC-β-catenin-TCF programs in the nucleus. These studies support a pathophysiological model of intestinal tumorigenesis in which mutant APC-β-catenin-TCF transcriptional regulation eliminates guanylin expression at tumor initiation, silencing GUCY2C signaling which, in turn, dysregulates intestinal homeostatic mechanisms contributing to tumor progression. They expand the mechanistic paradigm for colorectal cancer from a disease of irreversible mutations in APC and β-catenin to one of guanylin hormone loss whose replacement, and reconstitution of GUCY2C signaling, could prevent tumorigenesis

    The next generation of target capture technologies - large DNA fragment enrichment and sequencing determines regional genomic variation of high complexity

    Get PDF
    Abstract Background The ability to capture and sequence large contiguous DNA fragments represents a significant advancement towards the comprehensive characterization of complex genomic regions. While emerging sequencing platforms are capable of producing several kilobases-long reads, the fragment sizes generated by current DNA target enrichment technologies remain a limiting factor, producing DNA fragments generally shorter than 1 kbp. The DNA enrichment methodology described herein, Region-Specific Extraction (RSE), produces DNA segments in excess of 20 kbp in length. Coupling this enrichment method to appropriate sequencing platforms will significantly enhance the ability to generate complete and accurate sequence characterization of any genomic region without the need for reference-based assembly. Results RSE is a long-range DNA target capture methodology that relies on the specific hybridization of short (20-25 base) oligonucleotide primers to selected sequence motifs within the DNA target region. These capture primers are then enzymatically extended on the 3’-end, incorporating biotinylated nucleotides into the DNA. Streptavidin-coated beads are subsequently used to pull-down the original, long DNA template molecules via the newly synthesized, biotinylated DNA that is bound to them. We demonstrate the accuracy, simplicity and utility of the RSE method by capturing and sequencing a 4 Mbp stretch of the major histocompatibility complex (MHC). Our results show an average depth of coverage of 164X for the entire MHC. This depth of coverage contributes significantly to a 99.94 % total coverage of the targeted region and to an accuracy that is over 99.99 %. Conclusions RSE represents a cost-effective target enrichment method capable of producing sequencing templates in excess of 20 kbp in length. The utility of our method has been proven to generate superior coverage across the MHC as compared to other commercially available methodologies, with the added advantage of producing longer sequencing templates amenable to DNA sequencing on recently developed platforms. Although our demonstration of the method does not utilize these DNA sequencing platforms directly, our results indicate that the capture of long DNA fragments produce superior coverage of the targeted region

    Theory of Chiral Modulations and Fluctuations in Smectic-A Liquid Crystals Under an Electric Field

    Full text link
    Chiral liquid crystals often exhibit periodic modulations in the molecular director; in particular, thin films of the smectic-C* phase show a chiral striped texture. Here, we investigate whether similar chiral modulations can occur in the induced molecular tilt of the smectic-A phase under an applied electric field. Using both continuum elastic theory and lattice simulations, we find that the state of uniform induced tilt can become unstable when the system approaches the smectic-A--smectic-C* transition, or when a high electric field is applied. Beyond that instability point, the system develops chiral stripes in the tilt, which induce corresponding ripples in the smectic layers. The modulation persists up to an upper critical electric field and then disappears. Furthermore, even in the uniform state, the system shows chiral fluctuations, including both incipient chiral stripes and localized chiral vortices. We compare these predictions with observed chiral modulations and fluctuations in smectic-A liquid crystals.Comment: 11 pages, including 9 postscript figures, uses REVTeX 3.0 and epsf.st

    The Tides of Titan

    Get PDF
    We have detected in Cassini spacecraft data the signature of the periodic tidal stresses within Titan, driven by the eccentricity (e = 0.028) of its 16-day orbit around Saturn. Precise measurements of the acceleration of Cassini during six close flybys between 2006 and 2011 have revealed that Titan responds to the variable tidal field exerted by Saturn with periodic changes of its quadrupole gravity, at about 4% of the static value. Two independent determinations of the corresponding degree-2 Love number yield k_2 = 0.589 ± 0.150 and k2 = 0.637 ± 0.224 (2σ). Such a large response to the tidal field requires that Titan’s interior be deformable over time scales of the orbital period, in a way that is consistent with a global ocean at depth

    Kepler eclipsing binary stars. VII. the catalogue of eclipsing binaries found in the entire Kepler data set

    Get PDF
    The primary Kepler Mission provided nearly continuous monitoring of ~200,000 objects with unprecedented photometric precision. We present the final catalog of eclipsing binary systems within the 105 deg2 Kepler field of view. This release incorporates the full extent of the data from the primary mission (Q0-Q17 Data Release). As a result, new systems have been added, additional false positives have been removed, ephemerides and principal parameters have been recomputed, classifications have been revised to rely on analytical models, and eclipse timing variations have been computed for each system. We identify several classes of systems including those that exhibit tertiary eclipse events, systems that show clear evidence of additional bodies, heartbeat systems, systems with changing eclipse depths, and systems exhibiting only one eclipse event over the duration of the mission. We have updated the period and galactic latitude distribution diagrams and included a catalog completeness evaluation. The total number of identified eclipsing and ellipsoidal binary systems in the Kepler field of view has increased to 2878, 1.3% of all observed Kepler targets
    corecore