Searches for massive neutrinos with mechanical quantum sensors

The development of quantum optomechanics now allows mechanical sensors with femtogram masses to be controlled and measured in the quantum regime. If the mechanical element contains isotopes that undergo nuclear decay, measuring the recoil of the sensor following the decay allows reconstruction of the total momentum of all emitted particles, including any neutral particles that may escape detection in traditional detectors. As an example, for weak nuclear decays the momentum of the emitted neutrino can be reconstructed on an event-by-event basis. We present the concept that a single nanometer-scale, optically levitated sensor operated with sensitivity near the standard quantum limit can search for heavy sterile neutrinos in the keV-MeV mass range with sensitivity significantly beyond existing constraints. We also comment on the possibility that mechanical sensors operated well into the quantum regime might ultimately reach the sensitivities required to provide an absolute measurement of the mass of the light neutrino states.Comment: 11 pages + refs, 7 figures. v2: published version (+ an appendix containing a quantum model of the 3-body decay in a nanosphere

Ancient water supports today's energy needs

The water footprint for fossil fuels typically accounts for water utilized in mining and fuel processing, whereas the water footprint of biofuels assesses the agricultural water used by crops through their lifetime. Fossil fuels have an additional water footprint that is not easily accounted for: ancient water that was used by plants millions of years ago, before they were transformed into fossil fuel. How much water is mankind using from the past to sustain current energy needs? We evaluate the link between ancient water virtually embodied in fossil fuels to current global energy demands by determining the water demand required to replace fossil fuels with biomass produced with water from the present. Using equal energy units of wood, bioethanol, and biodiesel to replace coal, natural gas, and crude oil, respectively, the resulting water demand is 7.39 × 1013 m3 y−1, approximately the same as the total annual evaporation from all land masses and transpiration from all terrestrial vegetation. Thus, there are strong hydrologic constraints to a reliance on biofuel energy produced with water from the present because the conversion from fossil fuels to biofuels would have a disproportionate and unsustainable impact on the modern water. By using fossil fuels to meet today's energy needs, we are virtually using water from a geological past. The water cycle is insufficient to sustain the production of the fuel presently consumed by human societies. Thus, non‐fuel‐based renewable energy sources are needed to decrease mankind's reliance on fossil fuel energy without placing an overwhelming pressure on global freshwater resources

Software systems for operation, control, and monitoring of the EBEX instrument

We present the hardware and software systems implementing autonomous operation, distributed real-time monitoring, and control for the EBEX instrument. EBEX is a NASA-funded balloon-borne microwave polarimeter designed for a 14 day Antarctic flight that circumnavigates the pole. To meet its science goals the EBEX instrument autonomously executes several tasks in parallel: it collects attitude data and maintains pointing control in order to adhere to an observing schedule; tunes and operates up to 1920 TES bolometers and 120 SQUID amplifiers controlled by as many as 30 embedded computers; coordinates and dispatches jobs across an onboard computer network to manage this detector readout system; logs over 3~GiB/hour of science and housekeeping data to an onboard disk storage array; responds to a variety of commands and exogenous events; and downlinks multiple heterogeneous data streams representing a selected subset of the total logged data. Most of the systems implementing these functions have been tested during a recent engineering flight of the payload, and have proven to meet the target requirements. The EBEX ground segment couples uplink and downlink hardware to a client-server software stack, enabling real-time monitoring and command responsibility to be distributed across the public internet or other standard computer networks. Using the emerging dirfile standard as a uniform intermediate data format, a variety of front end programs provide access to different components and views of the downlinked data products. This distributed architecture was demonstrated operating across multiple widely dispersed sites prior to and during the EBEX engineering flight.Comment: 11 pages, to appear in Proceedings of SPIE Astronomical Telescopes and Instrumentation 2010; adjusted metadata for arXiv submissio

EBEX: A balloon-borne CMB polarization experiment

EBEX is a NASA-funded balloon-borne experiment designed to measure the polarization of the cosmic microwave background (CMB). Observations will be made using 1432 transition edge sensor (TES) bolometric detectors read out with frequency multiplexed SQuIDs. EBEX will observe in three frequency bands centered at 150, 250, and 410 GHz, with 768, 384, and 280 detectors in each band, respectively. This broad frequency coverage is designed to provide valuable information about polarized foreground signals from dust. The polarized sky signals will be modulated with an achromatic half wave plate (AHWP) rotating on a superconducting magnetic bearing (SMB) and analyzed with a fixed wire grid polarizer. EBEX will observe a patch covering ~1% of the sky with 8' resolution, allowing for observation of the angular power spectrum from \ell = 20 to 1000. This will allow EBEX to search for both the primordial B-mode signal predicted by inflation and the anticipated lensing B-mode signal. Calculations to predict EBEX constraints on r using expected noise levels show that, for a likelihood centered around zero and with negligible foregrounds, 99% of the area falls below r = 0.035. This value increases by a factor of 1.6 after a process of foreground subtraction. This estimate does not include systematic uncertainties. An engineering flight was launched in June, 2009, from Ft. Sumner, NM, and the long duration science flight in Antarctica is planned for 2011. These proceedings describe the EBEX instrument and the North American engineering flight.Comment: 12 pages, 9 figures, Conference proceedings for SPIE Millimeter, Submillimeter, and Far-Infrared Detectors and Instrumentation for Astronomy V (2010

Scenario planning: the future of the cattle and sheep industries in Scotland and their resiliency to disease

In this paper, we present a description of foresighting activities undertaken by EPIC, Scotland’s Centre of Expertise on Animal Disease Outbreaks, to investigate the future uncertainty of animal health security in the Scottish sheep and cattle sectors. Using scenario planning methodologies, we explored four plausible but provocative long-term futures which identify dynamics underpinning the resilience of these agricultural sectors to animal disease. These scenarios highlight a number of important drivers that influence disease resilience: industry demographics, the role of government support and regulation and the capacity for technological innovation to support the industry to meet local and global market demand. Participants in the scenario planning exercises proposed creative, robust strategies that policy makers could consider implementing now to enhance disease control and industry resilience in multiple, uncertain futures. Using these participant-led strategies as a starting point, we offer ten key questions for policy makers and stakeholders to provoke further discussion about improving resiliency and disease preparedness. We conclude with a brief discussion of the value of scenario planning, not only for the development of futures which will inform disease contingency plans and improve industry resilience, but as a mechanism for dialogue and information sharing between stakeholders and government

US Cosmic Visions: New Ideas in Dark Matter 2017: Community Report

This white paper summarizes the workshop "U.S. Cosmic Visions: New Ideas in Dark Matter" held at University of Maryland on March 23-25, 2017.Comment: 102 pages + reference

Protein Design Using Continuous Rotamers

Optimizing amino acid conformation and identity is a central problem in computational protein design. Protein design algorithms must allow realistic protein flexibility to occur during this optimization, or they may fail to find the best sequence with the lowest energy. Most design algorithms implement side-chain flexibility by allowing the side chains to move between a small set of discrete, low-energy states, which we call rigid rotamers. In this work we show that allowing continuous side-chain flexibility (which we call continuous rotamers) greatly improves protein flexibility modeling. We present a large-scale study that compares the sequences and best energy conformations in 69 protein-core redesigns using a rigid-rotamer model versus a continuous-rotamer model. We show that in nearly all of our redesigns the sequence found by the continuous-rotamer model is different and has a lower energy than the one found by the rigid-rotamer model. Moreover, the sequences found by the continuous-rotamer model are more similar to the native sequences. We then show that the seemingly easy solution of sampling more rigid rotamers within the continuous region is not a practical alternative to a continuous-rotamer model: at computationally feasible resolutions, using more rigid rotamers was never better than a continuous-rotamer model and almost always resulted in higher energies. Finally, we present a new protein design algorithm based on the dead-end elimination (DEE) algorithm, which we call iMinDEE, that makes the use of continuous rotamers feasible in larger systems. iMinDEE guarantees finding the optimal answer while pruning the search space with close to the same efficiency of DEE. Availability: Software is available under the Lesser GNU Public License v3. Contact the authors for source code

Perceptions About Work/Life Balance Among DU Community Members with Young Children

Background: In the past fifty years, families in the USA have changed in configuration, size and dynamics. The percentage of families that do not conform to the traditional family unit (married mother and father with children) has increased as there are more single-parent families, LGBTQ families and interracial families. The proportion of unmarried or divorced families has also increased, as it has the number of married and unmarried couples that opt to not have children and, additionally, more couples are opting for adoption and foster parenting (Pew Research Center 2010). Furthermore, the percentage of households where all the adults work has increased, which impacts the amount and quality of time available for family activities and household chores (Bianchi, Robinson and Milkie 2006). These and other trends have led to the identification of “work-family balance” as an important challenge of our times, one that families have been facing for decades and that institutions are only starting to pay attention to (Hochschild 2013). Although there are many aspects of family life that are challenging to balance with workplace demands, childcare has been specifically identified as one that needs attention (Desilver 2014). Methods: Study goal: To describe the perceptions that some DU community members with children have about work-family balance with attention to challenges, difficulties and institutional responses. Study design: Descriptive, cross-sectional, qualitative study. Population and sample: We recruited 63 University of Denver students (13), staff (14) and faculty (36) who are responsible of parenting at least one child under 10 years of age. We used purposive sampling. which consists in actively finding individuals who meet the criteria. Data collection: Semi structured interviews (January 23-February 8, 2017), in person, audio recorded and transcribed within one week. Participants’ autonomy, confidentiality and anonymity were protected throughout the process. Data analysis: Thematic analysis, which consists in the systematic identification of themes in the interview transcripts, followed by their conceptual organization and hierarchization. Research team: sixty-six undergraduate students taking Cultural Anthropology (ANTH 2010) in winter 2017, four graduate teaching assistants and one course instructor. Findings: Student participants portrayed work/life balance as set of interconnected situations and relations that go from the deeply personal to the interpersonal, communal and institutional. Aiming at capturing such complexity, we organized our findings in four themes: work/life balance, family dynamics, personal challenges and support. Participants told us about their struggles when negotiating work and life responsibilities which often lead to feelings of guilt, which are mediated by their colleagues’ reactions, schedule flexibility, their job situation and the presence or absence of maternity leave. Family dynamics reflected a tension between a narrative of independence and one of dependence in raising children, highlighting the importance of social networks, both of which are also affected by immigration status and intra-household negotiations particularly, Perceptions about work/life balance among DU community members with young children Cultural Anthropology (ANTH 2010) winter 2017 4 with their partners. Personal challenges relate primarily with time management and establishing clear boundaries between work and family, which related to managing emails, organization and scheduling of activities, maintaining a financial balance, and solving transportation needs, all of which were mediated the ability parents have of controlling a flexible work schedule, an ability greatly diminished among students. Support parents need related to child care goes from the one that happens in interpersonal interactions with neighbors, friends, relatives and colleagues, to the institutionalized forms of support, where participants expressed their frustration for the insufficiency of accessible options in Denver, the lack of options at DU, and the inaccessibility of DU’s Fisher Early Learning Center. Conclusions and recommendations: Participant’s ability to control their schedules together with their financial and social capital seem to shape important differences in the ability that parents have for balancing work and life. Students, single parents and recent immigrants seem to have a combination of elements that add to the challenges. At the interpersonal level, simple acts of kindness, sympathy and empathy in the everyday interactions seem to make an important difference to parents. The perception that many of the student participants expressed about the academy not being comfortable with children, families or parents could be addressed by making it normal to talk about all these aspects of life. At the institutional level, efforts could be made at reaching out to parents, especially students and single parents, to offer them guidance and support that is already in place at DU, such as counselling and wellbeing resources, as well as orientation related to institutional policies. Policies related to maternity and paternity leave should be refined to ensure that they do not negatively affect those they are supposed to support. Convenient, affordable and sustainable on-campus child care options should be seriously considered given that they would enhance the possibilities for parents to participate in activities at DU. Events should be organized where members of the DU community have the opportunity to share not as students, staff or faculty, but as members of families

Computational Design of a PDZ Domain Peptide Inhibitor that Rescues CFTR Activity

The cystic fibrosis transmembrane conductance regulator (CFTR) is an epithelial chloride channel mutated in patients with cystic fibrosis (CF). The most prevalent CFTR mutation, ΔF508, blocks folding in the endoplasmic reticulum. Recent work has shown that some ΔF508-CFTR channel activity can be recovered by pharmaceutical modulators (“potentiators” and “correctors”), but ΔF508-CFTR can still be rapidly degraded via a lysosomal pathway involving the CFTR-associated ligand (CAL), which binds CFTR via a PDZ interaction domain. We present a study that goes from theory, to new structure-based computational design algorithms, to computational predictions, to biochemical testing and ultimately to epithelial-cell validation of novel, effective CAL PDZ inhibitors (called “stabilizers”) that rescue ΔF508-CFTR activity. To design the “stabilizers”, we extended our structural ensemble-based computational protein redesign algorithm to encompass protein-protein and protein-peptide interactions. The computational predictions achieved high accuracy: all of the top-predicted peptide inhibitors bound well to CAL. Furthermore, when compared to state-of-the-art CAL inhibitors, our design methodology achieved higher affinity and increased binding efficiency. The designed inhibitor with the highest affinity for CAL (kCAL01) binds six-fold more tightly than the previous best hexamer (iCAL35), and 170-fold more tightly than the CFTR C-terminus. We show that kCAL01 has physiological activity and can rescue chloride efflux in CF patient-derived airway epithelial cells. Since stabilizers address a different cellular CF defect from potentiators and correctors, our inhibitors provide an additional therapeutic pathway that can be used in conjunction with current methods