Equal, equitable, or optimal : a comparative analysis of the regional policies and financial structures impacting residential solar adoption

Diversification of energy production is increasingly important as concerns over emissions, energy independence and fuel costs emerge. As such, policies and incentive structures have been put in place by both federal and local government to increase solar energy generation. Since solar energy generation is not confined to utility or commercial scale projects it is feasible for households to become small generators and for local utilities to encourage or discourage residential energy production. While the cost of solar has been decreasing, installing residential solar PV is still a capital-intensive venture. The impact of residential solar has been debated but the presence of federal tax credits, increasing renewable energy requirements, and reduced emission standards signify that it is a subject cities and utilities must contend with. The Texas cities of Austin, San Antonio, and Georgetown represent three case studies of different programs, policies and financial approaches towards residential solar PV. The findings suggest that most average 20-year residential solar PV projects are net positive for homeowners. 10-year projects in cities that offer up-front rebates, such as Austin and San Antonio, are more likely to save residents money on the investment over non-rebate cities like Georgetown. 10-year projects without the federal investment tax credit result in mostly net negative financial outcomes for residents. Each city has utilized a unique a model that can be classified as equal, equitable, or optimal. These models have varying impacts on residents, including consumer reasoning for installing solar and financial feasibility of the investment. Austin and San Antonio have stated goals of increasing renewable energy generation and include residential solar PV in the renewable expansion, because of this, the cities provide more assistance and programs for residents to participate in solar projects. Georgetown already has power purchase agreements in place to fully provide renewable energy to residents and as such are not as interested in incentivizing residential solar PV for the environmental effects.Energy and Earth ResourcesBusiness Administratio

Investment Spikes: New Facts and a General Equilibrium Exploration

Using plant-level data from Chile and the U.S. we show that investment spikes are highly pro-cyclical, so much so that changes in the number of establishments undergoing investment spikes (the "extensive margin") account for the bulk of variation in aggregate investment. The number of establishments undergoing investment spikes also has independent predictive power for aggregate investment, even controlling for past investment and sales. We re-calibrate the Thomas (2002) model (that includes fixed costs of investing) so that it assigns a prominent role to extensive adjustment. The recalibrated model has different properties than the standard RBC model for some shocks.

Adding Sweeteners to Softwood Lumber: The WTO-NAFTA “Spaghetti Bowl” Is Cooking

With the Doha round in trouble, the so-called spaghetti bowl of multilateral trade rules and proliferating regional trade deals, is, once again, prominently on the radar screen of the international trade community. Perfect examples of this image are the longstanding US-Canada softwood lumber and US-Mexico sweetener disputes. Both trade spats, extensively litigated in NAFTA and the WTO, are close to reaching a climax. Fueling the suspense is that the WTO and NAFTA may reach different results

Structural basis for dual roles of Aar2p in U5 snRNP assembly

Yeast U5 small nuclear ribonucleoprotein particle (snRNP) is assembled via a cytoplasmic precursor that contains the U5-specific Prp8 protein but lacks the U5-specific Brr2 helicase. Instead, pre-U5 snRNP includes the Aar2 protein not found in mature U5 snRNP or spliceosomes. Aar2p and Brr2p bind competitively to a C-terminal region of Prp8p that comprises consecutive RNase H-like and Jab1/MPN-like domains. To elucidate the molecular basis for this competition, we determined the crystal structure of Aar2p in complex with the Prp8p RNase H and Jab1/MPN domains. Aar2p binds on one side of the RNase H domain and extends its C terminus to the other side, where the Jab1/MPN domain is docked onto a composite Aar2p–RNase H platform. Known Brr2p interaction sites of the Jab1/MPN domain remain available, suggesting that Aar2p-mediated compaction of the Prp8p domains sterically interferes with Brr2p binding. Moreover, Aar2p occupies known RNA-binding sites of the RNase H domain, and Aar2p interferes with binding of U4/U6 di-snRNA to the Prp8p C-terminal region. Structural and functional analyses of phospho-mimetic mutations reveal how phosphorylation reduces affinity of Aar2p for Prp8p and allows Brr2p and U4/U6 binding. Our results show how Aar2p regulates both protein and RNA binding to Prp8p during U5 snRNP assembly

What's Blocking the Sun?: Solar Photovoltaics for the U.S. Commercial Market

Provides an overview of installation trends and investment climate for solar photovoltaics in the U.S. commercial sector, including policy and economic obstacles. Recommends strategies for the solar industry, the commercial sector, and policy makers

The dynamics and excitation of torsional waves in geodynamo simulations

The predominant force balance in rapidly rotating planetary cores is between Coriolis, pressure, buoyancy and Lorentz forces. This magnetostrophic balance leads to a Taylor state where the spatially averaged azimuthal Lorentz force is compelled to vanish on cylinders aligned with the rotation axis. Any deviation from this state leads to a torsional oscillation, signatures of which have been observed in the Earth's secular variation and are thought to influence length of day variations via angular momentum conservation. In order to investigate the dynamics of torsional oscillations (TOs), we perform several 3-D dynamo simulations in a spherical shell. We find TOs, identified by their propagation at the correct Alfvén speed, in many of our simulations. We find that the frequency, location and direction of propagation of the waves are influenced by the choice of parameters. Torsional waves are observed within the tangent cylinder and also have the ability to pass through it. Several of our simulations display waves with core traveltimes of 4–6 yr. We calculate the driving terms for these waves and find that both the Reynolds force and ageostrophic convection acting through the Lorentz force are important in driving TOs

Molecular principles underlying dual RNA specificity in the Drosophila SNF protein

The first RNA recognition motif of the Drosophila SNF protein is an example of an RNA binding protein with multi-specificity. It binds different RNA hairpin loops in spliceosomal U1 or U2 small nuclear RNAs, and only in the latter case requires the auxiliary U2A′ protein. Here we investigate its functions by crystal structures of SNF alone and bound to U1 stem-loop II, U2A′ or U2 stem-loop IV and U2A′, SNF dynamics from NMR spectroscopy, and structure-guided mutagenesis in binding studies. We find that different loop-closing base pairs and a nucleotide exchange at the tips of the loops contribute to differential SNF affinity for the RNAs. U2A′ immobilizes SNF and RNA residues to restore U2 stem-loop IV binding affinity, while U1 stem-loop II binding does not require such adjustments. Our findings show how U2A′ can modulate RNA specificity of SNF without changing SNF conformation or relying on direct RNA contacts

Trick or Heat? Manipulating Critical Temperature-Based Control Systems Using Rectification Attacks

Temperature sensing and control systems are widely used in the closed-loop control of critical processes such as maintaining the thermal stability of patients, or in alarm systems for detecting temperature-related hazards. However, the security of these systems has yet to be completely explored, leaving potential attack surfaces that can be exploited to take control over critical systems. In this paper we investigate the reliability of temperature-based control systems from a security and safety perspective. We show how unexpected consequences and safety risks can be induced by physical-level attacks on analog temperature sensing components. For instance, we demonstrate that an adversary could remotely manipulate the temperature sensor measurements of an infant incubator to cause potential safety issues, without tampering with the victim system or triggering automatic temperature alarms. This attack exploits the unintended rectification effect that can be induced in operational and instrumentation amplifiers to control the sensor output, tricking the internal control loop of the victim system to heat up or cool down. Furthermore, we show how the exploit of this hardware-level vulnerability could affect different classes of analog sensors that share similar signal conditioning processes. Our experimental results indicate that conventional defenses commonly deployed in these systems are not sufficient to mitigate the threat, so we propose a prototype design of a low-cost anomaly detector for critical applications to ensure the integrity of temperature sensor signals.Comment: Accepted at the ACM Conference on Computer and Communications Security (CCS), 201

Imaging regulatory T cell dynamics and CTLA4-mediated suppression of T cell priming

Foxp3(+) regulatory T cells (Tregs) maintain immune homoeostasis through mechanisms that remain incompletely defined. Here by two-photon (2P) imaging, we examine the cellular dynamics of endogenous Tregs. Tregs are identified as two non-overlapping populations in the T-zone and follicular regions of the lymph node (LN). In the T-zone, Tregs migrate more rapidly than conventional T cells (Tconv), extend longer processes and interact with resident dendritic cells (DC) and Tconv. Tregs intercept immigrant DCs and interact with antigen-induced DC: Tconv clusters, while continuing to form contacts with activated Tconv. During antigen-specific responses, blocking CTLA4-B7 interactions reduces Treg-Tconv interaction times, increases the volume of DC: Tconv clusters and enhances subsequent Tconv proliferation in vivo. Our results demonstrate a role for altered cellular choreography of Tregs through CTLA4-based interactions to limit T-cell priming