Spectroscopy of a synthetic trapped ion qubit

$^{133}\text{Ba}^+$ has been identified as an attractive ion for quantum information processing due to the unique combination of its spin-1/2 nucleus and visible wavelength electronic transitions. Using a microgram source of radioactive material, we trap and laser-cool the synthetic $A$ = 133 radioisotope of barium II in a radio-frequency ion trap. Using the same, single trapped atom, we measure the isotope shifts and hyperfine structure of the $6^2 \text{P}_{1/2}$ $\leftrightarrow$ $6^2 \text{S}_{1/2}$ and $6^2 \text{P}_{1/2}$ $\leftrightarrow$ $5^2 \text{D}_{3/2}$ electronic transitions that are needed for laser cooling, state preparation, and state detection of the clock-state hyperfine and optical qubits. We also report the $6^2 \text{P}_{1/2}$ $\leftrightarrow$ $5^2 \text{D}_{3/2}$ electronic transition isotope shift for the rare $A$ = 130 and 132 barium nuclides, completing the spectroscopic characterization necessary for laser cooling all long-lived barium II isotopes

Novel methodology for in situ carbon dioxide enrichment of benthic ecosystems

Future climate change will likely represent a major stress to shallow aquatic and coastal marine communities around the world. Most climate change research, particularly in regards to increased pCO2 and ocean acidification, relies on ex situ mesocosm experimentation, isolating target organisms from their environment. Such mesocosms allow for greater experimental control of some variables, but can often cause unrealistic changes in a variety of environmental factors, leading to “bottle effects.” Here we present an in situ technique of altering dissolved pCO2within nearshore benthic communities (e.g., macrophytes, algae, and/or corals) using submerged clear, open-top chambers. Our technique utilizes a flow-through design that replicates natural water flow conditions and minimizes caging effects. The clear, open-top design additionally ensures that adequate light reaches the benthic community. Our results show that CO2 concentrations and pH can be successfully manipulated for long durations within the open-top chambers, continuously replicating forecasts for the year 2100. Enriched chambers displayed an average 0.46 unit reduction in pH as compared with ambient chambers over a 6-month period. Additionally, CO2 and HCO3 – concentrations were all significantly higher within the enriched chambers. We discuss the advantages and disadvantages of this technique in comparison to other ex situ mesocosm designs used for climate change research

Interspecific variation in the elemental and stable isotope content of seagrasses in South Florida

The elemental (C, N, and P) and isotope (δ13C, δ15N) content of leaves of the seagrasses Thalassia testudinum, Halodule wrightii, and Syringodium filiforme were measured across a 10 000 km2 survey of the seagrass communities of South Florida, USA, in 1999 and 2000. Trends at local and broad spatial scales were compared to examine interspecific variation in the seagrass characteristics often used as ecological indicators. The elemental and stable isotope contents of all species were variable and demonstrated marked interspecific variation. At broad spatial scales, mean N:P ratios were lowest for T. testudinum (36.5 ± 1.1) and S. filiforme (38.9 ± 1.3), and highest for H. wrightii (44.1 ± 1.8). Stable carbon isotope ratios (δ13C) were highest for S. filiforme (–6.2 ± 0.2‰), intermediate for T. testudinum (–8.6 ± 0.2‰), and lowest for H. wrightii (–10.6 ± 0.3‰). Stable nitrogen isotopes (δ15N) were heaviest for T. testudinum (2.0 ± 0.1‰), and lightest for H. wrightii (1.0 ± 0.3‰) and S. filiforme (1.6 ± 0.2‰). Site depth was negatively correlated to δ13C for all species, while δ15N was positively correlated to depth for H. wrightii and S. filiforme. Similar trends were observed in local comparisons, suggesting that taxon-specific physiological/ecological properties strongly control interspecific variation in elemental and stable isotope content. Temporal trends in δ13C were measured, and revealed that interspecific variation was displayed throughout the year. This work documents interspecific variation in the nutrient dynamics of 3 common seagrasses in South Florida, indicating that interpretation of elemental and stable isotope values needs to be species specific

Mechanisms of Bicarbonate Use Influence the Photosynthetic Carbon Dioxide Sensitivity of Tropical Seagrasses

The photosynthetic bicarbonate () use properties of three widely distributed tropical seagrasses were compared using a series of laboratory experiments. Photosynthetic rates of Thalassia testudinum, Halodule wrightii, and Syringodium filiforme were monitored in an enclosed chamber while being subjected to shifts in pH and dissolved inorganic carbon. Specific mechanisms of seagrass use were compared by examining the photosynthetic effects of the carbonic anhydrase inhibitor acetazolamide (AZ). All seagrasses increased photosynthetic rates with reduced pH, suggesting a large effect of dissolved aqueous carbon dioxide (CO2(aq)). However, there was considerable interspecific variation in pH response. T. testudinum was highly sensitive, increasing photosynthetic rates by 100% as the pH was reduced from 8.2 to 7.4, whereas rates in H. wrightii and S. filiforme increased by only 20% over a similar range, and displayed prominent photosynthetic plateaus, indicating an increased capacity for use. Additional incubations that manipulated [] under constant [CO2(aq)] support these findings, as only H. wrightii and S. filiforme increased photosynthetic rates with increasing []. T. testudinum responded to AZ addition, indicating that carbonic anhydrase enzymes facilitate limited use. H. wrightii and S. filiforme showed no response to AZ, suggesting alternate, more efficient mechanisms of use. Estimated kinetic parameters, Ks(CO2) and Vmax, revealed interspecific variation and further support these conclusions. Variation in photosynthetic pH responses and AZ sensitivity indicate distinctions in the carbon use properties of seagrasses exposed to similar environmental conditions. These results suggest that not all seagrasses will similarly respond to future increases in CO2(aq) availability. Attention towards potential shifts in competitive interactions within multispecific seagrass beds is warranted

Demeanor, Race, and Police Perceptions of Procedural Justice: Evidence from Two Randomized Experiments

President Obama’s Task Force on 21st Century Policing recently endorsed procedural justice as a way to restore trust between police and communities. Yet police–citizen interactions vary immensely, and research has yet to give sufficient consideration to the factors that might affect the importance officers place on exercising procedural justice during interactions. Building on research examining “moral worthiness” judgments and racial stereotyping among police officers, we conducted two randomized experiments to test whether suspect race and demeanor affect officers’ perceptions of the threat of violence and importance of exercising procedural justice while interacting with suspicious persons. We find that suspect race fails to exert a statistically significant effect on either outcome. However, demeanor does—such that officers perceive a greater threat of violence and indicate it is less important to exercise procedural justice with disrespectful suspects. These findings have implications for procedural justice training, specifically, and police–community relations more broadly

Dynamic critical behaviour in Ising spin glasses

The critical dynamics of Ising spin glasses with Bimodal, Gaussian, and Laplacian interaction distributions are studied numerically in dimensions 3 and 4. The data demonstrate that in both dimensions the critical dynamic exponent $z_{\rm c}$, the non-equilibrium autocorrelation decay exponent $\lambda_c/z_{\rm c}$, and the critical fluctuation-dissipation ratio $X_{\infty}$ all vary strongly and systematically with the form of the interaction distribution.Comment: 8 pages, 4 figures, version to appear in Phys. Rev.

Command-level Police Officers’ Perceptions of the “War on Cops” and De-policing

Policing has been the subject of intense public scrutiny for the better part of two years after several high-profile police killings of unarmed African Americans across the United States. The scrutiny has been so extreme that some contend there is currently a “war on cops”—whereby citizens are emboldened by protests and negative media coverage of the police, and are lashing out by assaulting police officers more frequently. In response, it is argued that officers are de-policing (i.e. avoiding proactive stops). We surveyed command-level police officers from a southeastern state about their attitudes concerning the war on cops and de-policing. The majority of our sample believed there has been a war on cops over the last two years. Moreover, officers who felt strongly about the existence of a war on cops were more likely to believe that de-policing is common among officers in today’s world of law enforcement

Negative relationships between the nutrient and carbohydrate content of the seagrass Thalassia testudinum

This study documents relationships between plant nutrient content and rhizome carbohydrate content of a widely distributed seagrass species, Thalassia testudinum, in Florida. Five distinct seagrass beds were sampled for leaf nitrogen, leaf phosphorus, and rhizome carbohydrate content from 1997 to 1999. All variables displayed marked intra- and inter- regional variation. Elemental ratios (mean N:P ± S.E.) were lowest for Charlotte Harbor (9.9 ± 0.2) and highest for Florida Bay (53.5 ± 0.9), indicating regional shifts in the nutrient content of plant material. Rhizome carbohydrate content (mean ± S.E.) was lowest for Anclote Keys (21.8 ± 1.6 mg g−1 FM), and highest for Homosassa Bay (40.7 ± 1.7 mg g−1 FM). Within each region, significant negative correlations between plant nutrient and rhizome carbohydrate content were detected; thus, nutrient-replete plants displayed low carbohydrate content, while nutrient-deplete plants displayed high carbohydrate content. Spearman\u27s rank correlations between nutrient and carbohydrate content varied from a minimum in Tampa Bay (ρ = −0.2) to a maximum in Charlotte Harbor (ρ = −0.73). Linear regressions on log-transformed data revealed similar trends. This consistent trend across five distinct regions suggests that nutrient supply may play an important role in the regulation of carbon storage within seagrasses. Here we present a new hypothesis for studies which aim to explain the carbohydrate dynamics of benthic plants

Ocean Acidification Partially Mitigates the Negative Effects of Warming on the Recruitment of the Coral Orbicella faveolata

Ocean acidification and ocean warming constitute major threats to many calcifying reef organisms, including scleractinian corals. The combined effects of these two environmental stressors on the earliest life history stages of reef calcifiers remain poorly studied, particularly for Atlantic corals. Here, we investigate how acidification and warming influence the fertilization success, larval survivorship, and larval settlement of the threatened Atlantic coral, Orbicella faveolata. Gametes and larvae from O. faveolata were subjected to a factorial combination of warming (ambient versus + 1.5 °C) and acidification (ambient versus − 0.2 pH units) projected to occur by the year 2050. O. faveolata individuals were maintained in the same treatments throughout all early life history stages investigated. The fertilization success of O. faveolata was not affected by acidification, warming, or their combination. However, during larval development, warming caused complete mortality and prevented any subsequent settlement. Interestingly, these negative effects of warming were mitigated when combined with ocean acidification, such that both larval survivorship and settlement increased by 41% in the combined treatment relative to the isolated warming treatment. Our research suggests that temperature-induced increases in larval metabolism may be counterbalanced by acidification, which serves to reduce larval metabolism. Notwithstanding, larval survivorship and settlement were still reduced by 50% under combined acidification and warming relative to the ambient treatment, indicating that climate change will continue to serve as major stressor during the early life history stages of corals, jeopardizing the resilience of Caribbean reefs