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Mineralogy and Geochemistry of a Lithium and Boron Enriched Stratiform Ore Zone in the Cave Spring Formation, Rhyolite Ridge, NV, USA
No full textThe Rhyolite Ridge Project in the Silver Peak Range contains lithium and boron mineralization hosted by late Miocene-early Pliocene strata-bound sediments in an intermontane valley. ioneer USA Corporation is developing this project and is the industry-sponsor for this research along with the USGS and CREG. A lacustrine section, the Cave Spring Formation, measures up to 1,500 feet thick and hosts the sediments of interest. The unit with economic potential is the middle unit: a 60-foot interval called the Searlesite layer (B5). It is mineralized with both lithium clays and boron and is the targeted ore zone and the focus of this research. The younger, marl-rich member of this unit, the Li-Marl layer, shows no searlesite but has higher concentrations of lithium, which is hosted in smectite-rich interbeds.This research tests the hypothesis that precipitation of the Searlesite and Li-Marl layers of the Cave Spring Formation fits within the framework of the Closed Hydrologic System Diagenesis (CHSD) Model: these pelitic sediments required a saline alkaline lake with inputs of tuffaceous material to create the favorable chemistry for diagenesis of volcanic glass and subsequent precipitation of clays, zeolites, searlesite, and K-feldspar. This diagenetic alteration sequence shows a progression towards altered mineral assemblages observed in the Searlesite layer, where Li concentration in clay positively correlates with the degree of smectite-illite transformation and searlesite precipitation.Detailed mineralogical and geochemical analysis of 17 samples across the Li-Marl and Searlesite layers distinguishes the two layers and provides insight into the depositional environment of the ore zone and the evolution of the pore water during deposition of the younger material. The abrupt change in geochemistry between these layers is striking, and the genetic relationship between the mineralogy and the economic value of the sediments is directly related to the paleo lake conditions. The CHSD model states that rocks in deeper alkaline lakes with density-driven circulation will show more illitization of smectite and more authigenic K-feldspar than those in shallower waters or near basin margins; dense, diagenetic fluids will concentrate in basin-lows, driving precipitation these alteration products. Illite has been demonstrated to be more favorable in processing for lithium due to its lack of swelling characteristics while also being observed to concentrate lithium more effectively. The Searlesite layer exhibits characteristics of a deeper lake with a mineral assemblage reflecting the more highly progressed alteration sequence described in the CHSD model, including mixed-layer illite-smectite clays. The overlying Li-Marl layer is primarily characterized by a minimally altered mineral assemblage reflecting a shallower lake, including a dominant proportion of neoformed Mg-smectite clays.Seventeen samples from one core hole �" SBH-086 �" characterize the lacustrine sediments of the Li-Marl and Searlesite layers of the Cave Spring Formation. The minerals identified include carbonates such as calcite, dolomite and strontianite; searlesite; celadonite mica;zeolites such as analcime, heulandite and phillipsite; and Li-bearing clays that form as Mg-smectite or disordered I/S mixed-layer clays �" interpreted to be composed of Mg-smectite resembling hectorite and Al-illite. The highly mineralized Searlesite layer represents the most diagenetically altered material and the mineral suite in the Searlesite layer is the result of this diagenesis in the presence of boron. X-ray diffraction techniques are employed to interpret mineralogy in the fine-grained sediments, and geochemical analysis and modeling determined the clay structural formulas of the clays. These data enhance understanding of the Rhyolite Ridge deposit and the conceptual deposit model, which could prove useful for additional discovery of analogous deposits in other locations. Additionally, recovery and processing of the ore may be enhanced by quantifying variation in grade as a function of clay and borate mineralogy, as well as cation ratios of important elements
Geographic Origin and Life History Characteristics Predict the Responses of Plants to Reintroduction of a Native Herbivore
Get PDFIn response to the decline of large mammals in many parts of the world, a wealth of programs have been initiated over the past century to reintroduce extirpated taxa into parts of their historical range. Although these reintroductions have been a resounding success in many cases, and extensive research has been conducted to understand the dynamics of reintroduced populations, remarkably little attention has been focused on how the return of long-absent mammals �" especially herbivores �" has affected plant communities in recipient ecosystems. The response of plant communities to reintroduced herbivores will likely be complex, given that reintroduction sites have often been invaded by many non-native plant species and these taxa and their native counterparts vary greatly in life history characteristics and life forms. Here, we summarize results from a 25-year-old exclosure experiment stratified across three grassland types to examine the effects of reintroduced tule elk ( Cervus canadensis nannodes ) on a coastal plant community in northern California. Our results indicate that elk increased the dominance, species richness, and relative cover of exotic plant species, with the most abundant group in our system �" exotic annual graminoids �" increasing cover by 25%. We also found that elk had mixed effects on native species, with no effects on native graminoids and negative effects on native forbs and shrubs. The latter finding indicates that elk slowed the progression of woody encroachment in this system. Offering support for the biotic resistance hypothesis, we found that the prevalence of exotic species in our system decreased with increasing native richness, and elk dampened this relationship. Finally, we often found that the effects of elk on the plant community were context dependent, varying both spatially and temporally. In conclusion, our results highlight an important but sobering reality �" conservation efforts that reintroduce formerly extirpated mammals to parts of their former range will often have a complex array of desirable and undesirable effects on recipient plant communities
2024 Accelerated Implementation and Deployment of Pavement Technologies (AIDPT) Pooled Fund Peer Exchange on Balanced Mix Design (BMD): Outcomes Summary, FHWA-HIF-24-066 2024
No full text15 states across the United States (U.S.) gathered for a peer exchange and discussion on implementation activities to support Balanced Mix Design (BMD). The peer exchange was sponsored by the Federal Highway Administration (FHWA). The 15 States met to discuss state of knowledge, identify successes, current activities and research, and research and implementation gaps pertaining to challenges discussed during previously held regional peer exchanges. The peer exchange was held at National Center for Asphalt Technology (NCAT) in Auburn, Alabama. This summary report focuses on BMD state of knowledge, gaps, and challenges to implementation, performance testing protocols, management challenges, acceptance details, key takeaways, and emerging themes
Relationship Among Tongue Pressures in Healthy, English Monolingual Children Aged Four Years in the United States
Get PDFObjective: The purpose of this study was to establish male and female anterior and posterior normative maximum isometric tongue pressures and anterior and posterior tongue pressure ratios in four-year-olds. Tongue pressures were examined for sex differences. Methods: Researchers analyzed and compared anterior and posterior tongue pressures of 48 English monolingual, typically developing four-year-olds from preschools in Nevada and Washington State using the Iowa Oral Pressure Instrument. Results: Statistical analysis suggests an average anterior tongue pressure of 28.35kPa ( SD = 7.807) for females and 28.41kPa ( SD = 7.908) for males and an average posterior pressure of 26.65kPa ( SD = 8.23) for females and 27.75kPa ( SD = 6.988) for males. The calculated anterior-posterior pressure ratio was 1.02 for males and 1.06 for females. Conclusions: Results indicate that the pressure exerted by the tongue of a four-year-old is relatively the same from anterior to posterior, regardless of sex. Findings of anterior tongue pressure align with the limited existing data; however, posterior pressure in four-year-olds was not previously investigated. The ratios are the first established for anterior and posterior tongue pressure
Vision as a Function of the Gait Cycle
Get PDFThe human visual system plays a crucial role in guiding locomotion, enabling us to navigate the world and interact with our environment. As we navigate, we must stabilize the world on the eye. If we fail to stabilize the image on the eye, it will result in reduced visual acuity. There are physical and neural mechanisms that perform image stabilization within the brain. The brain may be able to leverage the periodicity of movement and neural activity during locomotion. This periodicity may allow the brain to predict the future movement of body movements, potentially negating excessive amounts of force on the body that would destabilize the image on the eye. However, these mechanisms underlying the coordination of vision and movement during walking are not yet fully understood. In this dissertation, I present work that evaluates the periodicity of vision during walking, both perceptually and with eye movement analyses. The act of walking does not seem to affect visual perception, namely contrast sensitivity and binocular rivalry. However, across the stride cycle we observed that periods of high transient force, such as when the heel hits the ground, cause increases in eye velocity and decreases in contrast sensitivity. In binocular rivalry, we observed that the dynamics were influenced by the heel strike and toe-off phases of the step cycle. Furthermore, walking speed may also play a role in affecting the dynamics of binocular rivalry. We then developed software for tracking head and eye movements in natural environments. We were able to bin the head and eye data as a function of the step cycle. In summary, we observed that the periodicity of locomotion affects eye and head movements, as well as visual perception. This dissertation provides valuable insights into sensory information integration during locomotion
Retrospective Cue Benefits in Visual Working Memory are Limited to a Single Item at a Time
Get PDFWorking memory (WM) performance can be improved by an informative cue presented during storage. This effect, termed a retrocue benefit, can be used to study limits on how human observers select and prioritize information stored in WM for behavioral output. There is disagreement about whether retrocue benefits extend to multiple WM items. One possibility is that relative to no- or neutral-cue trials multiple retrocues improve some aspects of memory performance (e.g., a reduction in random guessing) while worsening others (e.g., an increase in the probability of reporting a non-probed item). We tested this possibility in three experiments. Participants remembered arrays of four orientations or colors over a brief delay. One, two, or all four of these items were retrospectively cued, and at the end of the trial a single item was probed for recall. Participants’ recall errors were lower during cue-one relative to cue-two and cue-four trials, and this benefit was driven primarily by a reduction in random guessing during cue-one trials. Moreover, recall precision, swap errors (i.e., reporting a non-probed item), and guessing rates were statistically indistinguishable across cue-two and cue-four trials. Thus, multiple simultaneously presented retrospective cues led to no performance improvement relative to an uninformative cue, providing further evidence that retrocue benefits in WM performance are limited to a single item at a time
Investigating Herpesvirus Replication and Virus-Host Interactions During SARS-CoV-2 Co-Infections
No full textKaposi's sarcoma-associated herpesvirus (KSHV) is a gamma-herpesvirus in the Herpesviridae family. KSHV is an oncogenic virus and is the causative agent of Kaposi's sarcoma (KS), Multicentric Castleman's Disease (MCD), primary effusion lymphoma (PEL), and Kaposi Sarcoma Inflammatory Cytokine Syndrome (KICS). KSHV, like all herpesviruses, has a bi-phasic replication cycle consisting of a latent phase with periodic episodes of lytic reactivation. Within the replication complex, the DNA polymerase processivity factor plays a critical role in viral DNA synthesis through interactions with both viral and cellular components. Previous studies have described various functional domains of ORF59. However, the regions responsible for interactions with viral mRNA transport accumulation protein ORF57 and viral polyadenylated nuclear (PAN) RNA remained unexplored. Using ORF59 deletion mutants in KSHV BACmid, we identified multiple domains of ORF59 (amino acids 51-100, 251-300, and 351-396) that interact with PAN RNA. Notably, the absence of association with ORF59 led to an aberrant localization pattern of PAN RNA, forming aggregates concentrated into foci. Interestingly, amino acids 51-100 were found to be essential for interaction with ORF57, indicating a shared interaction domain for PAN RNA and ORF57. To further elucidate the role of ORF59 in viral replication, a small DsRed-tagged polypeptide spanning amino acids 30-100 of ORF59 was created. Transfection of this polypeptide into iSLK-WT cells resulted in a dominant-negative inhibition of virus replication, leading to decreased infectious virion production. To understand why nuclear punctate formed within specific ORF59 deletion domains, we investigated the role of paraspeckle nuclear bodies, comprising core ribonucleoproteins SFPQ and NONO during lytic KSHV replication. Using SFPQ immunoprecipitation followed by mass spectrometry, we found interactions between SFPQ and KSHV viral proteins, ORF10, ORF59, ORF61, ORF67, ORF11, ORF21, ORF50, ORF52, ORF57, ORF6, ORF25, and ORF69. Further analysis identified the region spanning amino acids 101-150 of ORF59 as the interaction domain with SFPQ. By generating a dominant-negative polypeptide of ORF59 amino acids 101-150, we disrupted the interaction between SFPQ and full-length ORF59, resulting in decreased virus production. Interestingly, co-immunoprecipitation experiments with other human herpesvirus processivity factors revealed similar interaction with SFPQ, suggesting a potentially conserved requirement for SFPQ across multiple herpesviruses. Lastly, with the emergence of SARS-CoV-2 and the ongoing COVID-19 pandemic, the association between human cytomegalovirus (HCMV) seropositivity and increased COVID-19 severity has gained attention. HCMV is a ubiquitous beta-herpesvirus with a high seroprevalence worldwide and is a leading cause of congenital abnormalities and mortality in immunocompromised individuals. Our studies found CD14 + monocytes, one of the primary reservoirs of latency for HCMV, to be susceptible and permissive to SARS-CoV-2 infection. RNA-sequencing analysis revealed significant differences in cytokine-cytokine receptor interactions and inflammatory pathways in HCMV-latent CD14 + monocytes superinfected with replication-competent SARS-CoV-2. These findings provide insights into the heightened inflammatory response associated with co-infection, suggesting potential therapeutic interventions for severe cases of COVID-19 among HCMV-infected individuals. Overall, these studies contribute to our understanding of viral interactions and their implications for disease pathogenesis, highlighting potential therapeutic targets to mitigate the severity of viral infections, particularly in cases of co-infection
Janet Yellen's Role in US-China Economic Relations
No full textJanet Yellen, a distinguished American economist and policymaker, offers unique insights into China. She prioritized safeguarding American interests by advocating a "friend-shoring" strategy, diverging from Trump's isolationism. Yellen's commitment to boosting US investment and manufacturing was central to Bidenomics. Her tenure saw notable advancements, including the chip war. Dispelling the China currency manipulation myth, she refocused on domestic concerns like inflation and cautioned against complete China decoupling. Yellen promoted cooperation with China in various areas, from fentanyl control to climate change. Despite right-wing perceptions, she effectively protected US economic interests and improved US-China relations
Nevada State Climate Office Quarterly Report July-September 2024
No full textQuarterly Report and Outlook for notable weather and climate in Nevada through July-September 2024. English Version