An upper bound for the genus of a curve without points of small degree

In this paper I prove that for any prime $p$ there is a constant $C_p>0$ such that for any $n>0$ and for any $p$-power $q$ there is a smooth, projective, absolutely irreducible curve over $\mathbb{F}_q$ of genus $g\leq C_p q^n$ without points of degree smaller than $n$.Comment: This is part of a Phd thesis at Universit\`a 'Sapienza' of Rom

A counterexample to 'Algebraic function fields with small class number'

I give a counter example of function field over GF(2) of genus 4 with class number one. This result contradicts a previous result in [2], Section 2 so that proof is wrong

Modular Curves with many Points over Finite Fields

We compute the number of points over finite fields of some classes of modular curves, namely $X_0(N)$, $X_0^+(N)$, without using explicit equations. In this way we could improve many lower bounds for the maximum number of points of a curve over finite fields

Geographic Correlation of Mental Health Google Search Terms and COVID-19 Fatality Rates

Not only have COVID-19 social distancing and quarantining measures transformed today’s society, but they have also exacerbated the mental health crisis in the United States. Understanding fear-induced responses and coping mechanisms due to unprecedented global events, such as the COVID-19 Pandemic, can enable health care providers to address their psychological impact and prepare appropriate treatment regimes. Despite numerous epidemic data platforms tracking COVID-19 fatalities, there is a limited understanding of Americans’ mental health during the COVID-19 Pandemic. This study investigates and quantifies the correlation between U.S. COVID-19 fatality rates over time and fear-related Google search terms by utilizing Google Trends and the Centers for Disease Control and Prevention (CDC) COVID-19 Tracker. Furthermore, in order to determine context-specific relationships between Google search terms and U.S. COVID-19 fatalities, a graphical analysis will be conducted to assess the data visually. Ultimately, this experiment provides insight on the psychological impact of highly stressful events, especially future global health events similar to the COVID-19 Pandemichttps://orb.binghamton.edu/research_days_posters_2022/1135/thumbnail.jp

Pleistocene foraminifera assemblages as a proxy for temperature in the Weddell Sea, ODP Site 693A

Climate conditions in the Weddell Sea during the Pleistocene can be inferred by examining the abundance of foraminifer species and mineral fragments in ocean sediment cores. In particular, Neogloboquadrina incompta is a useful temperature proxy, and the abundance of terrigenous sediments is an indication of ice rafting. Using percent abundances enables correlation with other climate studies and with a global δ18O isotope stack. The proxies examined indicate at least four oscillations between cold and warm conditions related to global glacial and interglacial stages between 950 and 450 kya, with associated shifts in sea ice extent and deep-water formation

The Upper Ocean at the End of an Ice Age: Using Proxies in Benthic Foraminifera to Investigate Intermediate Water Changes During the Last Glacial Termination

The ocean is an important component of the global climate system and plays a key role as a storage reservoir for heat and carbon. Under glacial conditions, the ocean sequestered carbon from the atmosphere, contributing to a cooler global climate. During the last glacial termination, that carbon was released back into the atmosphere, but the exact timing and mechanisms of this transfer are still not fully understood. This study examines waters from the intermediate depths of the Southern Ocean to gain insight into deglacial processes. Intermediate waters are capable of reacting to climate change on decadal timescales, making them a good candidate for catching the early part of deglacial changes. Geochemical proxies in benthic foraminifera provide information on the physical and chemical conditions of these water masses. Prior to applying the Mg/Ca–temperature proxy downcore, we performed a coretop calibration using the species Uvigerina peregrina for our southwest Pacific site. Thorough examination of coretop conditions and foraminifer chemistry yieled a globally-applicable Mg/Ca–temperature calibration, and a series of recommendations for utilizing U. peregrina in paleotemperature reconstructions. Using the resulting calibration as well as a calibration for a second species, Hoeglundina elegans, we reconstructed a paleotemperature record for site 79JPC (1163 m water depth), located in New Zealand’s Bay of Plenty. Temperatures of Antarctic Intermediate Water (AAIW) at this site support the hypothesis of a rapid global warming early during the last glacial termination, and provide further evidence for deglacial changes occurring on timescales much more rapid than those of the continental ice sheets. For a second perspective on deglacial changes in AAIW, we applied a similar approach to site 50GGC, located in the Indian Sector of the Southern Ocean. Using Cibicidoides wuellerstorfi and Cibicidoides kullenbergi, we reconstructed paleotemperature as well as carbonate ion concentrations. Unlike AAIW records from the Pacific and Atlantic basins, those at 50GGC show greater stability and a lower magnitude of change. The uniqueness of the records from 50GGC highlights the need for further study in this basin, and the need to separate concepts of “Indo-Pacific” deglacial change into “Indian sector” and “Pacific sector” components

Assessing the Reliability of the Benthic Mg/Ca–Temperature Proxy: a Uvigerina Core-top Study from New Zealand

Sediment cores from New Zealand’s Bay of Plenty and the Chatham Rise in the Southwest Pacific were sampled to establish a regional Mg/Ca–temperature calibration for the benthic foraminifer Uvigerina peregrina. Comparison of foraminiferal Mg/Ca from core-top sediments to local bottom water temperatures reveals a Mg/Ca–temperature relationship broadly consistent with previously published calibrations. In addition to bottom water temperatures, other environmental parameters are examined for possible influence on the Mg/Ca of foraminiferal calcite. Elderfield et al. (2006) proposed that such parameters may exert an influence at colder temperatures, particularly below temperatures of ~3oC (e.g. Lear et al., 2002; Elderfield et al., 2006; Bryan and Marchitto, 2008). Multiple cores, from water depths between 2400 and 3300 meters, yielded unexpectedly high Mg/Ca ratios (~1.35 mmol/mol) given the ambient bottom water temperatures of ~2oC. Several non-temperature influences were ruled out as the possible cause of the high Mg/Ca measurements. These include morphotype variations, dissolution, down-slope transport, inorganic calcite overgrowths, and carbonate ion saturation. Further analyses, including SEM/EDS analysis of the interior of test chambers, revealed the presence of aluminosilicate crystals growing within chambers of U. peregrina. It is hypothesized that authigenic aluminosilicate growths may present difficulties in measuring and interpreting Mg/Ca in infaunal foraminifera by contributing additional cations during analysis. This affects sediments from New Zealand, and may also occur in other locations. The chemical conditions required for such aluminosilicate precipitation are expected to include high detrital sediment inputs (i.e. fluvial or volcanic), intense surface ocean productivity (i.e. high biogenic silica flux), and high dissolved inorganic carbon concentrations in the water mass overlying the seafloor. Due to the widespread use of the benthic Mg/Ca paleotemperature proxy, it is important to identify any factors that could potentially complicate its use or interpretation. The observed aluminosilicate grains emphasize the need to look beyond the carbonate system when considering diagenetic influences on foraminiferal calcite. Factors such as pore water chemistry and sediment type could exert a significant influence on Mg/Ca measurements, potentially overwriting the Mg/Ca–temperature signal of foraminiferal calcite. Identifying the presence of silicate contaminants and the conditions that cause them to precipitate could enable a better understanding of the factors leading to Mg/Ca measurements that reflect factors other than primary temperature control. Our results suggest that SEM imaging of foraminifer chamber interiors, particularly in areas susceptible to aluminosilicate precipitation, should be done as part of the sample selection process, both in core-top sediments and in paleo records, to ensure production of quality Mg/Ca datasets without diagenetic overprinting