Silicon isotopes in Arctic and sub-Arctic glacial meltwaters:The role of subglacial weathering in the silicon cycle

Glacial environments play an important role in high-latitude marine nutrient cycling, potentially contributing significant fluxes of silicon (Si) to the polar oceans, either as dissolved silicon (DSi) or as dissolvable amorphous silica (ASi). Silicon is a key nutrient in promoting marine primary productivity, contributingto atmosphericCO2 removal.We present the current understanding of Si cycling in glacial systems,focusingontheSiisotope(δ30Si)composition of glacial meltwaters. We combine existing glacial δ30Si data with new measurements from 20 subArctic glaciers, showing that glacial meltwaters consistently export isotopically light DSi compared with non-glacial rivers (+0.16‰ versus +1.38‰). Glacial δ30SiASi composition ranges from −0.05‰ to −0.86‰ but exhibits low seasonal variability. Silicon fluxes and δ30Si composition from glacial systems are not commonly included in global Si budgets and isotopic mass balance calculations at present. We discuss outstanding questions, including the formation mechanism of ASi and the export of glacial nutrients from fjords. Finally, we provide a contextual framework for the recent advances in our understanding of subglacial Si cycling and highlight critical research avenues for assessing potential future changes in these environments

A Plan for a Long-Term, Automated, Broadband Seismic Monitoring Network on the Global Seafloor

Establishing an extensive and highly durable, long‐term, seafloor network of autonomous broadband seismic stations to complement the land‐based Global Seismographic Network has been a goal of seismologists for decades. Seismic signals, chiefly the vibrations from earthquakes but also signals generated by storms and other environmental processes, have been processed from land‐based seismic stations to build intriguing but incomplete images of the Earth’s interior. Seismologists have mapped structures such as tectonic plates and other crustal remnants sinking deep into the mantle to obtain information on their chemical composition and physical state; but resolution of these structures from land stations is not globally uniform. Because the global surface is two‐thirds ocean, increasing the number of seismic stations located in the oceans is critical for better resolution of the Earth’s interior and tectonic structures. A recommendation for a long‐term seafloor seismic station pilot experiment is presented here. The overarching instrumentation goal of a pilot experiment is performance that will lead to the installation of a large number of long‐term autonomous ocean‐bottom seismic stations. The payoff of a network of stations separated from one another by a few hundred kilometers under the global oceans would be greatly refined resolution of the Earth’s interior at all depths. A second prime result would be enriched understanding of large‐earthquake rupture processes in both oceanic and continental plates. The experiment would take advantage of newly available technologies such as robotic wave gliders that put an affordable autonomous prototype within reach. These technologies would allow data to be relayed to satellites from seismometers that are deployed on the seafloor with long‐lasting, rechargeable batteries. Two regions are presented as promising arenas for such a prototype seafloor seismic station. One site is the central North Atlantic Ocean, and the other high‐interest locale is the central South Pacific Ocean

A Case Study of Low-Mass Star Formation

This article synthesizes observational data from an extensive program aimed toward a comprehensive understanding of star formation in a low-mass star-forming molecular cloud. New observations and published data spanning from the centimeter wave band to the near infrared reveal the high and low density molecular gas, dust, and pre-main sequence stars in L1551.Comment: 24 pages, 21 figures, ApJS accepte

Delayed presentation of an isolated gallbladder rupture following blunt abdominal trauma: a case report

This is an Open Access article distributed under the terms of the Creative Commons Attribution Licens

The Lantern Vol. 49, No. 2, Spring 1983

• Time • The Lantern, 1933-1983 • The Battle • Lady Number 9 • That First Night • Wavering • If I Dared • The Hack • The Beauty of a Rose • H2O • The Island • Library • Unicorns • Prisoner of Myrin • How The Universe Was Won • On Success • I, The Poethttps://digitalcommons.ursinus.edu/lantern/1122/thumbnail.jp

Identification of rare-disease genes using blood transcriptome sequencing and large control cohorts.

It is estimated that 350 million individuals worldwide suffer from rare diseases, which are predominantly caused by mutation in a single gene1. The current molecular diagnostic rate is estimated at 50%, with whole-exome sequencing (WES) among the most successful approaches2-5. For patients in whom WES is uninformative, RNA sequencing (RNA-seq) has shown diagnostic utility in specific tissues and diseases6-8. This includes muscle biopsies from patients with undiagnosed rare muscle disorders6,9, and cultured fibroblasts from patients with mitochondrial disorders7. However, for many individuals, biopsies are not performed for clinical care, and tissues are difficult to access. We sought to assess the utility of RNA-seq from blood as a diagnostic tool for rare diseases of different pathophysiologies. We generated whole-blood RNA-seq from 94 individuals with undiagnosed rare diseases spanning 16 diverse disease categories. We developed a robust approach to compare data from these individuals with large sets of RNA-seq data for controls (n = 1,594 unrelated controls and n = 49 family members) and demonstrated the impacts of expression, splicing, gene and variant filtering strategies on disease gene identification. Across our cohort, we observed that RNA-seq yields a 7.5% diagnostic rate, and an additional 16.7% with improved candidate gene resolution

The Lantern Vol. 50, No. 1, Fall 1983

• Reaching for My Dream • All Hail • Appreciation • Egotism • Me (Dedicated to...) • Butterfly • Balloon and Bird • Never Again • Mother • The Deaf Ears • Healing • Distress • Silent Death • Whose Reality Is It Anyway? • To Helen • Luna Llena y Soledad • Saved • Jenny • Slope • A Poem in C Minor • A Birth of Proficiency • The Traveling Man • Competing With the Sea • To R. • The Child • And Besides • An Actress\u27 Demise • A Loving Tribute to Francis • Rapunzel • Memorieshttps://digitalcommons.ursinus.edu/lantern/1123/thumbnail.jp

Exoplanet Diversity in the Era of Space-based Direct Imaging Missions

This whitepaper discusses the diversity of exoplanets that could be detected by future observations, so that comparative exoplanetology can be performed in the upcoming era of large space-based flagship missions. The primary focus will be on characterizing Earth-like worlds around Sun-like stars. However, we will also be able to characterize companion planets in the system simultaneously. This will not only provide a contextual picture with regards to our Solar system, but also presents a unique opportunity to observe size dependent planetary atmospheres at different orbital distances. We propose a preliminary scheme based on chemical behavior of gases and condensates in a planet's atmosphere that classifies them with respect to planetary radius and incident stellar flux.Comment: A white paper submitted to the National Academy of Sciences Exoplanet Science Strateg