Beneath the Gypsum Dunes: Cenozoic History of Wind and Water from a Core Drilled at White Sands, New Mexico

White Sands, New Mexico is the largest gypsum dune field on planet Earth, the result of reworking of gypsum deposits. The dunes have been well studied, but the Cenozoic history preceding the formation of the dune field has been poorly studied. A core drilled to a depth of 192 ft (58.5 m) beneath the modern dune field contains deposits from saline lakes, sandflats, perennial freshwater lakes, perennial brackish to saline lakes, and saline mudflats. The core is composed of bottom-growth bedded gypsum, gypsum sandstone and siltstone, mixed siliciclastic-gypsum sandstones and siltstones, laminated siliciclastic mudstones, gypsum mudstones, and carbonate mudstones. Bottom-growth bedded gypsum was precipitated from saline lakes. Gypsum sandstones and siltstones were deposited by eolian processes. Mixed siliciclastic-gypsum sandstones and siltstones were deposited during periods of increased surface water inputs. Laminated siliciclastic mudstones were deposited in perennial freshwater lakes. Calcite mudstone containing charophytes and ostracods were deposited in shallow, perennial brackish to saline lakes. Gypsum mudstones indicate either shallow saline lakes or saline mudflats. Wavy lamina, climbing ripple cross-bedding, and dewatering structures in gypsum mudstones are evidence for rapid deposition of sediment by shallow, decelerating surface waters such as sheetfloods. Mudcracks and eolian reworked gypsum grains are evidence for subaerial exposure. Black beds, possibly manganese oxides, were present at two depths in the core. Abundant displacive gypsum is interpreted as evidence for extensive saline groundwaters. Gypsum grain size and shape provide insight into production and subsequent transport of grains. Gypsum sandstones in the upper 80 ft (24.4 m) were commonly composed of very lightly reworked gypsum grains displacive in origin and are evidence for saline mudflats and subsequent subaerial exposure. The high porosity of these units indicates that a large quantity of fine-grained sediment was deflated. Seeds and other organic material were found throughout the core but were most abundant in the upper 80 ft (24.4 m) of core. A radiocarbon age date of 22 ka was determined from a seed at 35.4’ ft depth. Although the timespan of deposition of the core sediments is not known, it is estimated that the sediments at the base of the core may be as old as ~200 ka, due to the diverse assemblage of megafauna fossils found throughout White Sands and Bull Lake Glaciation. Sediment in the White Sands Core was deposited from perennial and ephemeral saline lakes, sandflats, perennial freshwater lakes, perennial brackish to saline lakes, and saline mudflats. There was abundant evidence for eolian processes. Two periods of perennial freshwater lake deposition and several saline lake deposits, as well as common eolian deposits strongly suggest fluctuations in climatic humidity and aridity during the Pleistocene

An array of fabry-perot optical-channels for biological fluids analysis

This paper describes a biosystem (biological system) used to measure the concentration of biochemical substances in urine, serum, plasma or cerebrospinal fluid. Rather than just one channel, it comprises 16 optical-channels that enable the measurement of the concentration of 16 different biochemical substances. An array of 16 optical filters based on Fabry-Perot thin-films optical resonators has been designed. Each optical-channel is sensitive in a single wavelength with a full-width-half-maximum (FWHM) of 7 nm. The filter fabrication requires only four masks, used with different etch time. A commercially available band-pass optical filter with a band-pass wavelength in 450–650 nm is used. The biosystem requires only a white light source for illumination due the use of selective optical filters.Fundação para a Ciência e a Tecnologia (FCT) - SFRH/BD/1281/2000, POCTI/33747/ESE/1999 – Fundo Europeu para o Desenvolvimento Regional

Biological microsystem for measuring uric acid in biological fluids

This paper describes a biological microsystem (bio-system) for measuring uric acid concentration in serum, plasma or urine. Its operation is based on optical absorption in a well-defined part of the visible spectrum. The bio-system is composed by two dies: one is fabricated in polystyrene and contains the microchannels and the other is fabricated in a CMOS standard process and contains the photodetector and readout electronics. The uric acid concentration is measured by using a mixture of 14µl of infinity™ uric acid reagent with 0.25µl of sample. The achieved sensitivity is 0.33 mg/dl (±0.6% of the value in urine of a healthy person), with a 1mm lightpath. Using an optical absorption method, a maximum peak at wavelength λ = 494 nm, is detected. This bio-system can be included in the group of low-cost disposable devices for biological fluids analysis.Fundação para a Ciência e a Tecnologia (FCT) - SFRH/BD/1281/2000, POCTI/33747/ESE/1999), FEDER

High fidelity, high yield production of microfluidic devices by hot embossing lithography : Rheology and stiction

We discuss thermoforming of thermoplastic polymers for the hot-embossing lithographic (HEL) fabrication of microfluidic chips near equilibrium conditions that minimize elastic recoil for optimal motif replication. While HEL is often simplistically described as the transfer of micro- and nano-motifs into heat-softened thermoplastic materials, we describe our rational approach to selecting appropriate processing parameters.Peer reviewed: YesNRC publication: Ye

Footprints preserve terminal Pleistocene hunt? Human-sloth interactions in North America

Predator-prey interactions revealed by vertebrate trace fossils are extremely rare. We present footprint evidence from White Sands National Monument in New Mexico for the association of sloth and human trackways. Geologically, the sloth and human trackways were made contemporaneously, and the sloth trackways show evidence of evasion and defensive behavior when associated with human tracks. Behavioral inferences from these trackways indicate prey selection and suggest that humans were harassing, stalking, and/or hunting the now-extinct giant ground sloth in the terminal Pleistocene

Recent Developments in Public Health Nursing in the Americas

This study presents an assessment of the participation and training of nurses in public health areas in the Americas. Information was gathered through a literature review and interviews with key informants from Mexico, Colombia, and Paraguay. Results demonstrate that there is significant variation in definitions of public health nursing across the region and current systematized data about the workforce profile of public health nursing personnel is not available for many countries in the Americas. There are significant regional differences in the levels and types of training of nurses working in public health areas and an increasing number of nurses are pursuing training in public health at the master’s and doctoral levels. Many nurses carry out some or all of the essential functions of public health, but are not considered to be public health nurses. Generally, auxiliary and technical nurses have a broader presence in public health areas than professional nurses. In the future, regional health systems reforms should support increased recruitment and training of public health nurses, as well as stronger roles in public health research and health care at the individual, community, and population levels