Oxygen minimum zone expansion in the eastern tropical North Pacific during deglaciation

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/95396/1/grl21420.pd

Efektifitas Strategi Republik Rakyat Tiongkok Dalam Menguasai Laut China Selatan Pasca Putusan Badan Arbitrase Internasional 2016

This research explains the Chinese strategy ineffectiveness to dominate the South China Sea post Permanent Court Arbitration in 2016. The Court declined the China\u27s nine dash line claim and decided to accept Philipine\u27s claim on the region dispute. This research also explores the Chinese strategy to dominate the South China Sea which militarily speaks louder regarding to its massive military power development and its huge number of economic power especially since 1990s.The research applies two approach which are balance of power and maritme security approach. The maritime security approach consists of two aspects: maritme security regime and maritime security community. The maritime security approach is used to explain the South China Sea regional secuity complexity. The strategy theory is used to explain China\u27s strategy to dominate the South China Sea. This research is developed by qualitative methods with library studies technique.The result of this research shows that South China Sea regional security problem complexity has caused China\u27s strategy became ineffective. These complexity consists of China\u27s aggresiveness in the region, the internal and external balance of power in the region, and security dilemma in the South China Sea. These complexity have made China\u27s strategy became ineffective

Iron limitation in the Western Interior Seaway during the Late Cretaceous OAE 3 and its role in phosphorus recycling and enhanced organic matter preservation

The sedimentary record of the Coniacian–Santonian Oceanic Anoxic Event 3 (OAE 3) in the North American Western Interior Seaway is characterized by a prolonged period of enhanced organic carbon (OC) burial. This study investigates the role of Fe in enhancing organic matter preservation and maintaining elevated primary productivity to sustain black shale deposition within the Coniacian–Santonian-aged Niobrara Formation in the USGS #1 Portland core. Iron speciation results indicate the development of a reactive Fe limitation coeval with reduced bioturbation and increased organic matter preservation, suggesting that decreased sulfide buffering by reactive Fe may have promoted enhanced organic matter preservation at the onset of OAE 3. An Fe limitation would also provide a feedback mechanism to sustain elevated primary productivity through enhanced phosphorus recycling. Additionally our results demonstrate inconsistencies between Fe-based and trace metal redox reconstructions. Iron indices from the Portland core indicate a single stepwise change, whereas the trace metal redox proxies indicate fluctuating redox conditions during and after OAE 3. Using Fe speciation to reconstruct past redox conditions may be complicated by a number of factors, including Fe sequestration in diagenetic carbonate phases and efficient sedimentary pyrite formation in a system with limited Fe supply and high levels of export production

Assessing oxygen depletion in the Northeastern Pacific Ocean during the last deglaciation using I/Ca ratios from multiple benthic foraminiferal species

Paleo‐redox proxies are crucial for reconstructing past bottom water oxygen concentration changes brought about by ocean circulation and marine productivity shifts in response to climate forcing. Carbonate I/Ca ratios of multiple benthic foraminifera species from Ocean Drilling Program Hole 1017E—a core drilled within the Californian oxygen minimum zone (OMZ), on the continental slope—are employed to reexamine the transition from the well‐oxygenated last glacial into poorly oxygenated modern conditions. The redox and export productivity history of this site is constrained by numerous proxies used to assess sensitivity of I/Ca ratios of benthic foraminifera to changes in bottom and pore water O2 concentrations. Reconstructed iodate (IO3−) availability is from the I/Ca ratio of epifaunal (Cibicidoides sp.), shallow infaunal (Uvigerina peregrina), and deep infaunal (Bolivina spissa) foraminifera. The reconstructed IO3− availability profile is used to determine the contribution of bottom water O2 relative to oxidant demand on pore water O2 concentrations. These results suggest that high export productivity on the California Margin drove low pore water O2 concentrations during the Bølling. In contrast, low bottom water O2 concentrations at 950 m water depth only contributed to reduced sediments during the Allerød. Increased contribution of modified North Pacific Intermediate Water to the California Current System ventilated the California OMZ during the late glacial and the Younger Dryas such that water overlying the site was oxygenated. These results highlight the promising potential of this new proxy for understanding the relative influence of bottom water O2 concentration and pore water oxidant demand on OMZs.Plain Language SummaryIodine is a highly redox‐sensitive element, is well mixed in the ocean, and is one of the first elements to respond to changes in ocean redox. In an oxic water column it is found as IO3−, and with decreasing dissolved O2 concentration it is reduced to I−. In foraminiferal calcite, iodate is thought to substitute for carbonate ions proportionate to the IO3− concentration of the water column, with the potential to be a quantitative proxy for detecting changes in oxygenation of bottom waters. However, core top studies indicate significant interspecies variability of I/Ca in response to O2. Here we measured the I/Ca ratios of multiple benthic foraminiferal species from Ocean Drilling Program‐1017E, a high‐resolution core on the California margin of the Northeast Pacific Ocean, to reconstruct bottom and pore water iodate availability to reexamine the oxygenation history of the California oxygen minimum zone to investigate the potential of this proxy for reconstructing the relative influence of bottom and pore water oxidant demand in response to millennial‐scale climate changes compared with previously published trace metal redox proxies.Key PointsThree benthic foraminifera species show expected I/Ca ratios in Northeast Pacific core record relative to their depth habitatForaminiferal I/Ca‐based O2 reconstructions are supported by multiple proxies in the same sediment samplesOxidant demand was greatest during the Bølling; pore and bottom waters were most oxygenated during the Younger Dryas and last glacialPeer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/138363/1/palo20430_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/138363/2/palo20430.pd

An Implementation of Error Minimization Data Transmission in OFDM using Modified Convolutional Code

This paper presents about error minimization in OFDM system. In conventional system, usually using channel coding such as BCH Code or Convolutional Code. But, performance BCH Code or Convolutional Code is not good in implementation of OFDM System. Error bits of OFDM system without channel coding is 5.77%. Then, we used convolutional code with code rate 1/2, it can reduce error bitsonly up to 3.85%. So, we proposed OFDM system with Modified Convolutional Code. In this implementation, we used Software Define Radio (SDR), namely Universal Software Radio Peripheral (USRP) NI 2920 as the transmitter and receiver. The result of OFDM system using Modified Convolutional Code with code rate is able recover all character received so can decrease until 0% error bit. Increasing performance of Modified Convolutional Code is about 1 dB in BER of 10-4 from BCH Code and Convolutional Code. So, performance of Modified Convolutional better than BCH Code or Convolutional Code.Keywords: OFDM, BCH Code, Convolutional Code, Modified Convolutional Code, SDR, USR

Diagenetic behavior of barite in a coastal upwelling setting

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/95374/1/palo1635.pd

Is pore water oxygen content decoupled from productivity on the California Margin? Trace element results from Ocean Drilling Program Hole 1017E, San Lucia slope, California

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/95250/1/palo1223.pd