753 research outputs found
William (Bill) Peterson's contributions to ocean science, management, and policy
© The Author(s), 2020. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Schwing, F. B., Sissenwine, M. J., Batchelder, H., Dam, H. G., Gomez-Gutierrez, J., Keister, J. E., Liu, H., & Peterson, J. O. William (Bill) Peterson's contributions to ocean science, management, and policy. Progress in Oceanography, 182, (2020): 102241, doi:10.1016/j.pocean.2019.102241.In addition to being an esteemed marine ecologist and oceanographer, William T. (Bill) Peterson was a dedicated public servant, a leader in the ocean science community, and a mentor to a generation of scientists. Bill recognized the importance of applied science and the need for integrated “big science” programs to advance our understanding of ecosystems and to guide their management. As the first US GLOBEC program manager, he was pivotal in transitioning the concept of understanding how climate change impacts marine ecosystems to an operational national research program. The scientific insight and knowledge generated by US GLOBEC informed and advanced the ecosystem-based management approaches now being implemented for fishery management in the US. Bill held significant leadership roles in numerous international efforts to understand global and regional ecological processes, and organized and chaired a number of influential scientific conferences and their proceedings. He was passionate about working with and training young researchers. Bill’s academic affiliations, notably at Stony Brook and Oregon State Universities, enabled him to advise, train, and mentor a host of students, post-doctoral researchers, and laboratory technicians. Under his collegial guidance they became critical independent thinkers and diligent investigators. His former students and colleagues carry on Bill Peterson’s legacy of research that helps us understand marine ecosystems and informs more effective resource stewardship and conservation
Estimating the Spatial Extent of Bottom-Water Hypoxia and Habitat Degradation in a Shallow Estuary
Bottom-water hypoxia (≤ 2 mg 1-1 dissolved oxygen [DO]) greatly modifies the benthic habitat of estuaries, depending upon spatial extent, duration, and frequency. Bottom-water hypoxia often develops under conditions of density stratification, which inhibits vertical mixing, and warm temperatures, which enhance biological oxygen demand. Long-term, mid-channel data from the Neuse River Estuary in North Carolina permitted evaluation of how stratification and temperature combined to affect DO concentrations at the bottom. Salinity stratification (DS) and water temperature (T) explained respectively 30 and 23% of the variance in bottom-water DO concentrations. The amount of salinity stratification required to induce bottom-water hypoxia declined with increasing water temperature. About 80% of observed hydrographic profiles exhibited bottom hypoxia when DS exceeded 5 psu and T exceeded 20°C. Using cross-channel hydrographic surveys as verification, we derived a general set of methods to estimate the lateral extent of low-DO bottom water from midchannel hydrographic profiles. The method involves cross-estuary and along-estuary extrapolation based on assumption of a flat oxycline. Occasional violation of this assumption resulted in modest overestimation in cross-channel extent of low DO. Application of this method produced estimates ranging from 0 to 116 km2 of bottom area (0 to 42% of the estuarine study area) exposed to hypoxia over all sample dates in summer 1997. The maximal bottom area exposed to hypoxia corresponded closely with an independent estimate of the area (100 km2) that experienced almost complete mortality of Macoma spp. clams, the key benthic resource for demersal fishes and crabs. Consequently, mid-channel hydrographic profiles taken along the mid-channel of the estuary can be employed to assess the spatial scale of bottom habitat degradation due to hypoxia
Rapidly expanding nuclear arsenals in Pakistan and India portend regional and global catastrophe
Pakistan and India may have 400 to 500 nuclear weapons by 2025 with yields from tested 12- to 45-kt values to a few hundred kilotons. If India uses 100 strategic weapons to attack urban centers and Pakistan uses 150, fatalities could reach 50 to 125 million people, and nuclear-ignited fires could release 16 to 36 Tg of black carbon in smoke, depending on yield. The smoke will rise into the upper troposphere, be self-lofted into the stratosphere, and spread globally within weeks. Surface sunlight will decline by 20 to 35%, cooling the global surface by 2° to 5°C and reducing precipitation by 15 to 30%, with larger regional impacts. Recovery takes more than 10 years. Net primary productivity declines 15 to 30% on land and 5 to 15% in oceans threatening mass starvation and additional worldwide collateral fatalities
A variational method based on weighted graph states
In a recent article [Phys. Rev. Lett. 97 (2006), 107206], we have presented a
class of states which is suitable as a variational set to find ground states in
spin systems of arbitrary spatial dimension and with long-range entanglement.
Here, we continue the exposition of our technique, extend from spin 1/2 to
higher spins and use the boson Hubbard model as a non-trivial example to
demonstrate our scheme.Comment: 36 pages, 13 figure
A Measurement of the Decay Asymmetry Parameters in \Xi_{c}^{0}\to \X^{-}\pi^{+}
Using the CLEO II detector at the Cornell Electron Storage Ring we have
measured the decay asymmetry parameter in the decay . We find , using the world average value of
we obtain . The physically allowed range of a decay
asymmetry parameter is . Our result prefers a negative value:
is at the 90% CL. The central value occupies the
middle of the theoretically expected range but is not yet precise enough to
choose between models.Comment: 10 pages postscript, also available through
http://w4.lns.cornell.edu/public/CLN
Observation of Two Narrow States Decaying into and
We report the first observation of two narrow charmed strange baryons
decaying to and , respectively, using data from
the CLEO II detector at CESR. We interpret the observed signals as the
and , the symmetric partners
of the well-established antisymmetric and .
The mass differences and
are measured to be and
, respectively.Comment: 11 pages, postscript file also available through
http://w4.lns.cornell.edu/public/CLN
Observation of New States Decaying into
Using 13.7 fb^{-1} of data recorded by the CLEO detector at CESR, we
investigate the spectrum of charmed baryons which decay into Lambda_c^+ pi^-
pi^+ and are more massive than the Lambda_{c1} baryons. We find evidence for
two new states: one is broad and has an invariant mass roughly 480 MeV above
that of the Lambda_c^+; the other is narrow with an invariant mass of 596 +- 1
+- 2 MeV above the Lambda_c^+ mass. These results are preliminary.Comment: 11 pages postscript, also available through
http://w4.lns.cornell.edu/public/CLN
Lifetime Differences, direct CP Violation and Partial Widths in D0 Meson Decays to K+K- and pi+pi-
We describe several measurements using the decays D0->K+K- and pi+pi-. We
find the ratio of partial widths, Gamma(D0->K+K-)/Gamma(D0->pi+pi-), to be
2.96+/-0.16+/-0.15, where the first error is statistical and the second is
systematic. We observe no evidence for direct CP violation, obtaining A_CP(KK)
= (0.0+/-2.2+/-0.8)% and A_CP(pipi = (1.9+/-3.2+/-0.8)%. In the limit of no CP
violation we measure the mixing parameter y_CP = -0.012+/-0.025+/-0.014 by
measuring the lifetime difference between D0->K+ K- or pi+pi- and the CP
neutral state, D0->K-pi+. We see no evidence for mixing.Comment: 14 pages postscript, also available through
http://w4.lns.cornell.edu/public/CLNS, submitted to PRD, Rapid Communicatio
First Observation of the Baryon and a New Measurement of the Mass
Using data recorded with the CLEO II and CLEO II.V detector configurations at
the Cornell Electron Storage Rings, we report the first observation and mass
measurement of the charmed baryon, and an updated measurement
of the mass of the baryon. We find
= 231.0 +- 1.1 +- 2.0 MeV, and
= 166.4 +- 0.2 +- 0.3 MeV, where the errors are
statistical and systematic respectively.Comment: 8 pages postscript, also available through
http://w4.lns.cornell.edu/public/CLN
Instances and connectors : issues for a second generation process language
This work is supported by UK EPSRC grants GR/L34433 and GR/L32699Over the past decade a variety of process languages have been defined, used and evaluated. It is now possible to consider second generation languages based on this experience. Rather than develop a second generation wish list this position paper explores two issues: instances and connectors. Instances relate to the relationship between a process model as a description and the, possibly multiple, enacting instances which are created from it. Connectors refers to the issue of concurrency control and achieving a higher level of abstraction in how parts of a model interact. We believe that these issues are key to developing systems which can effectively support business processes, and that they have not received sufficient attention within the process modelling community. Through exploring these issues we also illustrate our approach to designing a second generation process language.Postprin
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