HEP Experiments. Learn more. Georges Aad Freiburg U. Published in: Eur. C 71 DOI: Citations per year 0 5 10 15 Abstract: arXiv. Note: 20 pages plus author list 37 pages total11 figures, 1 tables, submitted to Journal EPJ C updated author list. References Figures Field Florida U. Acta Phys. B 36 Acosta Florida U. D 70 Aaltonen Helsinki Inst. D 82 Vardan Khachatryan Yerevan Phys.
C 70 A Experimental work with sand and mud habitats highlights the importance of biodiversity from the bottom up. Sediments have a reputation for being flat and brown, and are certainly less glamourous than the colourful rocky pinnacles, seamounts and coral reefs that get media attention. However, soft sediments host a diverse array of organisms and play a pivotal role in marine ecosystem functioning. A coastal soft-sediment habitat at 6 m depth.
Sponges, tunicates, bivalves, crustaceans, worms, and burrowing urchins contribute to the great biodiversity and biocomplexity of soft-bottom seafloors. Photo: S. Conceptual depiction of complex interactions in coastal seafloor sediments. Click for detailed description. Sediments create a three-dimensional living environment for bottom-dwelling creatures, and animals can burrow deep within the sediment column up to 2 m below the sediment surface in the case of some crabs and shrimps. This contrasts with rocky systems, where plants and animals are generally confined to hard, impermeable surfaces.
Because sediment is an accumulation of particles that have settled to the seabed, it is generally rich in organic matter, with fresh new detritus continually falling to the seabed from above.
Animals inhabiting the sediment use this organic detritus as a source of food, but may also graze on microscopic algae that grow on the sediment surface. The sediment—seawater interface is permeable, so water fills the small gaps between particles.
This sedimentary pore water differs from the overlying seawater in many ways. The concentration of oxygen in pore water decreases rapidly with depth in the sediment, so animals living beneath the sediment surface must maintain access to an oxygen-rich supply. Also, concentrations of nutrients released by the breakdown of organic matter by bacteria are generally much greater in pore water than they are in overlying seawater.
The nutrients in pore water act as a fertiliser for algal growth, and the algae can only flourish with a combination of both sunlight and essential nutrients. Thus enhanced rates of oxygen and nutrients flowing into and out of the sediment are likely to affect benthic animals and plants. These flows, called fluxes, are measurements of the quantity moved per area per time for example, grams of nitrogen per m2 per day.
We can learn a lot about how the soft-sediment seafloor functions by understanding the fluxes of oxygen and nutrients. Although the sophistication of techniques used to measure fluxes has increased dramatically in recent years, the interpretation of flux data is still quite complicated, for many reasons. Soft sediments are inherently complex: bacteria, microalgae, and benthic invertebrates all influence oxygen and nutrient concentrations simultaneously, via direct and indirect pathways see diagram, right.
Fluxes are net results of all such interactions, some of which reinforce each other to increase or decrease flux, and some of which oppose each other. It takes a collaborative, interdisciplinary approach to understand the physical, geochemical, and ecological factors affecting flux rates: a lone scientist in any single discipline will likely overlook key elements in the system, and risk misinterpretation of results.
Biocomplexity is a new buzz word in the natural sciences which acknowledges the interactive and interdisciplinary feedback effects that are sometimes difficult to identify and quantify. Proponents of the biocomplexity concept cite the need to study whole systems, as they may exhibit special properties that are not predictable based on the sum of their component parts. Science that reduces complexity and confounding factors in carefully controlled field and laboratory experiments assumes, sometimes without basis, that results can be easily extrapolated to the real world.
Marine soft sediments: more diversity than meets the eye
NIWA scientists in Hamilton have begun studying biocomplexity in soft sediments. The studies involve measurements of water chemistry over time, the raw data from which fluxes are calculated. However, experiments have also included manipulations of important physical and biological drivers sunlight intensity, sediment mixing by large invertebrates so we can separate out the effects of different interacting components in the system.
Most importantly, we work with intact soft-sediment communities in order to capture the behaviour of the system as a whole. This requires scuba divers setting up equipment on the seafloor to capture the interactions within natural assemblages of bacteria, algae, and invertebrates. With three experiments run so far and others planned for next year, we are building our base of knowledge and learning how soft sediments perform in different seasons and with differing numbers of invertebrate individuals and species.
We know that disturbance to the seabed can remove key species and reduce biodiversity and that reductions in biological diversity may decrease ecosystem performance. By identifying good measures of ecosystem performance, NIWA scientists are now better positioned to make these linkages and inform coastal managers about the functional importance of marine soft sediments, the most widespread seafloor ecosystem on Earth.In hadronic collisions, interference between different production channels affects momentum distributions of multi-particle final states.
We further find that the non-abelian features of QCD interference can give rise to odd harmonic anisotropies. These findings indicate that the no-interaction baseline including QCD interference effects can make a sizeable if not dominant contribution to the measured v n coefficients in pp collisions. Prospects for analyzing QCD interference contributions further and their possible relevance for proton-nucleus and nucleus-nucleus collisions are discussed shortly. Download to read the full article text.
Gieseke, M. Seymour and A. Siodmok, A model of non-perturbative gluon emission in an initial state parton showerJHEP 06 [ arXiv Gieseke, P. B [ arXiv Kurkela, Initial state of heavy-ion collisions: isotropization and thermalizationNucl.
A [ arXiv Heinz and R.Garlic Butter Shrimp
Snellings, Collective flow and viscosity in relativistic heavy-ion collisionsAnn. C 77 [ arXiv Fischer and T. C 85 [ arXiv Bzdak, B.
Schenke, P. Tribedy and R. Venugopalan, Initial state geometry and the role of hydrodynamics in proton-proton, proton-nucleus and deuteron-nucleus collisionsPhys.
C 87 [ arXiv He, T. Edmonds, Z. Lin, F. Liu, D. Molnar and F. Wang, Anisotropic parton escape is the dominant source of azimuthal anisotropy in transport modelsPhys. B 68 [ arXiv C 76 [ arXiv Borghini, P. Dinh and J. Ollitrault, A new method for measuring azimuthal distributions in nucleus-nucleus collisionsPhys.Sherpas are recognized as the most capable mountaineers on the planet.
While it may be a bit overly dramatic to equate learning to cook fish with summiting Mount Everest, many people view the two obstacles as being equally insurmountable. The broad category of seafood contains the most diverse and abundant proteins available. There are only a couple dozen mammals and birds consumed regularly in the United States, while there are literally hundreds of fish and shellfish to choose from.
Americans fall into three camps with seafood:. I hope to help broaden the horizons of the home cook from the first group. I hope to help the second group become confident with a broad range of seafood cooking techniques. I hope to encourage the last group to sample a few of the many wonderful food items that come from our oceans.
I believe that seafood offers something for everyone if they can just cast off their preconceived notions that fish are all the same. My name is John Peery and I was once in the third group. I found my way to a love of seafood that I strive to share with everyone around me and so can you. Allow me to guide you and develop your knowledge of fish cookery with easy tutorials covering basic techniques along with simple guides to help you choose a seafood that is as adventurous as you want to be.
It is a super popular dish that is pretty easy to make and everyone loves shrimp. This recipe is not that special, except that it is.
There is not a lot you can do to make this dish special, but it is just perfect in its simplicity. As human populations grow, fishing techniques improve, and refrigeration provides a means to transport fish over greater distances, we have solved that problem. The dressing is a bright and fresh mix with only the good, healthy fat found in olive oil.
Add more cracked red pepper if you like it spicy. This is a regular in my weekday rotation because of how easy it is to make. Coupled with a nice grilled or baked fish, this is a perfect meal with high protein that is low in fat and net carbs.
These personalized chalkboard menus were made for us by our dear friend Stacy! Check out her instagram thetangledsea. Americans fall into three camps with seafood: 1. They love it. They will eat it but are afraid to cook it at home. They outright refuse to try it. Learn More. Want to Learn more about our icon system? Check it out. Need a chalkboard menu?Sherpa is a Monte Carlo event generator for the Simulation of High-Energy Reactions of PArticles in lepton-lepton, lepton-photon, photon-photon, lepton-hadron and hadron-hadron collisions.
This document provides information to help users understand and apply Sherpa for their physics studies. The event generator is introduced, in broad terms, and the installation and running of the program are outlined.
The various options and parameters specifying the program are compiled, and their meanings are explained. This document does not aim at giving a complete description of the physics content of Sherpa. To this end, the authors refer the reader to the original publication, [ Gle08b ]. Sherpa [ Gle08b ] is a Monte Carlo event generator that provides complete hadronic final states in simulations of high-energy particle collisions.
The produced events may be passed into detector simulations used by the various experiments.
Sherpa Manual Version 2.1.1
The list of physics processes that come with Sherpa covers particle production at tree level in the Standard Model and in models beyond the Standard Model: The complete set of Feynman rules for the MSSM has been implemented according to [ Ros89 ], [ Ros95 ], including general mixing matrices for inter-generational squark and slepton mixing.
Furthermore, anomalous gauge couplings [ Hag86 ], a model with an extended Higgs sector [ Ded08 ], and a version of the Two-Higgs Doublet Model are available. This feature enables Sherpa to be used as a cross-section integrator and parton-level event generator as well. This aspect has been extensively tested, see e. As a second key feature of Sherpa the program provides an implementation of the merging approaches of [ Hoe09 ] and [ Geh12 ], [ Hoe12a ].
These algorithms yield improved descriptions of multijet production processes, which copiously appear at lepton-hadron colliders like HERA [ Car09 ], or hadron-hadron colliders like the Tevatron and the LHC, [ Kra04 ], [ Kra05 ], [ Gle05 ], [ Hoe09a ]. This manual contains all information necessary to get started with Sherpa as quickly as possible.
It lists options and switches of interest for steering the simulation of various physics aspects of the collision. It does not describe the physics simulated by Sherpa or the underlying structure of the program. Many external codes can be linked with Sherpa. This manual explains how to do this, but it does not contain a description of the external programs.
You are encouraged to read their corresponding documentations, which are referenced in the text. If you use external programs with Sherpa, you are encouraged to cite them accordingly.Some are extraordinarily colorful and equally animated. Others are drab or transparent and hard to see.
Some are active cleaners. Others are scavengers. Some have rather large, sophisticated eyes. Others are blind.
Many live in association with the seafloor and only swim occasionally, and some live in association with other animals such as anemones and sponges.
Others spend their entire lives swimming in the open sea.
Small Critters With a Big Story to Tell: The Shrimps
Some are smaller than your smallest fingernail. Others grow to a length of at least 26 inches 66 cm. Some are quite noisy. Others silent. Shrimps occur in a variety of freshwater and marine habitats including lakes, rice paddies, coral reef communities, rocky reef communities of temperate and subtropical seas, caves and in ocean waters as deep as three miles five km below the surface.
With so many species living in a variety of habitats, it should not be surprising that shrimps are a rather diverse group of animals. Larger species are often called prawns. While some shrimps serve in vital roles as cleaners that help rid host fishes of external parasites and fungi, bacteria and dead tissue found on the skin, many other species are active scavengers.
A number of open-water shrimps feed on tiny animals collectively known as zooplankton and, in turn, they are pursued by myriad fishes. To avoid predators, most open-ocean species migrate daily between the surface where they feed at night and deeper water during the day. Both freshwater and saltwater shrimps are readily preyed upon by many creatures, especially fishes and seabirds. As divers many of us first encounter shrimps when we see them crawling on the face of or even into the mouth of a grouper or moray eel as the shrimp provides its cleaning services to the host fish.
We also see them, or at least we see their bright, highly reflective eyes shining in the distance, at night as they reflect the beams from our dive lights. However, in many instances when light-carrying night divers approach, the shrimps dart away or quickly bury themselves in the substrate.
But just when you are about to give up, thinking that you will never get a good look from close range, a cooperative shrimp sits perfectly still showing off its dazzling colors and handsome body. In other scenarios we see shrimps that seem to be trying to make their presence known. If you miss the sounds when you are underwater, you often hear them echoing off the hull of your boat as you lay your head on your pillow at the end of a diving day.
A Malaysian crinoid shrimp blends in with its host crinoid. Photo by Marty Snyderman.
Collectivity from interference
They are members of the class Crustacea. In addition to true shrimps, a list of crustaceans includes lobsters, crabs, barnacles, copepods, isopods, amphipods and stomatopods. Like all crustaceans, shrimps display bilateral symmetry, and have jointed appendages and a hard exoskeleton.
Many possess large claws that are used in defense and for capturing and gathering food. Living inside of a hard shell has its protective advantages, but the lifestyle is also fraught with problems. Growth is difficult and can be dangerous as shrimps and other crustaceans must crawl out of their restrictive shells to grow. Shrimps have elongated bodies that are typically divided into two major sections.In a six month mesocosm tank experiment, hypotheses were tested concerning the role of benthopelagic mysid shrimps Mysidacea in the near-bottom food web of the Bothnian Sea, in the northern Baltic Sea.
The first hypothesis tested was that the mysids interact, through predation, with benthic deposit-feeding Monoporeia affinis amphipods. A second hypothesis tested was that the sediment type is important for the overwintering success of the mysids. Changes in abundance and mass were recorded for M. Despite the fact that newborn M. The biomass of mysids was slightly higher in the muddy clay than in the sand tanks, and the mechanism behind this substrate effect is discussed. A third hypothesis, that the mysids interact with near-bottom zooplankton, was investigated.
The tanks were continually supplied with in situ near-bottom sea-water containing a seminatural assemblage of near-bottom plankton. As a result of mysid predation, tanks with mysids had lower abundance and biomass of cyclopoid copepods than tanks without mysids. Thus, the major interaction found was predation on near-bottom zooplankton by mysids and it is suggested that this interaction could potentially be an important food link, especially during periods with low food availability in the pelagic system.
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