Dark Matter Research Boston

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KEY TOPICS

In this talk I propose a new alternative to the Cold Dark Matter scenario, in which the dark sector contains a dark matter particle charged under the Standard Model SU(2) gauge group and also charged under an additional SU(N) dark gauge group.(More…)

POSSIBLY USEFUL

I focus on the case in which the dark gauge group has a coupling constant much smaller than the Standard Model gauge couplings.(More…)

RANKED SELECTED SOURCES

KEY TOPICS

In this talk I propose a new alternative to the Cold Dark Matter scenario, in which the dark sector contains a dark matter particle charged under the Standard Model SU(2) gauge group and also charged under an additional SU(N) dark gauge group. [1] After this I discuss the effects of the dark gauge bosons on the Cosmic Microwave Background and also show that the interactions between dark matter and the dark gauge bosons give rise to a new regime in the evolution of dark matter overdensities. [1]

There are many deviations from this standard paradigm, which lead to different predictions for the interactions of dark matter we can observe in direct and indirect detection experiments. [2] Peim said, his group explored the implications that these results had on direct detection dark matter experiments. [3] Many experiments exist that are looking to find dark matter, but no convincing evidence of direct detection has been agreed upon by the scientific community, Gilchriese said. [4] The third experiment detects another kind of particle, axions, which are also theorized to make up dark matter. [4] One possibility is that dark matter lives in a “hidden sector” of nature, namely as part of a collection of particles that interact very feebly with the standard model. [2] In one paper, my collaborators and I proposed extending the Minimal Supersymmetric Standard Model by a hidden sector field that includes both fermionic and baryonic stable particles as dark matter candidates, which was the first in literature to do so.” [3] “We discussed several candidate models for asymmetric dark matter using a variety of operators constructed from Standard Model fields, which transfers the asymmetry to the dark matter sector at thermal equilibrium in the early universe. [3] This month, three new experiments take significant steps in the hunt for dark matter, the elusive substance that appears to make up more than a quarter of the universe, but interacts very rarely with the matter that makes up our world. [5] One possibility is the “axion portal”, where dark matter and ordinary matter interact via a very light “axion” particle. [2] In support of the recent funding opportunities, Figueroa-Feliciano, Nelson, and Rybka will also answer questions about the next generation of dark matter experiments in a live Google Hangout on Nov. 20 from 12:00-12:30 p.m. Members of the public may submit questions ahead of and during the webcast by emailing info@kavlifoundation.org or by using the hashtag #KavliLive on Twitter or Google Plus. [5] From left: Harry Nelson, Enectali Figueroa-Feliciano, and Gray Rybka will answer questions about the next generation of dark matter experiments in a live Google Hangout on Nov. 20. [5] Called the LUX-ZEPLIN, or LZ, experiment, the project involves the creation of an ultra-sensitive underground dark matter detector and will likely be allocated about $25 million to $30 million from the U.S. Department of Energy and the National Science Foundation, according to Harry Nelson, spokesperson for the experiment. [4] Emphasis will be given to all three experimental routes to discovering dark matter, across the intensity/precision frontier (direct detection), the energy frontier (colliders) and the cosmic frontier (indirect detection). [6] Professor Peter Fisher’s main activities are the experimental detection of dark matter using a new kind of detector with directional sensitivity and understanding the weak interactions using tau decays detector with the BaBar detector. [7] A key question is whether dark matter might have other interactions with the standard model. [2] One of key questions about dark matter is how it is produced in the early universe. [2] Nelson said dark matter exists in the universe “beyond all reasonable doubt.” [4] Hidden sectors appear in many supersymmetric scenarios, and hidden sector dark matter can have an interesting effect on the measured cosmic ray spectrum. [2] Dark matter is five times more abundant than ordinary (baryonic) matter, but very little is known about dark matter or its properties. [2]

Some theories of dark matter posit that it is part of a “dark sector” that is sort of like a mirror of the regular universe — in other words, that it contains dark versions of regular matter particles, like dark photons and dark electrons. [8] Dark matter may not be part of a “dark sector” of particles that mirrors regular matter, as some theories suggest, say scientists studying collisions of galaxy clusters. [8] The CERN scientists would hope to detect any dark matter by noticing that some energy was missing after the collision, which would betray the existence of such a particle, Malgeri said. [9] “The gravitational detection of dark matter tells you very little about the particle behavior of the dark matter,” says Matthew Walker, assistant professor of physics and a member of Carnegie Mellon’s McWilliams Center for Cosmology. [10] “But now we may have a non-gravitational detection that shows dark matter behaving like a particle, which is a holy grail of sorts.” [10] “Chances are that dark matter is not made up of dark protons interacting with dark protons, and chances are, there is not a mirror universe out there with these dark particles,” Harvey said. [8] That’s why dwarf galaxies are important in the hunt for the dark matter particle. [10] Scientists know that dark matter exists because it exerts gravitational effects on visible matter, which explains the observed rotation of galaxies and galaxy clusters as well as fluctuations in the cosmic microwave background. [10] Scientists have tried to use these galaxy cluster crashes to study dark matter for decades, but improved techniques for observing the different components of those mergers has inspired a revival, he said. [8] Mr Rampino reasoned that if, as some scientists believe, there is a thin disk of dark matter running horizontally through our Milky Way galaxy, then our solar system moving around the galactic center, may have occasionally bobbed up and down through it. [11] The implications of the new finding go beyond galaxy mergers: They tell scientists something about what dark matter might be made of. [8] Modern theories suggests dark matter makes up a substantial portion of the mass of our universe, and the inner part of our galaxy, where our solar system resides, is thought to contain it. [11] To do this, Harvey and his colleagues at the University of Edinburgh, where Harvey did his PhD work, looked at collisions among entire clusters of galaxies, where as much as 90 percent of the mass involved in the collision is dark matter, according to a statement from the Swiss Federal Institute of Technology Lausanne. [8] “If we measure the dark matter, and should it lie where the galaxies are, we know the dark matter is completely collisionless, and doesn’t interact with itself at all,” Harvey said. [8] Harvey and his colleagues showed that dark matter clearly doesn’t interact with itself the way the gas does; more specifically, it interacts with itself less than protons interact with one another. [8] A leading theory suggests that dark matter particles are WIMPs–Weakly Interacting Massive Particles. [10] An image of galaxy merger A370, overlaid with a model of the dark matter present. [8] A newly discovered dwarf galaxy orbiting the Milky Way appears to be radiating gamma rays–a sign that dark matter may be lurking at the galaxy’s center. [10] Now, that DNA dark matter could be accessed using Cas9, allowing scientists to document which non-translated genes can be activated in tandem to influence gene expression. [12] “As well as being important on the largest scales, dark matter may have a direct effect on life on Earth.” [11]

The effect of this gravitational pull permits astronomers to measure where dark matter is, and they thus know that in the Milky Way it is concentrated, like atomic matter, in the disc. [13] The solution could lie in baryonic physics: Recent numerical simulations and analytical models suggest that gravitational potential fluctuations tied to efficient supernova feedback can flatten the central cusps of halos in massive galaxies, and a combination of feedback and low star formation efficiency could explain why most of the dark matter subhalos orbiting the Milky Way do not host visible galaxies. [14] The cold dark matter (CDM) cosmological model has been remarkably successful in explaining cosmic structure over an enormous span of redshift, but it has faced persistent challenges from observations that probe the innermost regions of dark matter halos and the properties of the Milky Way?s dwarf galaxy satellites. [14] To do this, they construct a model galaxy with the large dark matter density necessary for black hole formation. [15] Elastic scattering from strong dark matter self-interactions can alter predicted halo mass profiles, leading to good agreement with observations across a wide range of galaxy mass. [14] In the core, the dark matter particles can accumulate to push the neutron star above its critical mass. [15] I mean “scattering off” as a colloquial way to say that dark matter particles need to interact with nucleons in the neutron star. [15] Dark matter particles may scatter off the surface of neutron stars, heat up and sink to the cores. [15] Our best guess is that dark matter is a new type of particle, but its mass and properties are highly uncertain. [15] In this dissertation, a low energy theory approach is applied to the studies of Dark Matter direct detection experiments and two-dimensional Quantum Chromodynamics (QCD) spectra. [16] We build a general framework of non-relativistic effective field theory of Dark Matter direct detection using non-relativistic operators. [16] Dark matter preying upon neutron stars and belching the remnants our way is certainly an exciting theory, but, for now, the source of FRBs remains a mystery. [15] This study also finds that FRBs should be clumped near the centers of galaxies, where the dark matter concentration is high enough to facilitate neutron star collapse. [15] The broad and continued accumulation of GWAS data, with the same pattern of distribution in non-coding regions, highlights the importance of pervasive transcription and dark matter RNA. [17] These questions include the nature of dark matter, the origins of the electroweak scale and the cosmological constant as well as the quantum nature of gravity. [18]

Even if the experts are right about that, it still leaves the big question: are these excesses signals of previously unknown astrophysical phenomena, or are they signals of decaying or annihilating dark matter particles? New astrophysics would be interesting too, but probably not Nobel-worthy, as dark matter would be. [19] If such a dark sector exists, the best targets for LHC’s experiments (and other experiments, such as APEX or SHiP ) are often not the stable particles that could form dark matter but their unstable friends and associates. [19] If other types of experiments (e.g. LUX or COGENT or Fermi ) detect dark matter itself, they can check whether it shares the same properties as LHC’s new particles. [19] Dark matter particles, like neutrinos, would not be observed directly. [19] Last week I attended the Eighth Harvard-Smithsonian Conference on Theoretical Astrophysics, entitled “Debates on the Nature of Dark Matter”, which brought together leading figures in astronomy, astrophysics, cosmology and particle physics. [19] Everyone one should understand that the arguments in favor of dark matter are by no means limited to the questions of how stars move in galaxies and how galaxies move in galaxy clusters. [19] In the meantime, after Monday’s post, I got a number of interesting questions about dark matter, why most experts are confident it exists, etc. There are many reasons to be confident; it’s not just one argument, but a set of interlocking arguments. [19] In developing an answer, scientists have discovered that the predominant functional unit of the dark matter RNA is vlincRNA, which are the long and abundantly transcribed regions of noncoding RNA. [20] As scientists gain evidence for the functional significance of dark matter RNA in gene expression, they simultaneously realize how much is left to be learned and how important that knowledge can be. [20] By the time the story goes to press, all the modifiers and nuances uttered by the scientists are gone, and all that remains is “LHC looking for dark matter”. [19] Why are these others important? Because if they are produced at the LHC, they may decay in a fashion that is easy to observe easier than dark matter itself, which simply exits the LHC experiments without a trace, and can only be inferred from something recoiling against it. [19] Matters are even further complicated by the fact that this dark matter RNA is composed primarily of very long functional regions. [20]

The much higher energy in round two of LHC experiments could provide enough data to clarify the role of these supersymmetric particles, explaining the actual nature of dark matter in the universe. [21] The institute covered in great detail not only the many parallel threads of evidence for dark matter, but also our current and planned efforts at measuring it, directly (via interactions with underground detectors or by producing it in high energy particle colliders) and indirectly (via high resolution/high cadence astronomical observation and by detection of astrophysical products of dark matter interactions). [22] Experimental particle astrophysics including dark matter detection and precision tests of gravity with lunar laser ranging ( lab website ). [23] There is a theory that dark matter contains “supersymmetric particles” that are partners to all of the other particles that are already known in the Standard Model. [21] That suggests a dark matter density around the solar system of maybe 500-ish GeV per cm^3 (I’m quoting in mass/energy units because we don’t know the mass of a DM particle). [22] Dark Matter is based on the assumption that the stars are in orbit around a central mass (meaning the path is closed). [22] The stars in a galaxy do not follow Keplerian orbits, and would not follow such orbits even in the absence of dark matter. [22] Dark matter has not been observed yet, but according to scientists, it should be present to explain huge gravitational effects in the universe. [24] I developed a new First-Year Seminar course called Einstein and the Dark Universe (PHYS100/ASTR110) in which students uncover the astrophysical evidence for dark matter and dark energy through analyses of archival data sets as well as their own radio telescope observations. [23] Image credit: CMB pattern for a universe with normal matter only compared do our own, which includes dark matter and dark energy. [22] Theoretical physicists have believed for some time that invisible dark matter makes up most of the universe. [21] In order to resolve the observational constraints (virial velocities in galaxy clusters, graviational lensing, galactic rotation curves), the amount of dark matter needs to be about five times that of normal, baryonic matter, when measured on scales of galaxies or larger. [22] They don’t square with the assertion that the total mass of dark matter is five times the mass of baryonic matter. [22] According to Biology Professor Michael Rampino, of New York University, Earth travels through areas of concentrated dark matter at certain times. [24] If the dark matter had enough other interactions with normal matter that we could detect it now, for example, then those interactions would lead to an effective “friction”, slowing down galaxies in a way which is not observed. [22] If such a thing is reasonable, would it be possible that matter that exists in such additional dimensions could be the explanation of dark matter? After all, under this idea, gravity is the only force that interacts with the additional dimensions beyond the three familiar ones. [22] “If instead a large fraction of the galaxy?s mass resided in a diffuse dark matter “halo? that extended well beyond the edges of the luminous matter, the observed galactic rotation curves could be explained.” [22] Dark matter was “invented” as a hypothesis to “rescue” graviational theory (both GR and simple Newtonian gravity) from its apparent violation by galaxy clusters and galactic rotation. [22]

” Previous studies of colliding galaxy clusters have shown that dark matter barely interacts with anything. [25] PandaX is the first dark matter experiment in China that deploys more than one hundred kilograms of xenon as a detector; the project is designed to monitor potential collisions between xenon nucleons and weakly interactive massive particles, hypothesized candidates for dark matter. [26] If confirmed, dark matter particles would extend understanding of the fundamental building blocks of nature beyond the Standard Model of particle physics, and would provide support for theories on supersymmetry and extra dimensions of space-time. [26] “Weakly interacting massive particles (WIMPs), a particular class of dark matter candidates, are interesting in particle physics and can be studied in colliders indirect and direct detection experiments.” [26] Scientists are pretty sure dark matter particles, or most of them, are WIMPs ( Weakly Interacting Massive Particles ). [25] ” Dark matter is the invisible ‘web’ that holds galaxies together; by watching how clumps of it shift over time, scientists hope eventually to quantify dark energy – the even more mysterious force that is pushing the cosmos apart. [25] They are mapping the universe, tracing the effects of dark matter and dark energy: or whatever is pulling and apparently pushing galaxies and galactic clusters into position. [25] I’m reasonably sure that dark matter, and dark energy are real: based on what we’ve been learning about the universe. [25] Missing word? “the better dark matter and dark energy look explanations for what scientists observe.” [25] Unlike phlogiston, however the more data they collect, the better dark matter and dark energy look as explanations for what scientists observe. [25] Despite what the second paragraph says, these scientists didn’t observe “fibres of dark matter, studded with galaxies,” they mapped gravity lensing. [25] Although saying that dark matter “is the invisible ‘web’ that holds galaxies together” may be true the last I checked, scientists still weren’t that certain. [25] Other scientists, studying galaxies about 1,400,000,000 light years away, collected and analyzed data that may help us understand dark matter. [25] Dark matter halos existing around visible galaxies are essential to studies of galaxy formation and evolution. [27] ” Incredible detail is required to detect dark matter, based purely on the way it warps the light from very distant galaxies [25] The PandaX experiment to date has collected about 4 million raw events; only about ten thousand events fell into the energy region of interest for dark matter. [26] The results enable astronomers to predict how dark matter halos behave in non-virialized regions of space and deepen our understanding of galaxy formation. [27] We didn’t realized that dark matter might exist until we started measuring things larger than star systems and smaller than atoms, though: so there’s a very great deal left to learn. [25] “Direct positive detection of WIMPs using ultra-low background detectors in deep underground laboratories would provide convincing evidence of dark matter in our solar system and allow the probing of fundamental properties of WIMPs,” they add in the new study. [26]

POSSIBLY USEFUL

I focus on the case in which the dark gauge group has a coupling constant much smaller than the Standard Model gauge couplings. [1] At the same time the discovery of many materials that show strong correlation effects is forcing condensed matter physicists to look for explanations that go beyond the standard paradigms, including emergent gauge fields, non-Fermi liquids and topological phases. [6] The manipulation of ultra-cold atoms and molecules allowed for the creation of several ultra-low-temperature quantum matter systems with an unprecedented degree of control over interaction strength; atom/molecule density; magnetization; artificial gauge and spin-orbit fields; lattice strength, structure, and dimensionality. [6]

Halo CDM can’t be WIMPs, otherwise CDM would also be found in the galactic bulge and in globular clusters (cuspy halo problem), so it has to be CDM baryonic matter that converts to luminous matter in high density regions of galaxies, and I spy invisible, primordial baryonic-matter reservoirs that are more massive and more diffuse than MACROs and whose evaporation creates giant molecular clouds in the spiral arms. [4]

All of those stars, galaxies, gas and dust make up only about 10 to 15 percent of the matter in the universe. [8] Scientists know it’s there because it interacts gravitationally with visible matter and radiation. [11] GENEVA The Large Hadron Collider (LHC) will start smashing particles together at unprecedented speed on Wednesday, churning out data for the first time in more than two years that scientists hope might help crack the mystery of “dark matter”. [9]

CERN’s first great triumph was the 2012 discovery of the enigmatic and long elusive Higgs boson, the subatomic “God particle” that imparts mass to matter and whose proved existence was crucial to bolstering principles of physics. [28]

The galaxy, named Reticulum 2, was identified recently in the data of the Dark Energy Survey, an experiment that maps the southern sky to understand the accelerated expansion of the universe. [10] “Dark matter particles may scatter off the surface of neutron stars, heat up and sink to the cores.” [15]

This theory provides tight constraints on dark matter’s interaction rate with baryonic matter. [15]

In his latest paper, just published in the Monthly Notices of the Royal Astronomical Society, Dr Rampino speculates that the real culprit may be not stars, but dark matter–and that this might explain the volcanism as well. [13] The small-scale conflicts could be evidence of more complex physics in the dark sector itself. [14]

It is more than five times as abundant as the familiar matter that atoms are made of, but tends to interact with atomic matter only through gravity. [13]

Well, a restart of such a machine, after two years of upgrades, is not a simple matter, and perhaps we should say that the LHC has “begun to restart”. [19] A dark sector/hidden valley would involve several types of particles that interact with one another, but interact hardly at all with anything that we and our surroundings are made from. [19] Its existence is still not 100% certain, but if it exists, it is exceedingly dark, both in the usual sense it doesn’t emit light or reflect light or scatter light and in a more general sense it doesn’t interact much, in any way, with ordinary stuff, like tables or floors or planets or humans. [19]

New low-mass particles to which the Higgs particle can perhaps decay could easily have been missed, if they interact much more weakly with ordinary matter than do the Z particle, top quark, bottom quark, muon, etc. [19] I’ve finished an article describing how we can, with current and with future Large Hadron Collider data, look for a Higgs particle decaying to two new spin one particles, somewhat similar to the Z particle, but with smaller mass and much weaker interactions with ordinary matter. [19] New particles may be discovered not because we produce them directly in ordinary matter collisions, but because, as in the above figure, we first produce a Higgs particle in proton-proton collisions at the LHC, and the Higgs may then in turn decay to them. [19]

He teaches writing at Bunker Hill Community College in Boston and Endicott College in Beverly, Mass. He is the arts/editor of The Somerville News, and for the past twenty years has run poetry groups at McLean Hospital in Belmont, Mass. His poetry and prose have appeared in the Bay State Banner, The Boston Globe, The Boston Globe Magazine, Rattle, Endicott Review, Long Island Quarterly, Toronto Quarterly and many others. [29] J.L. Morin ( Lecturer at Boston University/ Library Review) “That’s a lovely blog you’ve got there, Doug Holder.” ( Sherill Tippins–“Inside the Dream Palace: The Life and Times of New York’s Legendary Chelsea Hotel.”) ” I love your introduction, and fervently hope that Somerville never meets anything like the Chelsea Hotel’s fate. [29]

Seminal texts like Mrs. Lincoln’s Boston Cook Book and Fannie Farmer’s Boston Cooking-School Cook Book, as well as newer works like Sandra Oliver’s Saltwater Foodways, became a foundation for Sheehan’s approach to classic New England cuisine, albeit with modern techniques and ingredients. [30] While the Standard Model has worked quite well in predicting the basic building blocks of matter, the theory is incomplete. [21] Astrophysical observations have revealed that the majority (~80%) of matter in the Universe falls outside of the Standard Model of particle physics. [23]

This cosmic soup at the start of the Big Bang was dominated by fundamental bits of matter called quarks, and gluons that carry a strong force that “glues” quarks together into things that are familiar to us like protons and neutrons. [21]

There is considerable evidence today that elliptical galaxies have little or no “Dark Mass” or, peculiar velocities attributed to “Dark Matter”. [22] “Dark matter interacts with its surroundings significantly less frequently than ordinary matter. [22] @kat #32: It was called “dark matter” because it doesn’t interact with light at all. [22] Recently, there?s been a call to go back into the biodiversity mines, this time looking for microbial “dark matter” the ~99% of bugs that we know are there because of high-throughput sequencing, but that cannot be cultured in the lab. [31] @Roy Lofquist #12: “Dark Matter should be denser in the vicinity of concentrations of ordinary matter because gravitation.” [22]

“But if these “dark sector? particles have mass, they will interact with the field associated with the Higgs boson.” [21] As in Fig. 3, dark outlines in either group indicate a TBI by any mechanism (blast-induced or otherwise) during that participant?s lifetime, the participants with moderate or severe TBI in their lifetime ( n 6) were all in the blast-exposed group and are indicated with a black X, and dotted lines show the 95% confidence interval for an observation based on the quadratic model. [32]

It may also “explain” Dark energy, as these dimensions are scrolled up tighter and tighter as the universe expands, leaving less and less room for interaction to take place. [22]

The hypothesis for a blast exposure age interaction on white matter integrity is supported by the significant association between white matter integrity (i.e. fractional anisotropy) and YB-blast in a group of blast-exposed veterans that is absent from a group of age- and PTSD severity-matched YB-blast-adjusted blast-unexposed peers in some of the same regions. [32] The results of this study are cross-sectional and do not demonstrate changes in fractional anisotropy, apparent diffusion coefficient or radial diffusivity in any individual, only that in the given sample of TRACTS participants there is the observation that a group of veterans with blast exposure and a group without exposure show a difference in fractional anisotropy association with age in several regions throughout the cerebral white matter. [32]

Evidence supporting the utility of DTI to specifically study the effects of blast on white matter integrity is corroborated by a recent study in which Taber et al. (2015) report spatially dispersed regions of significantly lower fractional anisotropy in blast-exposed ( n 29, 23 with TBI diagnosis) compared with blast-unexposed veterans ( n 16). [32] Despite these limitations, a number of studies have demonstrated the utility of DTI for examining the effects of TBI and blast on white matter integrity in both veteran and non-veteran populations ( Kraus et al., 2007 ; Kennedy et al., 2009 ; Kinnunen et al., 2011, 2012 ; Davenport et al., 2012 ; Wada et al., 2012 ; Bazarian et al., 2013 ; Morey et al., 2013 ; Tremblay et al., 2014 ; Taber et al., 2015 ). [32] Although a causative link has not been established, both the civilian and military literature on TBI suggest that a history of brain trauma may be associated with enduring changes in brain structures, especially in the cerebral white matter ( Kinnunen et al., 2011 ; Mac Donald et al., 2011, 2014 ; Wada et al., 2012 ; Bazarian et al., 2013 ; Morey et al., 2013 ; Tremblay et al., 2014 ; Taber et al., 2015 ). [32] Some of the changes to white matter are similar to those that have been described as occurring with ageing ( Nomura et al., 1994 ; Courchesne et al., 2000 ; Nusbaum et al., 2001 ; Salat et al., 2005 a, b ; Burzynska et al., 2010 ; Westlye et al., 2010 ; Lebel et al., 2012 ) suggesting that a history of blunt head trauma may exacerbate any pathological burden typically associated with the ageing process. [32]

“Randomise? ( Winkler et al., 2014 ), a non-parametric permutation testing method for statistical analysis that avoids assumptions about the distribution of DTI data, was used to perform voxel-wise analyses of the white matter skeleton and determine the significance level for the contrast of interest in the full model with covariates (clinical/demographic regressors) at every skeleton voxel using 5000 permutations. [32] Motivated by recent results demonstrating a specific effect of close-range blast exposure on brain function ( Robinson et al., 2015 ), the influence of YB-blast on white matter was investigated in an exploratory analysis for a subset of participants, all with close-range blast exposure ( n 76). [32] For individuals with a history of blast exposure, the effect of time since blast exposure on white matter integrity could become an important consideration for determining the appropriate course of treatment and predicting clinical outcomes. [32] Military blast exposure may, therefore, be the primary component responsible for negatively deflecting the trajectory of normal age-associated decline in white matter integrity and this effect may be due to neurodegenerative effects, as suggested by the analysis of time since most severe blast. [32] The effect of a dose response to blast at the regional level emphasizes the potential importance of blast exposure in affecting the integrity of white matter over the lifespan. [32] The regional effect was sensitive to the degree of blast exposure, suggesting a “dose-response? relationship between the number of blast exposures and white matter integrity. [32] The present study used diffusion tensor imaging (DTI) and a cross-sectional design in a veteran sample varying in age from 19 to 62 years to glimpse whether exposure to high intensity blast forces has effects on the integrity of cerebral white matter across the lifespan. [32] The primary finding in this cross-sectional report was that a group of veterans exposed to military-associated blast forces exhibited a significantly more rapid cross-sectional trajectory towards reduced white matter integrity with age compared to a group of veterans without such exposure. [32] At the cross-sectional level, the white matter integrity of blast-exposed veterans exhibited a stronger negative association with age compared to a group without exposure. [32]

Coronal ( A and D ), axial ( B and E ), and sagittal ( C and F ) slices showing the regions and their overlap where a significant ( P < 0.05; corrected) blast exposure age interaction on diffusion parameters was observed, with blast-exposed individuals exhibiting a more rapid cross-sectional age trajectory towards reduced tissue integrity (dilated from white matter skeleton for visualization). [32] Figure 2 Regions throughout cerebral white matter show an interaction between blast exposure and age on diffusion measures. [32]

TBSS analyses revealed a significant blast-exposure age interaction on fractional anisotropy, with the blast-exposed group exhibiting a more negative relationship between fractional anisotropy and age compared to the blast-unexposed group throughout the cerebral white matter. [32] When the current sample of 249 participants was analysed together with TBSS as a single group with no covariates, a substantial portion of the white matter skeleton showed a significant association between fractional anisotropy and age, which is consistent with prior work ( Fig. 3 A and C). [32]

Fractional anisotropy, a scalar metric encoding the directional coherence of water diffusion within a voxel and commonly used as an indicator of white matter integrity ( Basser and Pierpaoli, 1996 ), was the primary diffusion-derived measure employed here to make inferences about white matter microstructure. [32] Effects of chronic mild traumatic brain injury on white matter integrity in Iraq and Afghanistan war veterans. [32] There are limitations to the interpretability of any diffusion-derived parameter as representative of an underlying physiological state or pathology, especially in regions where the parameter?s value incorporates data from either tissue or white matter tracts of differing type (partial volume effects) or orientations (crossing fibre effects) ( Assaf and Pasternak, 2008 ). [32]

Experiencing a blast alone may be sufficient to interrupt and negatively deflect normal ageing trajectories of white matter integrity. [32] The present study used diffusion tensor imaging to investigate whether military-associated blast exposure influences the association between age and white matter tissue structure integrity in a large sample of veterans of the recent conflicts ( n 190 blast-exposed; 59 without exposure) between the ages of 19 and 62 years. [32] White matter integrity and cognition in chronic traumatic brain injury: a diffusion tensor imaging study. [32] White matter damage in Alzheimer’s disease assessed in vivo using diffusion tensor magnetic resonance imaging. [32]

Its constituents interact with baryonic matter via gravity but not with other “particles” of DM. Some how I think even Einstein would have trouble following that train. [22] As far as we know, it does not interact in any other way to any significant degree with either itself or ordinary matter. [22]

TBI and blast history were evaluated by a psychologist using the Boston Assessment of TBI-Lifetime (BAT-L; Fortier et al., 2013 ). [32] His lectures have been sponsored by numerous local chapters of MUFON, BUFORA, and other grass-roots organizations, private groups, schools, universities, libraries, scientific organizations, educational foundations, as well as Cambridge Hospital in Boston (under the sponsorship of Dr. John Mack). [33]

RANKED SELECTED SOURCES
(33 source documents arranged by frequency of occurrence in the above report)

1. (28) Military blast exposure, ageing and white matter integrity | Brain

2. (18) Five Reasons We Think Dark Matter Exists (Synopsis) Starts With A Bang

3. (15) DarkMatter | Of Particular Significance

4. (12) A Catholic Citizen in America: Dark Matter and Energy: New Data, and a Map

5. (10) Dark Matter Probably Isn’t a Mirror Universe, Colliding Galaxies Suggest – Yahoo News

6. (9) The Radio Burp from Dark Matter’s Lunch? | astrobites

7. (7) Will the search for dark matter end with this galaxy? – Futurity

8. (7) research_details [Jesse Thaler]

9. (6) Restarting the Large Hadron Collider: What Will the Research Mean for Science? – US News

10. (5) First dark matter results from underground China lab hosting PandaX-I

11. (5) Berkeley Lab to manage dark matter research project | The Daily Californian