795 research outputs found
Progress on indium and barium single ion optical frequency standards
We report progress on 115In+ and 137Ba+ single ion optical frequency
standards using all solid-state sources. Both are free from quadrupole field
shifts and together enable a search for drift in fundamental constants.Comment: 2 pages, 1 figure, submitted to IEEE/LEOS Summer 2005 Topicals
conference proceeding
The Iowa Homemaker vol.41, no.2
Tips Add Ease In Traveling, Karen Williams, page 4
May Is Raining Roses, Marilynn Bratten, page 6
âInstantâ Palace Is Rare, Sharon Sherman, page 8
Flowers Range from Gardenias to New Glamellias, Anne Collison, page 10
Bells Ring at ISU, Jo Ann Fridley, page 11
Duo Drape Gowns, Anne Miller, Gail Wallen, page 12
Look at Latest, Karen Nielsen, page 1
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Percutaneous Cell Delivery Into the Heart Using Hydrogels Polymerizing In Situ
Heart disease is the leading cause of death in the US. Following an acute myocardial infarction, a fibrous, noncontractile scar develops, and results in congestive heart failure in more than 500,000 patients in the US each year. Muscle regeneration and the induction of new vascular growth to treat ischemic disorders of the heart can have significant therapeutic implications. Early studies in patients with chronic ischemic systolic left ventricular dysfunction (SLVD) using skeletal myoblasts or bone marrow-derived cells report improvement in left ventricular ejection function (LVEF) and clinical status, without notable safety issues. Nonetheless, the efficacy of cell transfer for cardiovascular disease is not established, in part due to a lack of control over cell retention, survival, and function following delivery. We studied the use of biocompatible hydrogels polymerizable in situ as a cell delivery vehicle, to improve cell retention, survival, and function following delivery into the ischemic myocardium. The study was conducted using human bone marrow-derived mesenchymal stem cells and fibrin glue, but the methods are applicable to any human stem cells (adult or embryonic) and a wide range of hydrogels. We first evaluated the utility of several commercially available percutaneous catheters for delivery of viscous cell/hydrogel suspensions. Next we characterized the polymerization kinetics of fibrin glue solutions to define the ranges of concentrations compatible with catheter delivery. We then demonstrate the in vivo effectiveness of this preparation and its ability to increase cell retention and survival in a nude rat model of myocardial infarction
DoubleMod and SingleMod: Simple Randomized Secret-Key Encryption with Bounded Homomorphicity
An encryption relation f Z Z with decryption function f 1 is âgroup-homomorphicâ
if, for any suitable plaintexts x1 and x2, x1+x2 = f 1( f (x1)+f (x2)). It is âring-homomorphicâ
if furthermore x1x2 = f 1( f (x1) f (x2)); it is âfield-homomorphicâ if furthermore 1=x1 =
f 1( f (1=x1)). Such relations would support oblivious processing of encrypted data.
We propose a simple randomized encryption relation f over the integers, called
DoubleMod, which is âbounded ring-homomorphicâ or what some call âsomewhat homomorphic.â
Here, âboundedâ means that the number of additions and multiplications that can
be performed, while not allowing the encrypted values to go out of range, is limited (any
pre-specified bound on the operation-count can be accommodated). Let R be any large integer.
For any plaintext x 2 ZR, DoubleMod encrypts x as f (x) = x + au + bv, where a
and b are randomly chosen integers in some appropriate interval, while (u; v) is the secret
key. Here u > R2 is a large prime and the smallest prime factor of v exceeds u. With
knowledge of the key, but not of a and b, the receiver decrypts the ciphertext by computing
f 1(y) = (y mod v) mod u.
DoubleMod generalizes an independent idea of van Dijk et al. 2010. We present and
refine a new CCA1 chosen-ciphertext attack that finds the secret key of both systems (ours
and van Dijk et al.âs) in linear time in the bit length of the security parameter. Under a
known-plaintext attack, breaking DoubleMod is at most as hard as solving the Approximate
GCD (AGCD) problem. The complexity of AGCD is not known.
We also introduce the SingleMod field-homomorphic cryptosystems. The simplest
SingleMod system based on the integers can be broken trivially. We had hoped, that if
SingleMod is implemented inside non-Euclidean quadratic or higher-order fields with large
discriminants, where GCD computations appear di cult, it may be feasible to achieve a
desired level of security. We show, however, that a variation of our chosen-ciphertext attack
works against SingleMod even in non-Euclidean fields
Concurrent invasions by European starlings (Sturnus vulgaris) suggest selection on shared genomic regions even after genetic bottlenecks
A speciesâ success during the invasion of new areas hinges on an interplay between the demographic processes common to invasions and the specific ecological context of the novel environment. Evolutionary genetic studies of invasive species can investigate how genetic bottlenecks and ecological conditions shape genetic variation in invasions, and our study pairs two invasive populations that are hypothesized to be from the same source population to compare how each population evolved during and after introduction. Invasive European Starlings (Sturnus vulgaris) established populations in both Australia and North America in the 19th century. Here, we compare whole-genome sequences among native and independently introduced European Starling populations to determine how demographic processes interact with rapid evolution to generate similar genetic patterns in these recent and replicated invasions. Demographic models indicate that both invasive populations experienced genetic bottlenecks as expected based on invasion history, and we find that specific genomic regions have differentiated even on this short evolutionary timescale. Despite genetic bottlenecks, we suggest that genetic drift alone cannot explain differentiation in at least two of these regions. The demographic boom intrinsic to many invasions as well as potential inversions may have led to high population-specific differentiation, although the patterns of genetic variation are also consistent with the hypothesis that this infamous and highly mobile invader adapted to novel selection (e.g., extrinsic factors). We use targeted sampling of replicated invasions to identify and evaluate support for multiple, interacting evolutionary mechanisms that lead to differentiation during the invasion process
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