680 research outputs found
Development of a bedrest muscle stress apparatus
In attempting further to define the deleterious effects of spaceflight on the human body, measurement systems and techniques were devised to determine the loss of skeletal muscle strength and tone as a result of spaceflight exposure. In order to determine how the muscle degradation process progresses with time during nonuse, a system for measuring muscle stress during bedrest was developed. The Bedrest Muscle Stress Apparatus is configured to slip snugly over the foot board of a standard hospital bed. Data collected with this device correlated well with pre- and post-bedrest data collected with the original skeletal muscle stress apparatus
Germacrene D Cyclization: An Ab Initio Investigation
Essential oils that contain large concentrations of germacrene D are typically accompanied by cadinane sesquiterpenoids. The acid-catalyzed cyclization of germacrene D to give cadinane and selinane sesquiterpenes has been computationally investigated using both density functional (B3LYP/6-31G*) and post Hartree-Fock (MP2/6-31G* *) ab initio methods. The calculated energies are in general agreement with experimentally observed product distributions, both from acid-catalyzed cyclizations as well as distribution of the compounds in essential oils
Minimal Seesaw as an Ultraviolet Insensitive Cure for the Problems of Anomaly Mediation
We show that an intermediate scale supersymmetric left-right seesaw scenario
with automatic R-parity conservation can cure the problem of tachyonic slepton
masses that arises when supersymmetry is broken by anomaly mediation, while
preserving ultraviolet insensitivity. The reason for this is the existence of
light B - L = 2 higgses with yukawa couplings to the charged leptons. We find
these theories to have distinct predictions compared to the usual mSUGRA and
gauge mediated models as well as the minimal AMSB models. Such predictions
include a condensed gaugino mass spectrum and possibly a correspondingly
condensed sfermion spectrum.Comment: 19 pages, 1 figur
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Chemotyping and Determination of Antimicrobial, Insecticidal, and Cytotoxic Properties of Wild-Grown Cannabis sativa from Nepal
Cannabis sativa was collected from a wildgrowing population in Biratnagar, Nepal. The essential oil was obtained by hydrodistillation and analyzed by gas chromatography – mass spectrometry. A total of 107 constituents were identified in the oil accounting for 94.2% of the composition. This Nepalese chemotype is characterized by a predominance of sesquiterpenoids (68.1%) dominated by (E)-caryophyllene (20.4%), α-humulene (7.0%), and α-bisabolol (5.8%), but a paucity of monoterpene hydrocarbons (0.9%). In particular, neither myrcene nor terpinolene were detected. The oil in the Nepalese Cannabis plants did contain small amounts of cannabidiol (1.6%), cannabichromene (0.2%) and Δ9-tetrahydrocannabinol (0.4%). The essential oil from Nepalese Cannabis sativa was screened for antimicrobial, cytotoxic, larvicidal, and insecticidal activity, and it appears as though C. sativa is relatively non-toxic
Running with Triplets: How Slepton Masses Change With Doubly-Charged Higgses
We examine the slepton masses of SUSYLR models and how they change due the
presence of light-doubly charged higgs bosons. We discover that the measurement
of the slepton masses could bound and even predict the value of the third
generation Yukawa coupling of leptons to the SU(2)_R Triplets. We also consider
the unification prospects for this model with the addition of left-handed, B -
L = 0 triplets--a model we call the Triplet Extended Supersymmetric Standard
Model (TESSM). Finally, we discuss the changes in the slepton masses due to the
presence of the SU(2)_L triplets.Comment: 20 pages, 6 figures, 4 table
Effect of the sample geometry on the second magnetization peak in single crystalline BaKBiO thick film
Magnetization hysteresis loop measurements performed on a single
crystalline BaKBiO superconducting thick film reveal
pronounced sample geometry dependence of the "second magnetization peak" (SMP),
i.e. a maximum in the width of occurring at the field .
In particular, it is found that the SMP vanishes decreasing the film dimension.
We argue that the observed sample geometry dependence of the SMP cannot be
accounted for by models which assume a vortex pinning enhancement as the origin
of the SMP. Our results can be understood considering the thermomagnetic
instability effect and/or non-uniform current distribution at
in large enough samples.Comment: 8 pages 3 figure
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Tabebuia bahamensis: A Major Source of Pharmacologically Important Ursolic Acid
Leaves of Tabebuia bahamensis, collected on Abaco Island, Bahamas, were dried and extracted with dichloromethane to yield a crude extract. Using preparative flash column chromatography on silica gel, enabled the isolation of ursolic acid with an excellent yield of 2.06 percent based on the mass of dry leaves. Both the crude leaf extract and ursolic acid produced selective in-vitro cytotoxic activity on tumor cells from human mammary and bladder tissue. Ursolic acid also demonstrated antibacterial activity against Staphylococcus aureus
Antiprotozoal Activity of Essential Oils
In the present scenario of protozoal infections, new drugs are urgently needed to treat and control infections such as malaria, sleeping sickness, Chagas disease, leishmaniasis and intestinal infections, which affect millions of people each year. In this review, we are focusing on articles related to antiprotozoal essential oils extracted from plants that have been published during the last 20 years. The data analyzed indicate that essential oils could be promising antiprotozoal agents, opening perspectives to the discovery of more effective drugs of vegetal origin for the treatment of diseases caused by protozoa
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