Search

The “Christmas Cave”, a cave in the Qidron Valley near the Dead Sea and Qumran, has yielded a complex collection of plant-derived rope and fabric artifacts. Using polymerase chain reaction (PCR) to amplify DNA of the samples, we estimated the sizes and determined restriction patterns and base sequences of chloroplast genes, primarily rbcL (gene for the large subunit of ribulose bisphosphate carboxylase). DNA was successfully extracted from all samples, but was limited to sizes of approximately 200-300 base pairs. As expected, the DNA extracted from the samples was identified as coming primarily from flax (Linum usitatissamum L.), but two samples had a significant fraction, and all samples had at least a trace, of hemp (Cannabis sativa L.) DNA. Artifacts from the Christmas Cave were thought to date from Roman times, but it was thought possible that some could be much older. Accelerator mass spectrometry (AMS)-based 14C dating confirmed that the samples contained representatives from both the Roman and Chalcolithic periods. This paper provides a synthesis of DNA, isotope, and literary analysis to illuminate textile history at the Christmas Cave site.

The repetitive and highly structured domestic architecture of Catalhoyuk is a distinctive feature of this important Neolithic settlement. At the very end of the sequence, however, excavations on the surface of the East Mound reveal changes in household construction and burial chambers. Bayesian analysis of 56AMS radiocarbon dates from these layers allow the date and pace of these changes to be established in detail. Settlement activity on the East Mound ceased just after 6000 cal BC, and was followed by the cessation of Neolithic burial activity a few decades later. Keywords: Catalhoyuk, Late Neolithic, chronology, Bayesian statistics, pebble floors, burial chambers, households, Introduction The famous site of Catalhoyuk in central Anatolia (32:49:4IN, 37:40:0IE) is made up of two distinct tells, the eastern of which includes over 19m of Neolithic deposits. Excavations were [...]

Rotary biomolecular machines rely on highly symmetric supramolecular structures with rotating units that operate within a densely packed frame of reference, stator, embedded within relatively rigid membranes. The most notable examples are the enzyme FoF1 ATP synthase and the bacterial flagellum, which undergo rotation in steps determined by the symmetries of their rotators and rotating units. Speculating that a precise control of rotational dynamics in rigid environments will be essential for the development of artificial molecular machines, we analyzed the relation between rotational symmetry order and equilibrium rotational dynamics in a set of crystalline molecular gyroscopes with rotators having axial symmetry that ranges from two- to fivefold. The site exchange frequency for these molecules in their closely related crystals at ambient temperature varies by several orders of magnitude, up to ca. 4.46 x [10.sup.8] [s.sup.-1]. solid-state NMR | line shape analysis | spin-lattice relaxation | molecular design | crystal engineering doi/ 10.1073/pnas.1008213107

Previous [sup.14]C determinations obtained on two segments of a single mastodon bone recovered from Monte Verde, Chile, were highly discordant, differing by more than 5,000 years. Because of the significance of this site in discussions concerning the earliest peopling of the Western Hemisphere' additional [sup.14]C and new [δ.sup.13]C values have been obtained on organic fractions isolated from both segments. The constituent amino acid profiles indicate that both bone segments retain significant amounts of protein (mostly collagen) residues. Four accelerator mass spectrometry-based [sup.14]C values obtained on total amino acids and ultrafiltered gelatin fractions--two from each segment--are statistically identical and indicate an age of 12,460 (± 30) BP for the mastodon. This value is concordant with [sup.14]C values obtained on other culturally affiliated organics associated with the MV-II levels at this site. Anteriormente, las determinaciones [sup.14]C obtenidas de dos segmentos de un solo hueso de mastodonte recolectado del deposito arqueologico en Monte Verde, Chile, no correspondian, registrando una diferencia de mas de 5,000 anos. Debido a la importancia de este sitio en el dialogo sobre el poblamiento del nuevo mundo, han sido analizadas muestras adicionales de los mismos segmentos de hueso. Los valores de [sup.14]C y [δ.sup.13]C son derivados de fracciones organicas aislados de ambos segmentos. Los perfiles de aminoacidos indican que ambos segmentos guardaron cantidades significativos de proteina (la mayoria en forma de colageno) residual. Cuatro valores [sup.14]C (AMS) obtenidos de las dos fracciones aminoacidos total y gelatina ultrafiltrada--dos de cada segmento--son identicos, segun las estadisticas, e indican una edad de 12,460 (± 30) anos AP (antes presente) para el mastodonte. Este valor es consistente con los valores de [sup.14]C obtenidos en otros materiales organicos culturalmente asociados con las capas MV-II del sitio., Beginning in 1976, excavations at the Monte Verde site in the forested Lake District of south-central Chile recovered a wide-ranging assemblage of materials from stratified contexts (Dillehay 1989, 1997a). Various [...]

The incorporation of micronutrients into synthetic hydroxyapatite (SHA) is proposed for slow release of these nutrients to crops in the National Aeronautics and Space Administration's (NASA's) Advanced Life Support (ALS) program for Lunar or Martian outposts. Solid state [sup.31]P nuclear magnetic resonance (NMR) was utilized to examine the paramagnetic effects of [Fe.sup.3+], [Mn.sup.2+], and [Cu.sup.2+] to determine if they were incorporated into the SHA structure. Separate [Fe.sup.3+], [Mn.sup.2+], and [Cu.sup.2+] containing SHA materials along with a transition metal free SHA (pure-SHA) were synthesized using a precipitation method. The proximity (

Because xenon NMR is highly sensitive to the local environment, laser-polarized xenon could be a unique probe of living tissues. Realization of clinical and medical science applications beyond lung airspace imaging requires methods of efficient delivery of laser-polarized xenon to tissues, because of the short spin-lattice relaxation times and relatively low concentrations of xenon attainable in the body. Preliminary results from the application of a polarized xenon injection technique for in vivo 129Xe NMR/MRI are extrapolated along with a simple model of xenon transit to show that the peak local concentration of polarized xenon delivered to tissues by injection may exceed that delivered by respiration by severalfold.

By means of optical pumping with laser light it is possible to enhance the nuclear spin polarization of gaseous xenon by four to five orders of magnitude. The enhanced polarization has allowed advances in nuclear magnetic resonance (NMR) spectroscopy and magnetic resonance imaging (MRI), including polarization transfer to molecules and imaging of lungs and other void spaces. A critical issue for such applications is the delivery of xenon to the sample while maintaining the polarization. Described herein is an efficient method for the introduction of laser-polarized xenon into systems of biological and medical interest for the purpose of obtaining highly enhanced NMR/MRI signals. Using this method, we have made the first observation of the time-resolved process of xenon penetrating the red blood cells in fresh human blood - the xenon residence time constant in the red blood cells was measured to be 20.4 [+ or -] 2 ms. The potential of certain biologically compatible solvents for delivery of laser-polarized xenon to tissues for NMR/MRI is discussed in light of their respective relaxation and partitioning properties.

The events to do with peopling the New World archaeologically represented by 'Clovis' and 'Folsom' have been - tantalizingly - beyond the range of radiocarbon calibration. Now calibration extends further, [...]

Optical pumping with laser light can be used to polarize the nuclear spins of gaseous xenon-129. When hyperpolarized xenon-129 is dissolved in liquids, a time-dependent departure of the proton spin polarization from its thermal equilibrium is observed. The variation of the magnetization is an unexpected manifestation of the nuclear Overhauser effect, a consequence of cross-relaxation between the spins of solution protons and dissolved xenon-129. Time-resolved magnetic resonance images of both nuclei in solution show that the proton magnetization is selectively perturbed in regions containing spin-polarized xenon-129. This effect could find use in nuclear magnetic resonance spectroscopy of surfaces and proteins and in magnetic resonance imaging., Sensitivity poses a persistent challenge to nuclear magnetic resonance (NMR) spectroscopy and magnetic resonance imaging (MRI). One problem is low spin polarization, the very small population difference between 'up' and [...]

The Calaveras skull, first reported in 1866, represents the earliest purported fossil human discovery in California and one of the earliest in the New World. The specimen is in the possession of the Peabody Museum, Harvard University. The validity of the original "Tertiary" age assignment was rejected by the first generation of professional American archaeologists early in the twentieth century. Radiocarbon analyses using both conventional decay counting and accelerator mass spectrometry indicate a late Holocene age for the Calaveras skull.

Radiocarbon measurements have been obtained on contemporary plant samples collected at the site of Monte Verde, Chile, to examine the possibility that a local [C.sup.14] reservoir effect impinges on the […]