Resonant Processes in a Frozen Gas

We present a theory of resonant processes in a frozen gas of atoms interacting via dipole-dipole potentials that vary as $r^{-3}$, where $r$ is the interatomic separation. We supply an exact result for a single atom in a given state interacting resonantly with a random gas of atoms in a different state. The time development of the transition process is calculated both on- and off-resonance, and the linewidth with respect to detuning is obtained as a function of time $t$. We introduce a random spin Hamiltonian to model a dense system of resonators and show how it reduces to the previous model in the limit of a sparse system. We derive approximate equations for the average effective spin, and we use them to model the behavior seen in the experiments of Anderson et al. and Lowell et al. The approach to equilibrium is found to be proportional to $\exp (-\sqrt{\gamma_{eq}t}$), where the constant $\gamma _{eq}$ is explicitly related to the system's parameters.Comment: 30 pages, 6 figure

‘Together … for only a moment’ British newspaper constructions of altruistic non-commercial surrogate motherhood

Objectives: To explore how national altruistic surrogacy is framed in a representative selection of the British press. Methods: A study of 90 British national newspaper articles was carried out using the Lexis-Nexis data base to search for articles on altruistic surrogacy. Content analysis of gain, loss, neutral frames and high or low alarm and vulnerability frames in the titles and the body of the text was carried out. The type of construction used in the article content was also analysed. Data were coded and consensus reached using a coding strategy specifically developed for the purposes of this study. Results: Titles and content were predominantly loss, high alarm and high vulnerability framed. The content was also gain framed, and written with a focus on the social and legal aspects differentially between the newspaper types. Discussion: The tabloid press emphasizes social issues, and the middle market and serious press focus on legal issues of altruistic surrogacy. Selectively framed and reinforced information provided by the different newspapers, reflect the different readership, with Tabloid readers likely to be, surrogates (mostly from lower socioeconomic strata) and serious/ middle-market readers likely to be commissioning parents (mostly professionals)

Measurement of the vector analyzing power in elastic electron-proton scattering as a probe of double photon exchange amplitudes

We report the first measurement of the vector analyzing power in inclusive transversely polarized elastic electron-proton scattering at Q^2 = 0.1 (GeV/c)^2 and large scattering angles. This quantity should vanish in the single virtual photon exchange, plane wave impulse approximation for this reaction, and can therefore provide information on double photon exchange amplitudes for electromagnetic interactions with hadronic systems. We find a non-zero value of A=-15.4+/-5.4 ppm. No calculations of this observable for nuclei other than spin 0 have been carried out in these kinematics, and the calculation using the spin orbit interaction from a charged point nucleus of spin 0 cannot describe these data.Comment: 4 pages, 2 figures, submitted to Phys. Rev. Let

Postcopulatory selection for dissimilar gametes maintains heterozygosity in the endangered North Atlantic right whale

Publisher's Version/PDFAlthough small populations are expected to lose genetic diversity through genetic drift and inbreeding, a number of mechanisms exist that could minimize this genetic decline. Examples include mate choice for unrelated mates and fertilization patterns biased toward genetically dissimilar gametes. Both processes have been widely documented, but the long-term implications have received little attention. Here, we combined over 25 years of field data with high-resolution genetic data to assess the long-term impacts of biased fertilization patterns in the endangered North Atlantic right whale. Offspring have higher levels of microsatellite heterozygosity than expected from this gene pool (effect size = 0.326, P < 0.011). This pattern is not due to precopulatory mate choice for genetically dissimilar mates (P < 0.600), but instead results from postcopulatory selection for gametes that are genetically dissimilar (effect size = 0.37, P < 0.003). The long-term implication is that heterozygosity has slowly increased in calves born throughout the study period, as opposed to the slight decline that was expected. Therefore, this mechanism represents a natural means through which small populations can mitigate the loss of genetic diversity over time

The Lantern Vol. 50, No. 1, Fall 1983

• Reaching for My Dream • All Hail • Appreciation • Egotism • Me (Dedicated to...) • Butterfly • Balloon and Bird • Never Again • Mother • The Deaf Ears • Healing • Distress • Silent Death • Whose Reality Is It Anyway? • To Helen • Luna Llena y Soledad • Saved • Jenny • Slope • A Poem in C Minor • A Birth of Proficiency • The Traveling Man • Competing With the Sea • To R. • The Child • And Besides • An Actress\u27 Demise • A Loving Tribute to Francis • Rapunzel • Memorieshttps://digitalcommons.ursinus.edu/lantern/1123/thumbnail.jp

Validation of Serum Neurofilament Light Chain as a Biomarker of Parkinson's Disease Progression

Background: The objective of this study was to assess neurofilament light chain as a Parkinson’s disease biomarker. Methods: We quantified neurofilament light chain in 2 independent cohorts: (1) longitudinal cerebrospinal fluid samples from the longitudinal de novo Parkinson’s disease cohort and (2) a large longitudinal cohort with serum samples from Parkinson’s disease, other cognate/neurodegenerative disorders, healthy controls, prodromal conditions, and mutation carriers. Results: In the Parkinson’s Progression Marker Initiative cohort, mean baseline serum neurofilament light chain was higher in Parkinson’s disease patients (13 � 7.2 pg/mL) than in controls (12 � 6.7 pg/mL), P = 0.0336. Serum neurofilament light chain increased longitudinally in Parkinson’s disease patients versus controls (P < 0.01). Motor scores were positively associated with neurofilament light chain, whereas some cognitive scores showed a negative association. Conclusions: Neurofilament light chain in serum samples is increased in Parkinson’s disease patients versus healthy controls, increases over time and with age, and correlates with clinical measures of Parkinson’s disease severity. Although the specificity of neurofilament light chain for Parkinson’s disease is low, it is the first blood-based biomarker candidate that could support disease stratification of Parkinson’s disease versus other cognate/neurodegenerative disorders, track clinical progression, and possibly assess responsiveness to neuroprotective treatments. However, use of neurofilament light chain as a biomarker of response to neuroprotective interventions remains to be assessed

Measurement of the vector analyzing power in elastic electron-proton scattering as a probe of the double virtual Compton amplitude

We report the first measurement of the vector analyzing power in inclusive transversely polarized elastic electron-proton scattering at Q^2=0.1(GeV/c)^2 and large scattering angles. This quantity must vanish in the single virtual photon exchange, plane-wave impulse approximation for this reaction, and can therefore provide information on two photon exchange amplitudes for electromagnetic interactions with hadronic systems. The observable we have measured is driven by the imaginary part of the two photon exchange amplitude, the hadronic side of which is simply the Compton amplitude for the proton with two virtual photons. We find a small but nonzero value of A=-15.4±5.4 ppm

Why Does Exercise “Triggerâ€? Adaptive Protective Responses in the Heart?

Numerous epidemiological studies suggest that individuals who exercise have decreased cardiac morbidity and mortality. Pre-clinical studies in animal models also find clear cardioprotective phenotypes in animals that exercise, specifically characterized by lower myocardial infarction and arrhythmia. Despite the clear benefits, the underlying cellular and molecular mechanisms that are responsible for exercise preconditioning are not fully understood. In particular, the adaptive signaling events that occur during exercise to “trigger� cardioprotection represent emerging paradigms. In this review, we discuss recent studies that have identified several different factors that appear to initiate exercise preconditioning. We summarize the evidence for and against specific cellular factors in triggering exercise adaptations and identify areas for future study

The Lantern Vol. 50, No. 2, Spring 1984

• The Storm • Je ne sais pas • The Ghetious Blastious • An Empty Cradle • The Playing Hands • Battle Hymn • A Limerick • Parting Thoughts • The River • Miss You • De la Tristeza • Two So Special • Time of the Unicorn • The Absence • Thru The Breeze • Is the World Really a Round Ball? • Brother • To Michael • Gravity • Refuge • Der Witwer • Plastic Flowers Never Die • Book on the Shelfhttps://digitalcommons.ursinus.edu/lantern/1124/thumbnail.jp

The Parkinson's progression markers initiative (PPMI) - establishing a PD biomarker cohort

Objective The Parkinson's Progression Markers Initiative (PPMI) is an observational, international study designed to establish biomarker-defined cohorts and identify clinical, imaging, genetic, and biospecimen Parkinson's disease (PD) progression markers to accelerate disease-modifying therapeutic trials. Methods A total of 423 untreated PD, 196 Healthy Control (HC) and 64 SWEDD (scans without evidence of dopaminergic deficit) subjects were enrolled at 24 sites. To enroll PD subjects as early as possible following diagnosis, subjects were eligible with only asymmetric bradykinesia or tremor plus a dopamine transporter (DAT) binding deficit on SPECT imaging. Acquisition of data was standardized as detailed at www.ppmi-info.org. Results Approximately 9% of enrolled subjects had a single PD sign at baseline. DAT imaging excluded 16% of potential PD subjects with SWEDD. The total MDS-UPDRS for PD was 32.4 compared to 4.6 for HC and 28.2 for SWEDD. On average, PD subjects demonstrated 45% and 68% reduction in mean striatal and contralateral putamen Specific Binding Ratios (SBR), respectively. Cerebrospinal fluid (CSF) was acquired from >97% of all subjects. CSF (PD/HC/SWEDD pg/mL) α-synuclein (1845/2204/2141) was reduced in PD vs HC or SWEDD (P < 0.03). Similarly, t-tau (45/53) and p-tau (16/18) were reduced in PD versus HC (P < 0.01), Interpretation PPMI has detailed the biomarker signature for an early PD cohort defined by clinical features and imaging biomarkers. This strategy provides the framework to establish biomarker cohorts and to define longitudinal progression biomarkers to support future PD treatment trials