Perfect countably infinite Steiner triple systems

We use a free construction to prove the existence of perfect Steiner triple systems on a countably infinite point set. We use a specific countably infinite family of partial Steiner triple systems to start the construction, thus yielding 2ℵ0 non-isomorphic perfect systems

Matter-wave grating distinguishing conservative and dissipative interactions

We propose an optical grating for matter waves that separates molecules depending on whether their interaction with the light is conservative or dissipative. Potential applications include fundamental tests of quantum mechanics, measurement of molecular properties and the ability to selectively prepare matter waves with different internal temperatures

Eagle Syndrome: A Rare Case of Atraumatic, Painful Cervical Neck Swelling

Introduction: Painful neck swelling is a common emergency complaint but can present diagnostic challenges. Eagle syndrome is a rare clinical entity in which a pathologically elongated styloid process or ossified stylohyoid ligament produces a constellation of symptoms in the head and neck region.Case Report: We present the case of a 50-year-old male with a spontaneous, atraumatic fracture of an elongated styloid process associated with hematoma formation and radiological findings of airway impingement.Discussion: The classic triad for Eagle syndrome consists of unilateral cervicofacial pain, globus sensation, and dysphagia. Diagnosis of Eagle syndrome should be made based on a combination of physical examination and radiological findings. Treatment options vary based on severity of symptoms.Conclusion: Although more likely to be an indolent and progressive complaint, providers in the acute care setting should be familiar with Eagle syndrome due to the potential for a spontaneous fracture of an elongated styloid process to cause acute, painful neck swelling and life-threatening airway compromise

Chirality and the angular momentum of light

Chirality is exhibited by objects that cannot be rotated into their mirror images. It is far from obvious that this has anything to do with the angular momentum of light, which owes its existence to rotational symmetries. There is nevertheless a subtle connection between chirality and the angular momentum of light. We demonstrate this connection and, in particular, its significance in the context of chiral light–matter interactions

Human to Mosquito Transmission of Dengue Viruses

The successful transmission of dengue virus from a human host to a mosquito vector requires a complex set of factors to align. It is becoming increasingly important to improve our understanding of the parameters that shape the human to mosquito component of the transmission cycle so that vaccines and therapeutic antivirals can be fully evaluated and epidemiological models refined. Here we describe these factors, and discuss the biological and environmental impacts and demographic changes that are influencing these dynamics. Specifically, we examine features of the human infection required for the mosquito to acquire the virus via natural blood feeding, as well as the biological and environmental factors that influence a mosquito's susceptibility to infection, up to the point that they are capable of transmitting the virus to a new host

Computer Simulation of Cytoskeleton-Induced Blebbing in Lipid Membranes

Blebs are balloon-shaped membrane protrusions that form during many physiological processes. Using computer simulation of a particle-based model for self-assembled lipid bilayers coupled to an elastic meshwork, we investigated the phase behavior and kinetics of blebbing. We found that blebs form for large values of the ratio between the areas of the bilayer and the cytoskeleton. We also found that blebbing can be induced when the cytoskeleton is subject to a localized ablation or a uniform compression. The results obtained are qualitatively in agreement with the experimental evidence and the model opens up the possibility to study the kinetics of bleb formation in detail.Comment: To appear in Physical Review

Bladder outlet obstruction in painful bladder syndrome/interstitial cystitis

Aims Obstructive symptoms such as slow stream, dribbling and straining are often reported by painful bladder syndrome and interstitial cystitis (PBS/IC) patients. Our hypothesis was that some patients with PBS/IC have an associated measurable bladder outlet obstruction (BOO) secondary to dysfunctional voiding and that those patients with more severe PBS/IC are more likely to have BOO. Methods This is a retrospective chart review of female patients diagnosed with PBS/IC based on the NIDDK research definition. Charts were reviewed for clinical symptom severity, ulcer or non-ulcer PBS/IC on cystoscopy, and pressure-flow urodynamics (UDPF). Patients were excluded if they had a urinary infection at the time of urodynamics or did not meet study entry requirements. The cut-off values of ≤12 ml/sec and ≥25 cm of water was used to define BOO. Results Of the 231 women: 38 had ulcer PBS/IC and 193 had non-ulcer PBS/IC. MCC was 269 ml in non-ulcer PBS/IC and 200 ml in ulcer PBS/IC ( P  = 0.006). One hundred eleven women (48%) met criteria for obstruction. MCC was 298 ml in the non-obstructed group and 214 ml in the obstructed group ( P  < 0.0001). The maximum flow with non-ulcer PBS/IC was 11.0 ml/sec and in ulcer PBS/IC 8.9 ml/sec ( P  = 0.04) Detrusor pressure at maximum flow was 33.3 cm H 2 O, in non-ulcer, and 37.4 cm H 2 O in ulcer PBS/IC ( P  = 0.01). Conclusions Forty-eight percent of our PBS/IC patients have BOO, and increasing severity of PBS/IC is associated with higher voiding pressure. Neurourol. Urodynam. 28:944–948, 2009. © 2009 Wiley-Liss, Inc.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/64338/1/20729_ftp.pd

Twenty Years of Timing SS433

We present observations of the optical ``moving lines'' in spectra of the Galactic relativistic jet source SS433 spread over a twenty year baseline from 1979 to 1999. The red/blue-shifts of the lines reveal the apparent precession of the jet axis in SS433, and we present a new determination of the precession parameters based on these data. We investigate the amplitude and nature of time- and phase-dependent deviations from the kinematic model for the jet precession, including an upper limit on any precessional period derivative of $\dot P < 5 \times 10^{-5}$. We also dicuss the implications of these results for the origins of the relativistic jets in SS433.Comment: 21 pages, including 9 figures. To appear in the Astrophysical Journa