Superfluid helium quantum interference devices: physics and applications.

We present an overview of recent developments related to superfluid helium quantum interference devices (SHeQUIDs). We discuss the physics of two reservoirs of superfluid helium coupled together and describe the quantum oscillations that result from varying the coupling strength. We explain the principles behind SHeQUIDs that can be built based on these oscillations and review some techniques and applications.

Intracameral phenylephrine to prevent floppy iris syndrome during cataract surgery in patients on tamsulosin.

PURPOSE: To describe the use of intracameral phenylephrine to prevent the floppy iris syndrome seen in patients who are on the drug tamsulosin for benign prostatic hypertrophy, during cataract surgery. SETTING: Prince Charles Eye Unit, King Edward VII Hospital, Windsor, Berkshire, UK. METHOD: Seven patients who were on systemic tamsulosin for benign prostatic hypertrophy received intracameral phenylephrine before capsulorexhis during their cataract surgery. RESULTS: There was a significant reduction in the amount of mobility of the iris, reduction in the expected fluttering, and sustained papillary dilatation. ConclusionIntracameral phenylephrine is a simple and effective tool to prevent the effects of floppy iris syndrome in those patients undergoing cataract surgery who are on systemic tamsulosin.

Preoperative assessment of secondary intraocular lens implantation for aphakia: a comparison of 2 techniques.

PURPOSE: To compare the preoperative evaluation of secondary intraocular lens (IOL) implantation in aphakic adults following cataract extraction in childhood using slitlamp examination and high-frequency ultrasound (HFU). METHODS: In a prospective case series, patients who had had lensectomies for congenital cataracts without primary implantation IOL were evaluated for secondary IOL insertion. Slitlamp examination and HFU were performed to study the degree of ciliary sulcus support and iridocapsular adhesions. The choice of IOL (posterior sulcus supported or anterior chamber) was compared using the 2 techniques. RESULTS: Nine eyes of 5 patients (3 men and 2 women aged 15 to 40 years) were assessed for secondary IOL insertion. Clinical slitlamp examination suggested that 3 of 9 eyes had inadequate sulcociliary support, but HFU of these eyes revealed more than adequate capsular remnants. In all 9 eyes, sulcus-supported posterior chamber IOLs were implanted. No postoperative complications were observed, and no patients required surgery for dislocated IOL. CONCLUSIONS: High-frequency ultrasound is a useful adjunct for the preoperative assessment of secondary ciliary sulcus-supported IOL implantation in aphakic patients who had congenital cataract extraction without IOL implantation. In patients in whom inadequate dilation precludes the detection of capsular support, posterior ciliary sulcus-supported secondary IOL implantation should be considered preoperatively. Although the technique enhances surgical planning and informed patient consent, the final decision occurs at the time of surgery with direct visualization of the ciliary sulcus support.

Thermally driven josephson oscillations in superfluid 4He.

We find that a temperature differential can drive superfluid oscillations in 4He. The oscillations are excited by a heater which causes a time dependent temperature differential across an array of 70 nm apertures. By measuring the oscillation frequency and simultaneously determining both temperature and pressure differentials we prove the validity of the most general form of the Josephson frequency relation. These observations were made near saturated vapor pressure, within a few mK of the superfluid transition temperature.

Oscillatory motion: quantum whistling in superfluid helium-4.

Fundamental considerations predict that macroscopic quantum systems such as superfluids and the electrons in superconductors will undergo oscillatory motion when forced through a small constriction. Here we induce these oscillations in superfluid helium-4 (4He) by pushing it through an array of nanometre-sized apertures. The oscillations, which are detected as an audible whistling sound, obey the so-called Josephson frequency relation and occur coherently among all the apertures. The discovery of this property in 4He at the relatively high temperature of 2 K (2,000 times higher than the temperature at which a related but different phenomenon occurs in 3He) may pave the way for a new class of practical rotation sensors of unprecedented precision.

Vortex formation and annihilation in three textures of rotating superfluid 3He-A.

Textures, textural transformation, and formation and annihilation of a single vortex were investigated in narrow cylinders with 100 microm radius in A-phase under rotation up to 6.28 rad/sec. Three textures were found, depending on the cooling conditions of the sample through the superfluid transition temperature T(c). We found the gyromagnetic effect of textures; that is, two textures (A or B) could be selected either by applying a magnetic field in parallel or anti-parallel to the rotation axis. The critical angular speed of a single vortex formation Omega(f) and that of annihilation Omega(a) for each texture were measured. The textural transformation in type A texture was induced by rotation. Both type A and B textures held macroscopic angular momentum along the rotation axis. We identified the texture for type A, B, and C as Mermin-Ho, radial disgyration, and a soliton type of defect along the axis, respectively.

Measuring the economic costs of antimicrobial resistance in hospital settings: summary of the Centers for Disease Control and Prevention-Emory Workshop.

Health systems administrators and clinicians need refined calculations of the attributable cost of infections due to drug-resistant microorganisms to develop and assess cost-effective prevention strategies that deal with these infections. To date, however, efforts to provide this information have yielded widely variable and often conflicting estimates. This lack of reproducibility is largely attributable to problems in study design and in the methods used to identify and measure costs. Addressing these methodological issues was the focus of a workshop that included participants from a broad range of backgrounds, including economics, epidemiology, health care management, health care outcomes research, and clinical care. This workshop summary presents the advantages and disadvantages of various research designs as well as particular methodological issues related to the measurement of the economic cost of resistance in health care settings. Suggestions are made for needed common definitions and approaches, study areas for future research are considered, and priority investigations are identified.

Quantum interference of superfluid 3He.

Celebrated interference experiments have demonstrated the wave nature of light and electrons, quantum interference being the manifestation of wave-particle duality. More recently, double-path interference experiments have also demonstrated the quantum-wave nature of beams of neutrons, atoms and Bose-Einstein condensates. In condensed matter systems, double-path quantum interference is observed in the d.c. superconducting quantum interference device (d.c. SQUID). Here we report a double-path quantum interference experiment involving a liquid: superfluid 3He. Using a geometry analogous to the superconducting d.c. SQUID, we control a quantum phase shift by using the rotation of the Earth, and find the classic interference pattern with periodicity determined by the 3He quantum of circulation.

Observation of the superfluid shapiro effect in a 3He weak link.

We have studied the mass currents through a superfluid 3He Josephson weak link in the presence of an externally applied ac pressure modulation. Characteristic changes in the dc mass currents are observed whenever the superfluid Josephson frequency omega(J) is an integer multiple of the ac modulation frequency omega. The measured dependencies of these current changes on ac pressure amplitude are in excellent agreement with theory describing quantum phase dynamics of superfluid 3He weak links. These results establish the superfluid analog of the superconducting Shapiro effect.

Delirium.

BACKGROUND: Delirium is a serious and often undetected neuropsychiatric syndrome. Failure to recognize and manage delirium can lead to longer hospital stays and increased morbidity and mortality, especially among the elderly. REVIEW SUMMARY: This article reviews definitions and diagnosis. The Diagnostic and Statistical Manual of Mental Disorders, 4th edition, and the International Statistical Classification of Diseases and Related Health Problems, 10th edition, criteria are quite similar in their diagnostic criteria. Risk factors include advanced age, preexisting brain disease or cognitive impairment, multiple medications, and severe medical problems. Delirium in the elderly can be more subtle and recovery more prolonged. Diagnosis is more complex if there is already an underlying dementia. An organized approach should be used to discover etiology and in ordering appropriate laboratory studies. At the cellular level, delirium is considered to be a reversible disregulation of neuronal membrane function. This involves a selective vulnerability of certain populations of neurons and neurotransmitter dysfunction. Practical treatment issues are reviewed. CONCLUSIONS: Despite advances, delirium is usually still diagnosed at the bedside. Having an organized approach to diagnosis and understanding the underlying pathophysiology should help with overall evaluation and treatment.

Treatment of chronic daily posttraumatic headache with divalproex sodium.

OBJECTIVE: To determine the effectiveness of divalproex sodium in the treatment of chronic daily posttraumatic headaches. BACKGROUND: Divalproex sodium has been found to be useful for the treatment of migraine and chronic daily headache. No studies have been done to evaluate effectiveness in posttraumatic headache. METHODS: A retrospective review was done of 100 patients treated with divalproex for chronic daily posttraumatic headache of 2 months or longer. RESULTS: Sixty percent of patients with chronic posttraumatic headache had mild to moderate improvement in their headaches after at least 1 month of divalproex sodium. Forty percent either showed no response (26%) or discontinued treatment because of side effects (14%). Fifty-eight percent of patients showing improvement had a change in headache pattern from daily to episodic. CONCLUSIONS: Divalproex sodium appears to be safe and effective for treatment of patients with persistent, chronic daily posttraumatic headaches.

New flow dissipation mechanisms in superfluid 3He.

We have studied the flow of superfluid 3He-B forced through small apertures. There are unexpectedly large dissipative currents, which can be described by two independent processes. One process involves the creation of quasiparticles within the aperture and their subsequent acceleration in the ambient pressure gradient. The second process involves the dissipative precession of a texture in a geometry-induced anisotropic order parameter. For both mechanisms we make a simple estimate of the relevant effect and find these agree well with the data.

A commitment to community.

Retiring Republican Member of Congress for the 48th District of California, Dr. Ron Packard reflects on the qualities of success that are common in dentistry and politics and stresses the importance of community.

Epidemiology and pathogenesis of posttraumatic headache.

This article presents an overview of the epidemiology and pathophysiology of posttraumatic headache. It reviews definitions of mild head injury (MHI), mild traumatic brain injury (MTBI), and concussion, and discusses the confusion that often occurs with these terms. Headache types and their pathophysiology are examined in detail. Just as the exact pathophysiology is unknown for migraine and other types of headache, the exact pathophysiology of headache after trauma is also still unknown in many cases. Possible connections between head or neck injuries and headache are reviewed, as well as hypothesized neurochemical changes that may occur in both migraine and traumatic brain injury (TBI). Psychological and legal factors are also considered.

'No other logical choice': global malaria eradication and the politics of international health in the post-war era.

In 1955 the Eighth World Health Assembly voted to initiate a program for the global eradication of malaria. The global eradication of malaria represented a remarkable leap of faith. Many health authorities, both within and outside the Assembly, viewed eradication as at best fool hardy, and at worst, potentially disastrous. To understand why the World Health Assembly went ahead with a Global Eradication strategy, despite these concerns, it is necessary to examine the politics of international health and development in the post-war era. This political context shaped decisions about the adoption of DDT as a primary tool in the fight against malaria, as well as the adoption of the Malaria Eradication Program. It is equally important to understand how the advocates of an eradication strategy shaped arguments and developed support for their cause in the years leading up to the Eighth World Health Assembly meeting.