Strong microwave squeezing above 1 Tesla and 1 Kelvin.

Squeezed states of light have been used extensively to increase the precision of measurements, from the detection of gravitational waves to the search for dark matter. In the optical domain, high levels of vacuum noise squeezing are possible due to the availability of low loss optical components and high-performance squeezers. At microwave frequencies, however, limitations of the squeezing devices and the high insertion loss of microwave components make squeezing vacuum noise an exceptionally difficult task.

Latched detection of zeptojoule spin echoes with a kinetic inductance parametric oscillator.

When strongly pumped at twice their resonant frequency, nonlinear resonators develop a high-amplitude intracavity field, a phenomenon known as parametric self-oscillations. The boundary over which this instability occurs can be extremely sharp and thereby presents an opportunity for realizing a detector. Here, we operate such a device based on a superconducting microwave resonator whose nonlinearity is engineered from kinetic inductance.

In situ amplification of spin echoes within a kinetic inductance parametric amplifier.

The use of superconducting microresonators together with quantum-limited Josephson parametric amplifiers has enhanced the sensitivity of pulsed electron spin resonance (ESR) measurements by more than four orders of magnitude. So far, the microwave resonators and amplifiers have been designed as separate components due to the incompatibility of Josephson junction-based devices with magnetic fields. This has produced complex spectrometers and raised technical barriers toward adoption of the technique.

Initiating and Monitoring the Evolution of Single Electrons Within Atom-Defined Structures.

Using a noncontact atomic force microscope, we track and manipulate the position of single electrons confined to atomic structures engineered from silicon dangling bonds on the hydrogen terminated silicon surface. An attractive tip surface interaction mechanically manipulates the equilibrium position of a surface silicon atom, causing rehybridization that stabilizes a negative charge at the dangling bond. This is applied to controllably switch the charge state of individual dangling bonds.

All-electronic Nanosecond-resolved Scanning Tunneling Microscopy: Facilitating the Investigation of Single Dopant Charge Dynamics.

The miniaturization of semiconductor devices to scales where small numbers of dopants can control device properties requires the development of new techniques capable of characterizing their dynamics. Investigating single dopants requires sub-nanometer spatial resolution, which motivates the use of scanning tunneling microscopy (STM). However, conventional STM is limited to millisecond temporal resolution.

Visible-Light Actinometry and Intermittent Illumination as Convenient Tools to Study Ru(bpy)3Cl2 Mediated Photoredox Transformations.

Photoredox catalysis provides many green opportunities for radical-mediated synthetic transformations. However, the determination of the underlying mechanisms has been challenging due to lack of quantitative methods that can be easily implemented in synthetic labs, where this research tends to be centered. We report here on the development, characterization and calibration of a novel actinometer based on the photocatalyst tris(2,2'-bipyridyl)ruthenium(II) chloride (Ru(bpy)3Cl2).

Plasma amylin concentrations in fasted and fed rats quantified by a monoclonal immunoenzymometric assay.

Amylin is a 37-amino acid peptide co-secreted from the pancreatic beta-cell with insulin in response to nutrient stimuli. Plasma amylin concentrations in the rat are reported to vary widely. We have employed a recently-developed immunoenzymometric assay to quantify plasma amylin concentrations in fasted, fed and glucose-administered rats.

Effects of rat amylin on renal function in the rat.

Amylin is a peptide secreted from the pancreatic beta-cell along with insulin in response to nutrient stimuli. Amylin has been reported to delay gastric emptying, inhibit glucagon secretion and gastric acid secretion, increase plasma lactate, plasma glucose and plasma renin activity, and decrease plasma calcium. Receptors for amylin have been found in the rat nucleus accumbens and the kidney.

Nephrectomy decreases amylin and pramlintide clearance in rats.

Amylin is a 37 amino acid hormone, co-secreted with insulin from the pancreatic beta-cell in response to nutrient stimuli. Because the human amylin analog, pramlintide, is being tested in patients with diabetes mellitus, a known risk factor for nephropathy, we examined the role of the kidney on amylin and pramlintide metabolism and action in functionally nephrectomized rats. Nephrectomy markedly altered amylin metabolism: it increased incremental area under the plasma amylin concentration curve 3.

Comparison of the in vitro and in vivo pharmacology of adrenomedullin, calcitonin gene-related peptide and amylin in rats.

Adrenomedullin has been reported to be structurally similar to a group of peptides that includes amylin, calcitonin and calcitonin gene-related peptide (CGRP). Human and rat adrenomedullin displaced [125I]CGRP from membranes of SK-N-MC cells (CGRP receptors) with affinities intermediate between those of rat amylin and rat CGRP alpha (Ki values 0.12 +/- 0.

Lactate production from the rat hindlimb is increased after glucose administration and is suppressed by a selective amylin antagonist: evidence for action of endogenous amylin in skeletal muscle.

By serially measuring blood flow and venous-arterial lactate differences across the hindlimb of the fasted anesthetized rat, we examined (1) whether exogenous amylin increased muscle lactate production in vivo, (2) whether glucose administration increased muscle lactate production, and (3), by using the selective amylin antagonist AC187 to block endogenous peptide, whether amylin secreted in response to glucose could mediate muscle lactate production. Abdominal aortic flow was unchanged by any treatment. Hindlimb lactate production was increased by both 100 micrograms s.

Gastric emptying is accelerated in diabetic BB rats and is slowed by subcutaneous injections of amylin.

Gastric emptying was measured in normal and insulin-treated spontaneously diabetic BB rats using the retention of an acaloric methylcellulose gel containing phenol red delivered by gavage. Dye content in stomachs removed after killing 20 min later was determined spectroscopically, and was compared to that in rats killed immediately after gavage to assess emptying. Diabetic rats had a markedly greater gastric emptying (90.

Amylin regulation of carbohydrate metabolism.

This review describes how amylin may work in the control of carbohydrate metabolism by actions on gastric emptying and on muscle glycogen metabolism. Amylin, which is co-secreted with insulin from pancreatic beta-cells in response to nutrient stimuli, affects both carbohydrate absorption and carbohydrate disposal. Amylin appears to regulate carbohydrate metabolism as a partner to insulin.

Monoethylglycinexylide formation in assessing pediatric donor liver function.

Lidocaine metabolism to monoethylglycinexylide (MEGX) has been described as a novel method to assess liver function in adult transplant donors and recipients. While this assay appears to offer a number of advantages over existing liver function tests, limited work has been done to evaluate its potential in the pediatric population. This study evaluated MEGX formation in potential pediatric liver donors (n = 35) and a control group of children (n = 16).

Concentrations of phosphorylated zidovudine (ZDV) in patient leukocytes do not correlate with ZDV dose or plasma concentrations.

Zidovudine (ZDV) elicits its antiviral effect through intracellular metabolism to the 5'-triphosphate, which interferes with viral replication. Monitoring of the active metabolites of ZDV in cells could lead to an intracellular therapeutic range. This study was performed to determine whether a radioimmunoassay, previously used for in vitro quantitation of total phosphorylated ZDV inside peripheral blood leukocytes, could be used for similar determinations in patient samples.

Clinical diagnosis by nuclear magnetic resonance spectroscopy. If not now, when?

Nuclear magnetic resonance spectroscopy is the epitome of the high-technology, expensive diagnostic method. Extrapolation from a limited number of patient examinations and from experiments in animal models predicts a bright future for the method. However, several barriers block widespread clinical application in the near future; technical difficulties still exist but they seem to be resolvable in due course.

Injury and recovery of the liver from preservation assessed by 31P NMR spectroscopy: the contrast between preservation with Collins' solution and Ringer's lactate solution.

The biochemistry of hepatic injury and recovery from preservation for transplantation was studied in rat liver perfused in vitro with erythrocytes. ATP and its metabolites, inorganic phosphate (Pi) and pH were quantitated as often as every 2.5 min by 31P NMR spectroscopy during preservation and recovery.