A Hybrid Quantum Search Engine: A Fast Quantum Algorithm for Multiple Matches

In this paper we will present a quantum algorithm which works very efficiently in case of multiple matches within the search space and in the case of few matches, the algorithm performs classically. This allows us to propose a hybrid quantum search engine that integrates Grover's algorithm and the proposed algorithm here to have general performance better that any pure classical or quantum search algorithm.Comment: 26 pages, 8 Figure

Quantum Search Algorithm with more Reliable Behaviour using Partial Diffusion

In this paper, we will use a quantum operator which performs the inversion about the mean operation only on a subspace of the system ({\it Partial Diffusion Operator}) to propose a quantum search algorithm runs in O(\sqrt N/M}) for searching unstructured list of size $N$ with $M$ matches such that, $1\le M \le N$. We will show that the performance of the algorithm is more reliable than known quantum search algorithms especially for multiple matches within the search space. A performance comparison with Grover's algorithm will be provided.Comment: 27 pages, 9 figure

Biochemical studies on starch - type polysaccharides

In this thesis, chemical and enzymic studies on a number of starch-type polysaccharides are described, with special reference to the possible presence of anomolous linkages or other structural modifications

Myalgic Encephalomyelitis/Chronic Fatigue Syndrome Diagnosis and Management in Young People: A Primer

Myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS) is a complex disease that affects children and adolescents as well as adults. The etiology has not been established. While many pediatricians and other health-care providers are aware of ME/CFS, they often lack essential knowledge that is necessary for diagnosis and treatment. Many young patients experience symptoms for years before receiving a diagnosis. This primer, written by the International Writing Group for Pediatric ME/CFS, provides information necessary to understand, diagnose, and manage the symptoms of ME/CFS in children and adolescents. ME/CFS is characterized by overwhelming fatigue with a substantial loss of physical and mental stamina. Cardinal features are malaise and a worsening of symptoms following minimal physical or mental exertion. These post-exertional symptoms can persist for hours, days, or weeks and are not relieved by rest or sleep. Other symptoms include cognitive problems, unrefreshing or disturbed sleep, generalized or localized pain, lightheadedness, and additional symptoms in multiple organ systems. While some young patients can attend school, on a full or part-time basis, many others are wheelchair dependent, housebound, or bedbound. Prevalence estimates for pediatric ME/CFS vary from 0.1 to 0.5%. Because there is no diagnostic test for ME/CFS, diagnosis is purely clinical, based on the history and the exclusion of other fatiguing illnesses by physical examination and medical testing. Co-existing medical conditions including orthostatic intolerance (OI) are common. Successful management is based on determining the optimum balance of rest and activity to help prevent post-exertional symptom worsening. Medications are helpful to treat pain, insomnia, OI and other symptoms. The published literature on ME/CFS and specifically that describing the diagnosis and management of pediatric ME/CFS is very limited. Where published studies are lacking, recommendations are based on the clinical observations and practices of the authors

Fowler-Nordheim-like local injection of photoelectrons from a silicon tip

Tunneling between a photo-excited p-type silicon tip and a gold surface is studied as a function of tip bias, tip/sample distance and light intensity. In order to extend the range of application of future spin injection experiments, the measurements are carried out under nitrogen gas at room temperature. It is found that while tunneling of valence band electrons is described by a standard process between the semiconductor valence band and the metal, the tunneling of photoelectrons obeys a Fowler-Nordheim-like process directly from the conduction band. In the latter case, the bias dependence of the photocurrent as a function of distance is in agreement with theoretical predictions which include image charge effects. Quantitative analysis of the bias dependence of the dark and photocurrent spectra gives reasonable values for the distance, and for the tip and metal work functions. For small distances image charge effects induce a vanishing of the barrier and the bias dependence of the photocurrent is exponential. In common with many works on field emission, fluctuations in the tunneling currents are observed. These are mainly attributed to changes in the prefactor for the tunneling photocurrent, which we suggest is caused by an electric-field-induced modification of the thickness of the natural oxide layer covering the tip apex.Comment: 12 pages, 11 figures. Submitted to Phys. Rev.

Holocene stable isotope record of insolation and rapid climate change in a stalagmite from the Zagros of Iran

We explore Holocene climatic changes recorded by geochemical proxies in a single, well-dated, stalagmite from the northern Zagros Mountains of Iran, a region where stalagmite records have so far only provided short glimpses of Holocene climatic changes. Stalagmite KT-3 from Katalekhor Cave began growing ~9.5 ka under wet early Holocene conditions coincident with the timing of Sapropel 1. At this time d18O values were at or below 9.0‰, stalagmite growth diameter was at its maximum, 234U/238U0 activity values were low and trace element contents indicate flushing of the epikarst. Progressive reduction in winter precipitation amount after 7.0 ka, is recorded by increasing d18O and 234U/238U0 activity values and reduction in trace element contents and growth diameter until ~2.0 ka. These trends follow the reduction in summer insolation and agree with model-simulated changes in total rainfall and rainwater isotopes. Sub-centennial-scale variability is not a feature of the d18O or trace element records; this suggests a stable winter recharge regime, a feature that might militate against KT-3 d18O recording changes in the seasonality of rainfall. KT-3 d13C compositions are enriched relative to lower altitude stalagmites in the Levant, implying low soil CO2 contribution (thin montane soils). However, a broadly decreasing millennial-scale trend in d13C suggests that soil carbon contributions increased with time despite the progressive reduction in winter precipitation amount. The d13C changes probably reflect decreasing summer temperatures and less extreme wintertime coldness, driven by reducing summer and increasing winter-insolation respectively. These combined effects decreased effective evaporation and improved soil-moisture availability favouring vegetation development during the growth season. The d13C values also show ~1.5‰ centennial-scale variability with higher d13C values between 9.0 and 8.7 ka, 8.3 - 7.7 ka, 6.5 - 5.5 ka, 5.4 - 4.5 ka and ~4.3- 2.0 ka: three of these correspond with Rapid Climate Change (RCC) events based on non-seasalt potassium (Kþ) in Greenland ice cores. Higher d13C values indicate poor soil development caused by aridity. The centennial-scale d13C anomaly (8.3-7.7 ka) is in part overprinted by the ~160 year-long, 8.2 ka cold/dry event, but culmination ~7.7 ka corresponds with other records suggesting an intensified Siberian High Pressure system affecting regional climate. The centennial-scale d13C anomaly between 4.3 and 2.0 ka overlaps the 2.65 to 2.50 ka ‘Assyrian megadrought’ evident in stalagmite stable isotope records in northern Iraq. The KT-3 record is key in better understanding Holocene climate change in the central Zagros region, representative of montane ‘fertile crescent’ environments

A novel causal mechanism for grey squirrel bark stripping: The Calcium Hypothesis

AbstractGrey squirrels, Sciurus carolinensis, damage trees in the UK by stripping bark and eating the underlying phloem; squirrel motivation for damage is, however, unknown. Damage can result in deterioration of timber quality and a significant economic toll on the forestry industry. Prediction of severe damage followed by targeted killing of squirrels is the current recommended management option. However, the use of warfarin (an anticoagulant poison) is now restricted in the UK and other more humane methods of killing are labour-intensive, so an alternative solution is needed. A better understanding of what motivates grey squirrels to strip bark may enable a preventive approach to be developed. Whilst the bark stripping literature has explored predictive factors affecting the likelihood of damage, causal understanding is lacking. The aim of this review is to introduce the Calcium Hypothesis as a possible explanation for bark stripping, with a view to informing the prevention of damage. The Calcium Hypothesis states that grey squirrels damage trees to ameliorate a calcium deficiency. The main predictive factors of bark stripping behaviour each inform and lend support to the Calcium Hypothesis. Calcium is stored in tree phloem, and damage increases with phloem width, providing squirrels with more calcium per unit area ingested. Calcium levels increase in trees as active growth resumes after winter dormancy, this occurs immediately prior to the main bark stripping season of May–July, and trees growing most vigorously are at increased risk of damage. It is likely grey squirrels also have a requirement for calcium during the bark stripping season. Adult females will be under post-parturition pressures such as lactation, and juveniles will be going through their main period of bone growth, both of which likely represent a requirement for calcium – which supports an observed positive correlation between juvenile abundance and bark stripping. A high autumnal seed crop increases juvenile recruitment the following spring, and could also induce a requirement for calcium to a population due to the high phosphorus to calcium ratio of seeds. To further investigate the hypothesis, the extent to which grey squirrels can utilise calcium oxalate, as calcium occurs in bark, should be determined, and also the extent to which grey squirrels undergo seasonal periods of calcium deficiency. Increasing our causal understanding of bark stripping could inform the future development of preventive measures to aid forest management

Updated Planetary Mass Constraints of the Young V1298 Tau System Using MAROON-X

The early K-type T-Tauri star, V1298 Tau ($V=10\,{\rm mag}$, ${\rm age}\approx20-30\,{\rm Myr}$) hosts four transiting planets with radii ranging from $4.9-9.6\,R_\oplus$. The three inner planets have orbital periods of $\approx8-24\,{\rm d}$ while the outer planet's period is poorly constrained by single transits observed with \emph{K2} and \emph{TESS}. Planets b, c, and d are proto-sub-Neptunes that may be undergoing significant mass loss. Depending on the stellar activity and planet masses, they are expected to evolve into super-Earths/sub-Neptunes that bound the radius valley. Here we present results of a joint transit and radial velocity (RV) modelling analysis, which includes recently obtained \emph{TESS} photometry and MAROON-X RV measurements. Assuming circular orbits, we obtain a low-significance ($\approx2\sigma$) RV detection of planet c implying a mass of $19.8_{-8.9}^{+9.3}\,M_\oplus$ and a conservative $2\sigma$ upper limit of $<39\,M_\oplus$. For planets b and d, we derive $2\sigma$ upper limits of $M_{\rm b}<159\,M_\oplus$ and $M_{\rm d}<41\,M_\oplus$. For planet e, plausible discrete periods of $P_{\rm e}>55.4\,{\rm d}$ are ruled out at a $3\sigma$ level while seven solutions with $43.3<P_{\rm e}/{\rm d}<55.4$ are consistent with the most probable $46.768131\pm000076\,{\rm d}$ solution within $3\sigma$. Adopting the most probable solution yields a $2.6\sigma$ RV detection with mass a of $0.66\pm0.26\,M_{\rm Jup}$. Comparing the updated mass and radius constraints with planetary evolution and interior structure models shows that planets b, d, and e are consistent with predictions for young gas-rich planets and that planet c is consistent with having a water-rich core with a substantial ($\sim5\%$ by mass) H$_2$ envelope.Comment: 18 pages, 13 figures, accepted for publication in A