Loschmidt echo and fidelity decay near an exceptional point

Non-Hermitian classical and open quantum systems near an exceptional point (EP) are known to undergo strong deviations in their dynamical behavior under small perturbations or slow cycling of parameters as compared to Hermitian systems. Such a strong sensitivity is at the heart of many interesting phenomena and applications, such as the asymmetric breakdown of the adiabatic theorem, enhanced sensing, non-Hermitian dynamical quantum phase transitions and photonic catastrophe. Like for Hermitian systems, the sensitivity to perturbations on the dynamical evolution can be captured by Loschmidt echo and fidelity after imperfect time reversal or quench dynamics. Here we disclose a rather counterintuitive phenomenon in certain non-Hermitian systems near an EP, namely the deceleration (rather than acceleration) of the fidelity decay and improved Loschmidt echo as compared to their Hermitian counterparts, despite large (non-perturbative) deformation of the energy spectrum introduced by the perturbations. This behavior is illustrated by considering the fidelity decay and Loschmidt echo for the single-particle hopping dynamics on a tight-binding lattice under an imaginary gauge field.Comment: 11 pages, 6 figures, to appear in Annalen der Physi

The Mesolithic-Neolithic transition in western Scotland and its European context

The transition is considered in terms of four related questions: (i) HOW did the shift from foraging to farming happen? (ii) WHY did it happen? (iii) WHEN did it happen? (iv) WHY did it happen WHEN it did? The adoption of farming coincided with a shift to a more continental-type climate with lower winter precipitation, which improved the prospects for cereal cultivation. It is sug- gested that this was a key factor in the transition from Mesolithic to Neolithic across north-west Eu- rope as a whole.Mezolitsko-neolitski prehod obravnavamo glede na štiri povezana vprašanja: (i) KAKO se je zgodil prehod iz lovstva-nabiralništva v kmetovanje? (ii) ZAKAJ se je zgodil? (iii) KDAJ se je zgodil? (iv) ZAKAJ se je zgodil, KO se je zgodil? Do prevzema kmetovanja je prišlo v času, ko so klimatske razmere postale bolj kontinentalne in zimske padavine manj obilne. To je izboljšalo pogoje za gojenje žit. Menimo, da je bil to ključni dejavnik za prehod iz mezolitika v neolitik v celotni severozahodni Evropi

What Do Management Earnings Forecasts Convey About the Macroeconomy?

We decompose quantitative management earnings forecasts into macroeconomic and firm-specific components to determine the extent to which voluntary disclosure provided by management has macroeconomic information content. We provide evidence that the forecasts of bellwether firms, which are defined as firms in which macroeconomic news explains the greatest amount of variation in the forecasts, provide timely information to the market about the macroeconomy when bundled with earnings announcements. Further, we show that bellwether firms provide timely information about both industry-specific events and broader economic events. Finally, we document that the macroeconomic news in individual forecasts is more pronounced for bad news and point forecasts

Developing Policy For HIV/AIDS in Sport: Separating Fact From Fiction

In recent years, HIV-positive athletes have increasingly made the headlines, leading to questions and concerns regarding HIV transmission through sport. Based on limited understanding and irrational fear, athletes have been excluded from sport competitions or encouraged to retire prematurely. In other cases, they have been subjected to random, mandatory HIV testing prior to sport competition. Because HIV/AIDS is a medical and social problem, information from health-related sources is included in this analysis, including the modes of HIV transmission. This analysis focuses on further issues related to rights, obligations, risks, privacy, and policy. The growing dilemma for the sport professionals to weigh an athlete\u27s right to privacy against their own duty to warn in the decision-making process is examined, with a discussion on mandatory HIV testing for athletes. Guidelines based on principles of medical ethics are offered to aid sport practitioners in providing all athletes with the best possible service

Duality and the vibrational modes of a Cooper-pair Wigner crystal

When quantum fluctuations in the phase of the superconducting order parameter destroy the off-diagonal long range order, duality arguments predict the formation of a Cooper pair crystal. This effect is thought to be responsible for the static checkerboard patterns observed recently in various underdoped cuprate superconductors by means of scanning tunneling spectroscopy. Breaking of the translational symmetry in such a Cooper pair Wigner crystal may, under certain conditions, lead to the emergence of low lying transverse vibrational modes which could then contribute to thermodynamic and transport properties at low temperatures. We investigate these vibrational modes using a continuum version of the standard vortex-boson duality, calculate the speed of sound in the Cooper pair Wigner crystal and deduce the associated specific heat and thermal conductivity. We then suggest that these modes could be responsible for the mysterious bosonic contribution to the thermal conductivity recently observed in strongly underdoped ultraclean single crystals of YBCO tuned across the superconductor-insulator transition.Comment: 14 pages; 3 figures; corrected the sample size value; version 3 to appear in PR

Predators reduce extinction risk in noisy metapopulations

Background Spatial structure across fragmented landscapes can enhance regional population persistence by promoting local “rescue effects.” In small, vulnerable populations, where chance or random events between individuals may have disproportionately large effects on species interactions, such local processes are particularly important. However, existing theory often only describes the dynamics of metapopulations at regional scales, neglecting the role of multispecies population dynamics within habitat patches. Findings By coupling analysis across spatial scales we quantified the interaction between local scale population regulation, regional dispersal and noise processes in the dynamics of experimental host-parasitoid metapopulations. We find that increasing community complexity increases negative correlation between local population dynamics. A potential mechanism underpinning this finding was explored using a simple population dynamic model. Conclusions Our results suggest a paradox: parasitism, whilst clearly damaging to hosts at the individual level, reduces extinction risk at the population level

The Attractiveness of Ports in West Africa: Some Lessons from Shipping Lines' Port Selection

This paper investigates the attractiveness of ports in West Africa through the development of a container shipping lines' port choice methodology. Although many multi-criteria decision-making methods have been developed and applied to facilitate a rational port choice process, few have investigated the criteria used by shipping lines when selecting ports in West Africa. With the rapid economic development of West Africa, the task of establishing a rational model to guide shipping lines to choose their favourite ports in the region becomes urgent. In this work, 16 criteria are identified to assist shipping lines in port choice from four perspectives including adequate infrastructure, port location, port charge, and port administration/port efficiency. In order to quantitatively evaluate these criteria, an analytical hierarchy process approach is used to make use of subjective judgements to compensate the incompleteness of objective data. One of the important findings from this study is that port infrastructure is the most crucial criterion in terms of the port attractiveness in West Africa. It is followed by port draught, political stability, market size/cargo volume, and international networks. The research outcomes also indicate that the port of Abidjan is the most attractive container port in West Africa, followed by Dakar when all the identified important criteria are taken into account

Production and function of Neolithic black-painted pottery from Schela Cladovei (Iron Gates, Romania)

This paper presents for the first time the results of a combination of petrographic, geochemical and organic residue analyses of early Neolithic ceramics from the Iron Gates region of the Danube basin. Eleven early Neolithic potsherds from Schela Cladovei (Romania) were analysed in detail. The results of the petrographic analysis show that the ceramics were made with the same recipe that was used by Starčevo-Körös-Criș potters elsewhere in southeastern Europe. The SEM-EDX analysis shows one of the earliest uses of Mn-rich black pigments to decorate Neolithic European ceramics. Organic residue analyses detected dairy, non-ruminant and ruminant adipose fats. No evidence of aquatic resources was detected. In summary, the early Neolithic potters at the Iron Gates, although able to make coarse and more sophisticated painted ceramics, did not make specific vessels for a specific use

Unconventional Care: Offspring Abandonment and Filial Cannibalism Can Function as Forms of Parental Care

Parental care is a key life-history trait that increases offspring fitness. When one thinks of parental care, nurturing behaviors such as guarding, provisioning, and grooming typically come to mind. However, such conventional forms of care often co-occur with offspring abandonment or filial cannibalism (the consumption of one's offspring). Offspring abandonment and filial cannibalism are typically viewed as evolutionary conundrums that are contradictory to parental care. Here, we hypothesize that when offspring survival is density dependent, offspring abandonment and filial cannibalism can themselves function as forms of parental care for remaining offspring. We use a mathematical model to test this hypothesis. Our results suggest that offspring abandonment and filial cannibalism can function as forms of parental care. These results have the potential to broaden our general understanding of what is considered to be parental care

RADIOCARBON AND STABLE ISOTOPE EVIDENCE OF DIETARY CHANGE FROM THE MESOLITHIC TO THE MIDDLE AGES IN THE IRON GATES: NEW RESULTS FROM LEPENSKI VIR

This is the published version, also available here: https://journals.uair.arizona.edu/index.php/radiocarbon/article/view/4269.A previous radiocarbon dating and stable isotope study of directly associated ungulate and human bone samples from Late Mesolithic burials at Schela Cladovei in Romania established that there is a freshwater reservoir effect of approximately 500 yr in the Iron Gates reach of the Danube River valley in southeast Europe. Using the d15N values as an indicator of the percentage of freshwater protein in the human diet, the 14C data for 24 skeletons from the site of Lepenski Vir were corrected for this reservoir effect. The results of the paired 14C and stable isotope measurements provide evidence of substantial dietary change over the period from about 9000 BP to about 300 BP. The data from the Early Mesolithic to the Chalcolithic are consistent with a 2-component dietary system, where the linear plot of isotopic values reflects mixing between the 2 end-members to differing degrees. Typically, the individuals of Mesolithic age have much heavier d15N signals and slightly heavier d13C, while individuals of Early Neolithic and Chalcolithic age have lighter d15N and d13C values. Contrary to our earlier suggestion, there is no evidence of a substantial population that had a transitional diet midway between those that were characteristic of the Mesolithic and Neolithic. However, several individuals with Final Mesolithic 14C ages show d15N and d13C values that are similar to the Neolithic dietary pattern. Provisionally, these are interpreted either as incomers who originated in early farming communities outside the Iron Gates region or as indigenous individuals representing the earliest Neolithic of the Iron Gates. The results from Roman and Medieval age burials show a deviation from the linear function, suggesting the presence of a new major dietary component containing isotopically heavier carbon. This is interpreted as a consequence of the introduction of millet into the human food chain