The stochastic axiverse

In addition to spectacular signatures such as black hole superradiance and the rotation of CMB polarization, the plenitude of axions appearing in the string axiverse may have potentially dangerous implications. An example is the cosmological overproduction of relic axions and moduli by the misalignment mechanism, more pronounced in regions where the signals mentioned above may be observable, that is for large axion decay constant. In this work, we study the minimal requirements to soften this problem and show that the fundamental requirement is a long period of low-scale inflation. However, in this case, if the inflationary Hubble scale is lower than around O(100) eV, no relic DM axion is produced in the early Universe. Cosmological production of some axions may be activated, via the misalignment mechanism, if their potential minimum changes between inflation and today. As a particular example, we study in detail how the maximal-misalignment mechanism dilutes the effect of dangerous axions and allows the production of axion DM in a controlled way. In this case, the potential of the axion that realises the mechanism shifts by a factor ∆θ = π between the inflationary epoch and today, and the axion starts to oscillate from the top of its potential. We also show that axions with masses ma ∼ O(1 − 100) H0 realising the maximal-misalignment mechanism generically behave as dark energy with a decay constant that can take values well below the Planck scale, avoiding problems associated to super-Planckian scales. Finally, we briefly study the basic phenomenological implications of the mechanism and comment on the compatibility of this type of maximally-misaligned quintessence with the swampland criteria.

Reasons for Pack Size Purchase among US Adults Who Purchase Cigars

With municipalities across the US establishing minimum cigar pack size regulations, it is critical to understand what drives pack size preference. The purpose of this exploratory study was to identify reasons for cigar pack size purchase. We used Amazon’s Mechanical Turk to survey adults who had purchased cigars and reported past 30 day use. Participants responded to an open-ended item asking their reasons for purchasing their usual pack size. Responses were double-coded and categorized. Of 152 respondents, 61 used traditional cigars, 85 used cigarillos, and 36 used filtered cigars. Across all cigar types, most participants (73.7%) purchased boxes rather than singles; 5–9-packs were the most popular pack size category (19.7%), followed by 20+-packs (18.4%). We identified 16 reasons for pack size purchase across seven categories: price, consumption, social aspect, convenience, product characteristics, availability, and general preferences. Reasons varied according to whether the consumer purchased larger or smaller pack sizes. In this exploratory study to identify reasons for cigar pack size purchases, findings were consistent with those identified through tobacco industry documents and in the cigarette literature. Future research should examine the prevalence of these reasons, including as a function of demographic and use characteristics, to help inform the understanding of potential minimum cigar pack regulations.

Switchable positioning of plate-like inclusions in lipid membranes: Elastically mediated interactions of planar colloids in 2D fluids

We demonstrate how manipulating curvature in an elastic fluid lamella enables the reversible relative positioning of flat, rigid, plate-like micrometer-scale inclusions, with spacings from about a micrometer to tens of micrometers. In an experimental model comprising giant unilamellar vesicles containing solid domain pairs coexisting in a fluid membrane, we adjusted vesicle inflation to manipulate membrane curvature and mapped the interdomain separation. A two-dimensional model of the pair potential predicts the salient experimental observations and reveals both attractions and repulsions, producing a potential minimum entirely a result of the solid domain rigidity and bending energy in the fluid membrane. The impact of vesicle inflation on domain separation in vesicles containing two solid domains was qualitatively consistent with observations in vesicles containing many domains. The behavior differs qualitatively from the pure repulsions between fluid membrane domains or interactions between nanoscopic inclusions whose repulsive or attractive character is not switchable.

INHIBITORY EFFECTS OF POD EXTRACT OF ACACIA NILOTICA AGAINST SOME PATHOGENIC BACTERIA

This study assessed the inhibitory effects of the pod extract of Acacia nilotica against some pathogenic bacteria (Escherichia coli, Klebsiella pneumoniae, Proteus mirabilis, Pseudomonas aeruginosa, Staphylococcus aureus, Streptococccus pyogenes). Fresh pods of Acacia nilotica were air-dried and then ground into fine powder. Thereafter, pod powder was extracted using ethanol and distilled water in the ratio 3 to 2 (v/v). The crude extract was concentrated in vacuo and lyophilized. Afterwards, screened for phytochemicals and tested for antibacterial activity against the bacterial isolates. Antibacterial potential, minimum inhibitory concentrations (MIC), and minimum bactericidal concentrations (MBC) of the extract were determined using standard microbiological method. Zone of inhibition shown by the crude extract at 50 mg/mL on the isolates ranged between 10 mm and 18 mm while MIC ranged between 1.56 mg/mL and 25 mg/mL. Minimum bactericidal concentrations ranged between 3.13 mg/mL and 50.00 mg/mL. The phytochemical screening of the extract revealed the presence of tannins, alkaloids, flavonoids, saponins and cardiac glycosides. This study, therefore, showed that pod extract of Acacia nilotica exhibited appreciable inhibitory effects on the test isolates. Hence, there is need for in vivo studies to complement the present findings.

Enforced Social Isolation and Risk of Death in Elderly People in Cyprus

Social isolation is associated with a higher risk of death in older people. The quarantine and social distancing measures due to Covid-19 imposed in Cyprus from the beginning of the pandemic, aim to isolate individuals from direct contact with others. This has resulted in vulnerable older people being isolated at their places of residence for several weeks, while the recommendation by some experts is a potential minimum isolation period of three to four months. The risk of death from causes other than those related to Covid-19, increases in such individuals, and it is due to the effects of social isolation. We estimate that in the next year, there will be an increase in the death numbers of such older people in Cyprus, reaching a minimum 200 extra deaths a year, for every three months of isolation. The health authorities must develop a program of support for these older individuals to include medical, social, cognitive, physical and psychological elements. Examples of such support are given here.

Is Symmetry Breaking into Special Subgroup Special?

The purpose of this paper is to show that symmetry breaking into special subgroups is not special at all, contrary to the usual wisdom. To demonstrate this explicitly, we examine the dynamical symmetry breaking pattern in four-dimensional $SU(N)$ Nambu–Jona-Lasinio-type models in which the fermion matter belongs to an irreducible representation of $SU(N)$. Potential analysis shows that for almost all cases at the potential minimum the $SU(N)$ group symmetry is broken to its special subgroups such as $SO(N)$ or ${USp}(N)$ when symmetry breaking occurs.

Theoretical study on the ability of bicyclic cryptands to separate alkali-metal isotopes by ion exchange

Cryptand [2.2.2] collects heavier isotope 137Cs more readily than [3.2.2] that gives a potential minimum at d = de.

Effect of Substrate Shape on Friction Regimes and on Tip Jump Probability in Atomic Scale Friction

We investigate the effect of the shape potential on the frictional behavior transitions. The Tomlinson parameter for the deformable substrate potential is calculated theoretically and its influence on friction force is studied. Futhermore, effects of temperature and substrate shape on the tip jump probability are presented. We find two critical times, which characterize the tip dynamics. The first critical time is the time spent by the tip to reach next potential minimum and the second is the time at which the tip exhibits an equiprobability of forward and backward jump. We show that these critical times depend strongly on the substrate shape as well as on the temperature.

Minimalmengenschmierung/Minimum Quantity Lubrication - Feature-based cost and effort analysis for drilling processes in aluminum alloys

Angesichts der steigenden Relevanz ökologisch nachhaltiger Produktion steht unter anderem die Kühlschmierstoffversorgung im Fokus von Ressourceneffizienzmaßnahmen. Ein Befähiger zur Hebung von Effizienzpotentialen ist die seit Mitte der 1990er Jahre untersuchte Minimalmengenschmierung (MMS). Der Fachbeitrag beschreibt die Analyse der monetären sowie technologischen Aufwände der Einführung von Minimalmengenschmierung in Bohrprozesse in Aluminiumbauteilen am Beispiel der Automobilindustrie.   Due to the increasing relevance of ecologic sustainable production, the resource efficient design of cooling lubricant supply systems, among others, is at focus. Being an enabler for exploiting the efficiency potential, minimum quantity lubrication technology (MQL) is investigated since the mid-nineties of the last century. This contribution analyses the economic and technologic impact of the introduction of MQL to drilling processes in aluminum alloys using the automotive industry as an example.