Mechanical effects on atoms interacting with highly twisted Laguerre-Gaussian light

Laguerre-Gaussian (LG) light modes with large values of the radial index p and the azimuthal index l are considered. We give special emphasis on the mechanical effects on atoms arising from the Gouy phase and the phase due to the curvature of such light. It is shown that the additional phase terms for highly twisted light can lead to mechanical effects based on the substantial reduction of the axial wavenumber. As a consequence, axial recoil effects are diminished in the processes of stimulated emission and absorption of the light by the atoms. Both the scattering force and the momentum diffusion are affected by the inclusion of these normally ignored additional phase terms. The magnitudes of the effects are explored using order of magnitude analysis with typical parameters due to the atoms and the light

Interference of axially-shifted Laguerre–Gaussian beams and their interaction with atoms

Counter-propagating co-axial Laguerre–Gaussian (LG) beams are considered, not in the familiar scenario where the focal planes coincide at z = 0, but when they are separated by a finite axial distance d. The simplest case is where both beams are doughnut beams which have the same linear polarisation. The total fields of this system are shown to display novel amplitude and phase distributions and are shown to give rise to a ring or a finite ring lattice composed of double rings and single central ring. When the beams have slightly different frequencies the ring lattice pattern becomes a finite set of rotating Ferris wheels and the whole pattern also moves axially between the focal planes. We show that the fields of such an axially shifted pair of counter-propagating LG beams generate trapping potentials due to the dipole force which can trap two-level atoms in the components of the ring lattice. We also highlight a unique feature of this system which involves the creation of a new longitudinal optical atom trapping potential due to the scattering force which arises solely when $d\ne 0$. The results are illustrated using realistic parameters which also confirm the importance of the Gouy and curvature effects in determining the ring separation both radially and axially and gives rise to the possibility of atom tunnelling between components of the double rings

Atoms in complex twisted light

The physics of optical vortices, also known as twisted light, is now a well-established and a growing branch of optical physics with a number of important applications and significant inter-disciplinary connections. Optical vortex fields of widely varying forms and degrees of complexity can be realised in the laboratory by a host of different means. The interference between such beams with designated orbital angular momenta and optical spins (the latter is associated with wave polarisations) can be structured to conform to various geometrical arrangements. The focus of this review is on how such tailored forms of light can exert a controllable influence on atoms with which they interact. The main physical effects involve atoms in motion due to application of optical forces. The now mature area of atom optics has had notable successes both of fundamental nature and in applications such as atom lasers, atom guides and Bose–Einstein condensates. The concepts in atom optics encompass not only atomic beams interacting with light, but atomic motion in general as influenced by optical and other fields. Our primary concern in this review is on atoms in structured light where, in particular, the twisted nature of the light is made highly complex with additional features due to wave polarisation. These features bring to the fore a variety of physical phenomena not realisable in the context of atomic motion in more conventional forms of laser light. Atoms near resonance with such structured light fields become subject to electromagnetic fields with complex polarisation and phase distributions, as well as intricately structured intensity gradients and radiative forces. From the combined effect of optical spin and orbital angular momenta, atoms may also experience forces and torques involving an interplay between the internal and centre of mass degrees of freedom. Such interactions lead to new forms of processes including scattering, trapping and rotation and, as a result, they exhibit characteristic new features at the micro-scale and below. A number of distinctive properties involving angular momentum exchange between the light and the atoms are highlighted, and prospective applications are discussed. Comparison is made between the theoretical predictions in this area and the corresponding experiments that have been reported to date

Comparison of magnetized and normal water on yield and yield components of banana and hydraulic performance of drip irrigation system

     An experiment was conducted at the Horticultural Research Centre Farm of the Agricultural Research Corporation (ARC), Wad Medani, Sudan during seasons 2010 through 2012 to evaluate effects of magnetic water technology on yield, and yield components of banana cv. Albeily and hydraulics of drip irrigation system. Two types of irrigation water were used: magnetic water and normal water. The plot of each type of irrigation water consisted of 4 banana plants. The two treatments were replicated 5 times. The results revealed that applying magnetic water increased plant height and girth of banana and attained fewer days from planting to flowering and from flowering to harvest compared to normal water. Bunch weight and number of hands per bunch were also higher for magnetic water.  Magnetic water improved the hydraulic performance of drip irrigation system compared to normal water.        اجريت هذه الدراسة بمزرعة مركز بحوث البساتين، هيئة البحوث الزراعية، واد مدني السودان في الفترة من 2010 وحتي 2012 لتقييم أثر تقنية مغنطة المياه على الانتاجية  ومكونات انتاجية الموز والاداء الهيدرولوكي للري بالتنقيط صنف البيلي. استخدم نوعين من مياه الري مياه ممغنطة ومياه عادية. الوحدة في كل نوع من مياه الري ضمت اربع نباتات والمعاملتين تم تكرارها خمس مرات. اظهرت النتائج ان المياه الممغنطة ادت الي زياده في طول وسمك الساق الكاذبة للموز وكذلك الي تقليل الايام من الزراعة الي الازهار ومن الازهار الي الحصاد. كما اظهرت النتائج ان وزن السبيطة وعدد الكفوف في السبيطة كان اعلي تحت المياه الممغنطة. أدت مغنطة مياه الري الي تحسين الاداء الهيدرولوكي لنظام الري بالتنقيط مقارنة مع المياه العادية.  &nbsp

Even-odd effect in higher-order holographic production of electron vortex beams with nontrivial radial structure

Structured electron beams carrying orbital angular momentum are currently of considerable interest, both from a fundamental point of view and for application in electron microscopy and spectroscopy. Until recently, most studies have focused on the azimuthal structure of electron vortex beams with well-defined orbital angular momentum. To unambiguously define real electron-beam states and realise them in the laboratory, the radial structure must also be specified. Here we use a specific set of orthonormal modes of electron (vortex) beams to describe both the radial and azimuthal structures of arbitrary electron wavefronts. The specific beam states are based on truncated Bessel beams localised within the lens aperture plane of an electron microscope. We show that their Fourier transform set of beams can be realised at the focal planes of the probe-forming lens using a binary computer generated electron hologram. Using astigmatic transformation optics, we demonstrate that the azimuthal indices of the diffracted beams scale with the order of the diffraction through phase amplification. However, their radial indices remain the same as those of the encoding beams for all the odd diffraction orders or are reduced to the zeroth order for the even-order diffracted beams. This simple even-odd rule can also be explained in terms of the phase amplification of the radial profiles. We envisage that the orthonormal cylindrical basis set of states could lead to new possibilities in phase contrast electron microscopy and spectroscopy using structured electron beams

Detection of schistosomiasis antibodies in urine patients as a promising diagnostic maker

AbstractObjectiveTo determine secreted antischistosoma antibodies in urine and to discern the epidemiological situation of schistosomiasis in the agricultural field labourers'camps city in the Gezira State-central Sudan.MethodsTotal of 66 urine and 66 serum paired samples were collected from those who confirmed parasitologically positive and negative with schistosomiasis from the two camps. Samples were tested using ELISA technique to measure and compare the immunoglobulin G (IgG) levels in serum and urine samples of schistosomiasis patients.ResultsThe overall prevalence of S. mansoni and S. haematobium was 53.8% and 15.4%, while the intensity were (2.04 GMEC) and (0.9 GMEC) respectively. The relative percentage of positive IgG individulas in urine was 92.40% where as 96.97% in serum. Statistically no significant difference between the IgG levels in serum and urine samples was observed.ConclusionsThis study shows that the detection of secreted IgG antibodies in urine can substitute serum for diagnosis of schistosomiasis