Ge quantum dot arrays grown by ultrahigh vacuum molecular beam epitaxy on the Si(001) surface: nucleation, morphology and CMOS compatibility

Issues of morphology, nucleation and growth of Ge cluster arrays deposited by ultrahigh vacuum molecular beam epitaxy on the Si(001) surface are considered. Difference in nucleation of quantum dots during Ge deposition at low (<600 deg C) and high (>600 deg. C) temperatures is studied by high resolution scanning tunneling microscopy. The atomic models of growth of both species of Ge huts---pyramids and wedges---are proposed. The growth cycle of Ge QD arrays at low temperatures is explored. A problem of lowering of the array formation temperature is discussed with the focus on CMOS compatibility of the entire process; a special attention is paid upon approaches to reduction of treatment temperature during the Si(001) surface pre-growth cleaning, which is at once a key and the highest-temperature phase of the Ge/Si(001) quantum dot dense array formation process. The temperature of the Si clean surface preparation, the final high-temperature step of which is, as a rule, carried out directly in the MBE chamber just before the structure deposition, determines the compatibility of formation process of Ge-QD-array based devices with the CMOS manufacturing cycle. Silicon surface hydrogenation at the final stage of its wet chemical etching during the preliminary cleaning is proposed as a possible way of efficient reduction of the Si wafer pre-growth annealing temperature.Comment: 30 pages, 11 figure

Sensitive Chemical Compass Assisted by Quantum Criticality

The radical-pair-based chemical reaction could be used by birds for the navigation via the geomagnetic direction. An inherent physical mechanism is that the quantum coherent transition from a singlet state to triplet states of the radical pair could response to the weak magnetic field and be sensitive to the direction of such a field and then results in different photopigments in the avian eyes to be sensed. Here, we propose a quantum bionic setup for the ultra-sensitive probe of a weak magnetic field based on the quantum phase transition of the environments of the two electrons in the radical pair. We prove that the yield of the chemical products via the recombination from the singlet state is determined by the Loschmidt echo of the environments with interacting nuclear spins. Thus quantum criticality of environments could enhance the sensitivity of the detection of the weak magnetic field.Comment: 4 pages, 3 figure

Kualitas Hidup Pasien Pascaintervensi Koroner Perkutan

Coronary heart disease is a disease that can threaten person\u27s life, and can lead to the change of the quality of life. This coronary heart disease can be solved with non-surgical called percutaneous coronary intervention. This action will be normalized the quality of perfusion in the coronary arteries, which would certainly have an impact on the quality of life of patients. The research objective was to observe the patient of quality of life after treatment on intervention percutaneous coronary. The research design was cross sectional. There were 50 respondents taken by consecutive sampling. Data were collected in outpatient room in RSUP Dr. Hasan Sadikin Bandung, who have came with treatment routine schedule after percutaneous coronary intervention during November 1st–14th 2013. The questionnaire use WHOQOL-BREF format with 26 questions that consisting of 4 domains of quality of life: physical domain, psychological domain, social domain, and environment domain. Majority of patients were male (74 %), with the range of age mostly 56-66 years ( 34 % ), married ( 96 % ), college education was the highest ( 66 % ), the majority had not a primary job like as housewife , retired, student, etc. ( 26 % ). Data were collected using the questionnaire WHOQOL – BREF. The result have shown that rates of quality of life was good ( 50 % ) and health condition after percutaneous coronary intervention neither satisfied nor dissatisfied ( 44 % ). Nurses have a role in helping patients achieve optimal quality of life like giving information to patient correctl

Efficiency optimization in a correlation ratchet with asymmetric unbiased fluctuations

The efficiency of a Brownian particle moving in periodic potential in the presence of asymmetric unbiased fluctuations is investigated. We found that there is a regime where the efficiency can be a peaked function of temperature, which proves that thermal fluctuations facilitate the efficiency of energy transformation, contradicting the earlier findings (H. kamegawa et al. Phys. Rev. Lett. 80 (1998) 5251). It is also found that the mutual interplay between asymmetry of fluctuation and asymmetry of the potential may induce optimized efficiency at finite temperature. The ratchet is not most efficiency when it gives maximum current.Comment: 10 pages, 7 figure

On the Stability and Structural Dynamics of Metal Nanowires

This article presents a brief review of the nanoscale free-electron model, which provides a continuum description of metal nanostructures. It is argued that surface and quantum-size effects are the two dominant factors in the energetics of metal nanowires, and that much of the phenomenology of nanowire stability and structural dynamics can be understood based on the interplay of these two competing factors. A linear stability analysis reveals that metal nanocylinders with certain magic conductance values G=1, 3, 6, 12, 17, 23, 34, 42, 51, 67, 78, 96, ... times the conductance quantum are exceptionally stable. A nonlinear dynamical simulation of nanowire structural evolution reveals a universal equilibrium shape consisting of a magic cylinder suspended between unduloidal contacts. The lifetimes of these metastable structures are also computed.Comment: 8 pages, 6 figure

Evaluasi Tahan Banjir Padi Lokal Sulawesi Utara pada Fase Vegetatif dengan Variasi Waktu Perendaman

Banjir merupakan salah satu kendala yang menghambat produktivitas padi. Masalah ini dapat diselesaikan dengan beberapa cara, salah satunya dengan strategi adaptasi. Oleh karena itu perlu dilakukan kajian tentang adaptasi banjir khusunya pada padi lokal Sulawesi Utara (Superwin, Burungan, Temo dan Ombong). Penelitian telah dilaksanakan untuk mengakaji pengaruh cekaman banjir terhadap padi lokal Sulawesi Utara pada fase vegetatif. Penelitian ini dilakukan dengan 4 varietas padi lokal Sulawesi Utara (Superwin, Ombong, Temo dan Burungan) dengan 12 kali ulangan dan perlakuan dilakukan pada saat padi berusia 2 minggu. Perlakuannya yaitu dengan membanjiri tanaman padi yang berusia 2 minggu hingga hari ke-20. Dari hasil penenlitian ini tinggi tanaman dari keempat varietas padi lokal Sulawesi Utara sama-sama menunjukkan pertumbuhan yang baik sehingga bisa dijadikan indikator padi yang tahan banjir. Berdasarkan jumlah daun dari keempat varietas varietas Superwin yang memiliki daun terbanyak dibanding dengan ketiga varietas lainnya, namun secara keseluruhan dari jumlah daun setiap varietas bisa bertahan dalam banjir sehingga bisa dipakai sebagai indikator padi yang tahan banjir

Individualised headband simulation test for predicting outcome after percutaneous bone conductive implantation.

Trans-cutaneous bone conduction (BC) stimulators, when coupled to the HB (BC-HB), are generally used to predict the results that could be achieved after bone conductive implant (BCI) surgery, and their performance is generally considered inferior to that provided by the definitive percutaneous system. The aim of the present study was to compare the performances between BC-HB and BCI of the same typology, when the former's sound processor is fitted in accordance to the individual auditory situation. Twenty-two patients selected for surgical application of a BCI were evaluated and the same audiological protocol was used to select the candidate and assess the final outcome. The BC-HB was properly fitted based on individual hearing loss and personal auditory targets, and tested as primary step of the protocol to obtain the most reliable predictive value. The BAHA Divino and BP100 sound processors were applied in 12 patients with conductive/mixed hearing loss (CMHL) and in 10 subjects with single sided deafness (SSD). Audiometric evaluation included the pure tone average (PTA3) threshold between 250-1000 Hz; the PTA thresholds at 2000 and 4000 Hz; intelligibility scores as percentage of word recognition (WRS) in quiet and in noise; and subjective evaluation of perceived sound quality by a visual analogue scale (VAS). Statistical evaluation with a student's t test was used for assessment of efficacy of BC-HB and BCI compared with the unaided condition. Spearman's Rho coefficient was used to confirm the reliability of the BC-HB simulation test as a predictor of definitive outcome. The results showed that the mean PTA difference between BCI and BC-HB ranged from 2.54 to 8.27 decibels in the CMHL group and from 1.27 to 3.9 decibels in the SSD group. Compared with the BC-HB, BCI showed a better WRS both in CMHL (16% in quiet and 12% in noise) and in SSD (5% in quiet and a 1% in noise) groups. Spearman's Rho coefficient, calculated for PTA, WRS in quiet and in noise and VAS in the two aided conditions, showed a significant correlation between BC-HB and BCI, between PTA and VAS and between WRS in quiet and VAS. It is possible to conclude that the headband test, when the sound processor of the selected bone conductive implant is fitted and personalised for individual hearing loss and auditory targets of the candidate, may provide highly predictive data of the definitive outcome after BCI implant surgery

Cleaning up the cosmological constant

We present a novel idea for screening the vacuum energy contribution to the overall value of the cosmological constant, thereby enabling us to choose the bare value of the vacuum curvature empirically, without any need to worry about the zero-point energy contributions of each particle. The trick is to couple matter to a metric that is really a composite of other fields, with the property that the square-root of its determinant is the integrand of a topological invariant, and/or a total derivative. This ensures that the vacuum energy contribution to the Lagrangian is non-dynamical. We then give an explicit example of a theory with this property that is free from Ostrogradski ghosts, and is consistent with solar system physics and cosmological tests.Comment: 8 pages, typos corrected and more text added, version accepted for publication in JHE