1,038 research outputs found
Mass density vs. energy density at cosmological scales
In the presence of the gravitational field, the energy density of matter no
longer coincides with its mass density. A discrepancy exists, of course, also
between the associated power spectra. Within the CDM model, we derive
a formula that relates the power spectrum of the energy density to that of the
mass density and test it with the help of N-body simulations run in comoving
boxes of 2.816 Gpc/. The results confirm the validity of the derived formula
and simultaneously show that the power spectra diverge significantly from one
another at large cosmological scales.Comment: 10 pages, 4 figure
HAWT Rotor Design and Performance Analysis
Abstract In this paper, a design method based on blade element momentum (BEM) theory is explained for horizontal-axis wind turbine (HAWT) blades. The method is used to optimize the chord and twist distributions of the blades. Applying this method a 100kW HAWT rotor is designed. Also a computer program is written to estimate the aerodynamic performance of the existing HAWT blades and used for the performance analysis of the designed 100kW HAWT rotor
THE PSYCHOLOGICAL EFFECTS OF COVID 19 ON MEDICAL AND NON-MEDICAL UNIVERSITY STUDENTS
Background: The COVID 19 pandemic has had significant psychological effects on university students as well as in all segments
of society. The aim of this study is to examine the relationship between education fields (medical-non medical), education styles
(online-face to face), sociodemographic characteristics of university students and their levels of depression, anxiety, stress, fear of
COVID-19.
Subjects and methods: In the cross-sectional designed research, 1213 university students studying in Turkey was reached online.
A sociodemographic form, the Depression Anxiety Stress Scale (DASS 21) and the Fear of COVID-19 Scale (FCV-19S) was applied
to the participants.
Results: Of all participants 887(73%) were women. 647(53%) students were studying in the medical field. The scores of FCV-
19S and all subscales of DASS 21 were significantly higher in women. In the comparison between the field and style of education, no
difference was found. DASS 21 scores were higher in the participants whose relatives had COVID-19 or who had a mental disorder
in the past or medical disease.
Conclusions: In this study, it was observed that while there was no significant difference in the scores of DASS 21 among
university students in terms of the field and style of education, variables such as gender, not having COVID-19 so far, having lost a
relative due to COVID-19 could cause significant differences. Identifying sensitive groups will create early intervention
opportunities
THE PSYCHOLOGICAL EFFECTS OF COVID 19 ON MEDICAL AND NON-MEDICAL UNIVERSITY STUDENTS
Background: The COVID 19 pandemic has had significant psychological effects on university students as well as in all segments
of society. The aim of this study is to examine the relationship between education fields (medical-non medical), education styles
(online-face to face), sociodemographic characteristics of university students and their levels of depression, anxiety, stress, fear of
COVID-19.
Subjects and methods: In the cross-sectional designed research, 1213 university students studying in Turkey was reached online.
A sociodemographic form, the Depression Anxiety Stress Scale (DASS 21) and the Fear of COVID-19 Scale (FCV-19S) was applied
to the participants.
Results: Of all participants 887(73%) were women. 647(53%) students were studying in the medical field. The scores of FCV-
19S and all subscales of DASS 21 were significantly higher in women. In the comparison between the field and style of education, no
difference was found. DASS 21 scores were higher in the participants whose relatives had COVID-19 or who had a mental disorder
in the past or medical disease.
Conclusions: In this study, it was observed that while there was no significant difference in the scores of DASS 21 among
university students in terms of the field and style of education, variables such as gender, not having COVID-19 so far, having lost a
relative due to COVID-19 could cause significant differences. Identifying sensitive groups will create early intervention
opportunities
Suppression of matter density growth at scales exceeding the cosmic screening length
One of the main objectives of modern cosmology is to explain the origin and
evolution of cosmic structures at different scales. The principal force
responsible for the formation of such structures is gravity. In a general
relativistic framework, we have shown that matter density contrasts do not grow
over time at scales exceeding the cosmic screening length, which corresponds to
a cosmological scale of the order of two to three gigaparsecs at the present
time, at which gravitational interactions exhibit an exponential cut-off. This
is a purely relativistic effect. To demonstrate the suppression of density
growth, we have performed N-body simulations in a box with a comoving size of
and obtained the power spectrum of the mass density
contrast. We have shown that it becomes independent of time for scales beyond
the cosmic screening length as a clear manifestation of the cosmic screening
effect.Comment: 7 pages, 3 figure
A quantitative analysis of the effect of box size in N-body simulations of the matter power spectrum
We study the effect of box size on the matter power spectrum obtained via
cosmological N-body simulations. Within the framework of the cosmic screening
approach, we show that the relative deviation between the spectra for our
largest comoving box with L = 5632 Mpc/h and those for L = 280, 560, 1680,
4480, 5120 Mpc/h boxes consistently increases with decreasing box size in the
latter set in the redshift range for the considered values. As
an additional demonstrative example, at redshift zero, we determine the values
corresponding to the modes at which relative deviations reach 1\%.Comment: 8 pages, 2 tables, 3 figure
DIŞ KAYNAK KULLANIMI AÇISINDAN INFLUENCER'LARIN GÜCÜ: INSTAGRAM ÖRNEĞİ
ÖZ: Gelişen teknolojik imkânlar, firmalara faaliyetlerini dijital ortamlara taşıması için büyük fırsatlar sunmaktadır. Bu fırsatlar firmaların geleneksel pazarlama faaliyetlerinden, dijital pazarlama faaliyetlerine geçiş süreçlerini pozitif yönde etkilemektedir. Özellikle sosyal medya platformları gibi çift yönlü iletişimin çok güçlü olduğu mecralarda, dijital pazarlama faaliyetleri her geçen gün önem kazanmaktadır. Bazı firmalar, bu mecraları kullanan bireylere ulaşabilmek için influencerlarla işbirliği içine girmekte ve dış kaynak kullanımını dijital platformlara da taşımaktadır. Bu noktadan yola çıkarak çalışmanın amacı; “Black Friday, Şahane Cuma, Efsane Kasım, Muhteşem Cuma ve Cyber Monday”
gibi kampanyaların yer aldığı kasım ayı boyunca influencerların story ve post paylaşımlarından hareketle firma ve influencer işbirliğini çeşitli yönlerden açıklamaya çalışmaktır. Bu doğrultuda Kasım ayı boyunca düzenli olarak paylaşım yapan 15 influencerın, Instagram hesaplarında takipçileri ile paylaştıkları story ve postlar günlük takip edilmiş ve işbirliği içinde olduğu marka ve ürünler belirlenmiştir. Elde edilen sonuçlar, firmaların ürün ve hizmet tanıtımlarımda influencerlar ile önemli bir işbirliği içerisinde olduğunu, seçilen influencerlar ile ürün ve hizmet özelliklerinin de özenli ve birbiri ile örtüşen içerikler ile sağlandığı görülmektedir.
ABSTRACT: Developing technological opportunities provide businesses with numerous opportunities to shift their operations to digital environments. These opportunities have a positive impact on companies' transition processes from traditional marketing activities to digital marketing activities. Digital marketing activities are becoming increasingly important, particularly in channels with strong two-way communication, such as social media platforms. Companies work with influencers to reach out to individuals through these channels, and they outsource to digital platforms. From this point, the study's goal is
to attempt to explain how the company and influencer collaborated from various angles, based on the influencers' posts and shares during the month of November, when campaigns
like "Black Friday, Wonderful Friday, Legendary November, Great Friday and Cyber Monday" were active. In this manner, the Instagram stories and posts of 15 influencers who regularly shared content with their followers throughout the month of November were monitored on a daily basis, and the brands and products with which they collaborated were identified. The obtained results indicate that companies work closely with influencers to promote their products and services, and that the selected influencers and product and service features are provided with content that overlaps with care
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