Volume 5, Issue 8, August 2021

Calcium and its Protein Binding in Lactation in Mammary Gland and Blood Clotting

D.K.Awasthi Meet Kamal

Volume 5, Issue 8, August, PP  1-4

Aquaculture Monitoring With Machine Learning Technique

Shailesh Kumar Vivek Kumar

Volume 5, Issue 8, August, PP  5-8

A Study on Impact of Union Budget 2021-22 on MSMEs in India

Dr. S. Gautami Ms. M. Sravani

Volume 5, Issue 8, August, PP  9-13

Influence of Treatment with Different Levels and Periods of Temperature on Dormancy and Sprouting of Tubers of Some Potato Varieties

Dr. Rida DRAIE Abdul-Mohsen AL-ALI

Volume 5, Issue 8, August, PP  14-24

Maintenance of Health and Safety of Women Garment Employees: A Study of Chittagong Asian Apparels Ltd

Prof. Mihir Kumar Roy Ph.D Md. Shakil Fatema Tuz Zohora

Volume 5, Issue 8, August, PP  25-33

Application of Relative Importance Index for Assessment of On-Site Labour Productivity

Anil S. Parlikar Kalpeshkumar M. Sharma

Volume 5, Issue 8, August, PP  34-39

New Structural Economic Perspective: The Case of Sierra Leone

Dr. Joseph Davies

Volume 5, Issue 8, August, PP  40-49

Political Philosophy Politics of Identity and Political Order in Developing Countries

Dr. Joseph Davies

Volume 5, Issue 8, August, PP  50-55

Crack Growth Study in Welded Sheet Metal

José L. Ramírez Cruz Homero Jiménez Rabiela Benjamín Vázquez González Gustavo A. Bravo Acosta Pedro García Segura

Volume 5, Issue 8, August, PP  56-60

Navigation System for Blind Using QR Code

Vedang Chavan Shreyasi Watve Mugdha Kango Vineet Borse Khushal Rathod

Volume 5, Issue 8, August, PP  61-64

Development of a Knowledge Discovery System in Big Data Mining Environment

Ihekeremma A. U. Ejimofor Obi O.R. Okonkwo

Volume 5, Issue 8, August, PP  65-70

Cognitive Radio

Anuj Sarode Priyanka Ojha

Volume 5, Issue 8, August, PP  71-74

Behavior of Deep Beams using Different Concrete Grades

Noha Ahmed Metwally Ahmed Prof. Ayman Hussein Hosny Khalil Dr. Ezz El-deen Mostafa

Volume 5, Issue 8, August, PP  75-81

Performance Assessment of Multi-node Parallel Computing System from First-principles

Mohammed B Wante H.P Hayatu A

Volume 5, Issue 8, August, PP  82-87

Determination of Pesticide Residue in Dug Well and Borehole in Yawa Drinking Water Adamawa State, Nigeria

Ismaila Yada Sudi Isa Usman Samuel Tinema Magili Maryam Usman Ahmed Clifford Liki Barnabas Asiyina Elihu

Volume 5, Issue 8, August, PP  88-93

A Newly Proposed Ambidextrous Software Testing Model Based on Conventional Black Box Testing Strategy Using the Applications of Gaussian Distribution

Shivankur Thapliyal Renu Bahuguna

Volume 5, Issue 8, August, PP  94-101

Developing a Low-Cost Salinity Sensor Using Locally Sourced Materials

Okunlola B.A. Ewetumo T. Okogbue E. C. Olabanji O. M.

Volume 5, Issue 8, August, PP  102-106

Forecasting Total Fertility Rate (TFR) In Comoros

Dr. Smartson. P. NYONI Tatenda. A. CHIHOHO Thabani NYONI

Volume 5, Issue 8, August, PP  107-110

Forecasting Total Fertility Rate (TFR) in the Kingdom of Eswatini

Dr. Smartson. P. NYONI Tatenda. A. CHIHOHO Thabani NYONI

Volume 5, Issue 8, August, PP  111-114

Projection of Total Fertility Rate (TFR) in the Democratic Republic of Congo

Dr. Smartson. P. NYONI Tatenda. A. CHIHOHO Thabani NYONI

Volume 5, Issue 8, August, PP  115-118

Projection of Total Fertility Rate (TFR) in Brazil

Dr. Smartson. P. NYONI Tatenda. A. CHIHOHO Thabani NYONI

Volume 5, Issue 8, August, PP  119-122

Forecasting Total Fertility Rate (TFR) in Eritrea Using a Machine Learning Technique

Dr. Smartson. P. NYONI Tatenda. A. CHIHOHO Thabani NYONI

Volume 5, Issue 8, August, PP  123-126

Forecasting Total Fertility Rate (TFR) in Cameroon

Dr. Smartson. P. NYONI Tatenda. A. CHIHOHO Thabani NYONI

Volume 5, Issue 8, August, PP  127-130

Forecasting Total Fertility Rate (TFR) in Benin Using a Machine Learning Algorithm

Dr. Smartson. P. NYONI Tatenda. A. CHIHOHO Thabani NYONI

Volume 5, Issue 8, August, PP  131-134

Forecasting Total Fertility Rate (TFR) in Cote d’lvoire using a Machine Learning Technique

Dr. Smartson. P. NYONI Tatenda. A. CHIHOHO Thabani NYONI

Volume 5, Issue 8, August, PP  135-138

Forecasting Total Fertility Rate (TFR) in Egypt

Dr. Smartson. P. NYONI Tatenda. A. CHIHOHO Thabani NYONI

Volume 5, Issue 8, August, PP  139-142

Forecasting Total Fertility Rate (TFR) in Congo Using the Multilayer Perceptron

Dr. Smartson. P. NYONI Tatenda. A. CHIHOHO Thabani NYONI

Volume 5, Issue 8, August, PP  143-146

Forecasting Total Fertility Rate (TFR) in Bangladesh

Dr. Smartson. P. NYONI Tatenda. A. CHIHOHO Thabani NYONI

Volume 5, Issue 8, August, PP  147-150

Forecasting Total Fertility Rate (TFR) in Carbo Verde

Dr. Smartson. P. NYONI Tatenda. A. CHIHOHO Thabani NYONI

Volume 5, Issue 8, August, PP  151-154

Forecasting Total Fertility Rate (TFR) in Chad Using a Machine Learning Approach

Dr. Smartson. P. NYONI Tatenda. A. CHIHOHO Thabani NYONI

Volume 5, Issue 8, August, PP  155-158

Forecasting Total Fertility Rate (TFR) In Burundi

Dr. Smartson. P. NYONI Tatenda. A. CHIHOHO Thabani NYONI

Volume 5, Issue 8, August, PP  159-162

Forecasting Total Fertility Rate (TFR) in Ethiopia

Dr. Smartson. P. NYONI Tatenda. A. CHIHOHO Thabani NYONI

Volume 5, Issue 8, August, PP  163-166

Projection of Total Fertility Rate (TFR) in China Using an Artificial Intelligence Technique

Dr. Smartson. P. NYONI Tatenda. A. CHIHOHO Thabani NYONI

Volume 5, Issue 8, August, PP  167-170

Projection of Total Fertility Rate (TFR) in Djibouti

Dr. Smartson. P. NYONI Tatenda. A. CHIHOHO Thabani NYONI

Volume 5, Issue 8, August, PP  171-174

Forecasting Total Fertility Rate (TFR) in Botswana

Dr. Smartson. P. NYONI Tatenda. A. CHIHOHO Thabani NYONI

Volume 5, Issue 8, August, PP  175-178

Total Fertility Rate (TFR) Forecasting in Burkina Faso

Dr. Smartson. P. NYONI Tatenda. A. CHIHOHO Thabani NYONI

Volume 5, Issue 8, August, PP  179-182

Forecasting Total Fertility Rate in the Central African (CAF) Republic

Dr. Smartson. P. NYONI Tatenda. A. CHIHOHO Thabani NYONI

Volume 5, Issue 8, August, PP  183-186

Projection of Total Fertility Rate (TFR) in Equatorial Guinea

Dr. Smartson. P. NYONI Tatenda. A. CHIHOHO Thabani NYONI

Volume 5, Issue 8, August, PP  187-190

Forecasting Total Fertility Rate (TFR) in Ecuador Using a Machine Learning Algorithm

Dr. Smartson. P. NYONI Tatenda. A. CHIHOHO Thabani NYONI

Volume 5, Issue 8, August, PP  191-194

Forecasting Total Fertility Rate (TFR) in Costa Rica

Dr. Smartson. P. NYONI Tatenda. A. CHIHOHO Thabani NYONI

Volume 5, Issue 8, August, PP  195-198

Projection of Total Fertility Rate in Belize

Dr. Smartson. P. NYONI Tatenda. A. CHIHOHO Thabani NYONI

Volume 5, Issue 8, August, PP  199-202

Projection of Total Fertility Rate (TFR) in Colombia

Dr. Smartson. P. NYONI Tatenda. A. CHIHOHO Thabani NYONI

Volume 5, Issue 8, August, PP  203-206

Forecasting Total Fertility Rate (TFR) in the Dominican Republic Using a Machine Learning Algorithm

Dr. Smartson. P. NYONI Tatenda. A. CHIHOHO Thabani NYONI

Volume 5, Issue 8, August, PP  207-210

Projecting Total Fertility Rates for Jordan Using Artificial Neural Networks

Dr. Smartson. P. NYONI Tatenda. A. CHIHOHO Thabani NYONI

Volume 5, Issue 8, August, PP  211-215

Forecasting Total Fertility Rate (TFR) in Morocco Using an Artificial Neural Network Approach

Dr. Smartson. P. NYONI Tatenda. A. CHIHOHO Thabani NYONI

Volume 5, Issue 8, August, PP  216-219

Projection of Total Fertility Rate (TFR) in Guinea Using a Machine Learning Technique

Dr. Smartson. P. NYONI Tatenda. A. CHIHOHO Thabani NYONI

Volume 5, Issue 8, August, PP  220-223

Machine Learning Application in Forecasting Total Fertility Rate (TFR) In Madagascar

Dr. Smartson. P. NYONI Tatenda. A. CHIHOHO Thabani NYONI

Volume 5, Issue 8, August, PP  224-227

Projection of Total Fertility Rate (TFR) in India

Dr. Smartson. P. NYONI Tatenda. A. CHIHOHO Thabani NYONI

Volume 5, Issue 8, August, PP  228-231

Time Series Forecasting of Total Fertility Rate (TFR) in Kenya

Dr. Smartson. P. NYONI Tatenda. A. CHIHOHO Thabani NYONI

Volume 5, Issue 8, August, PP  232-235

Forecasting Total Fertility Rate in Malawi

Dr. Smartson. P. NYONI Tatenda. A. CHIHOHO Thabani NYONI

Volume 5, Issue 8, August, PP  236-239

Time Series Forecasting of Total Fertility Rate (TFR) in Angola

Dr. Smartson. P. NYONI Tatenda. A. CHIHOHO Thabani NYONI

Volume 5, Issue 8, August, PP  240-243

Projection of Total Fertility Rate (TFR) in Iran

Dr. Smartson. P. NYONI Tatenda. A. CHIHOHO Thabani NYONI

Volume 5, Issue 8, August, PP  244-247

Projection of Total Fertility Rate (TFR) in Australia

Dr. Smartson. P. NYONI Tatenda. A. CHIHOHO Thabani NYONI

Volume 5, Issue 8, August, PP  248-251

Forecasting Total Fertility Rate in Mali Using a Machine Learning Technique

Dr. Smartson. P. NYONI Tatenda. A. CHIHOHO Thabani NYONI

Volume 5, Issue 8, August, PP  252-255

Univariate Time Series Analysis of Total Fertility Rate (TFR) in Mauritania

Dr. Smartson. P. NYONI Tatenda. A. CHIHOHO Thabani NYONI

Volume 5, Issue 8, August, PP  256-259

Projection of Total Fertility Rate (TFR) in Guinea Bissau

Dr. Smartson. P. NYONI Tatenda. A. CHIHOHO Thabani NYONI

Volume 5, Issue 8, August, PP  260-263

Projection of Total Fertility Rate in Malaysia

Dr. Smartson. P. NYONI Tatenda. A. CHIHOHO Thabani NYONI

Volume 5, Issue 8, August, PP  264-267

Univariate Time Series Forecasting of Total Fertility Rate in Mozambique

Dr. Smartson. P. NYONI Tatenda. A. CHIHOHO Thabani NYONI

Volume 5, Issue 8, August, PP  268-271

Forecasting Total Fertility Rate (TFR) in Libya

Dr. Smartson. P. NYONI Tatenda. A. CHIHOHO Thabani NYONI

Volume 5, Issue 8, August, PP  272-275

Predicting Future Trends of Total Fertility Rates in Kyrgzystan Using Artificial Neural Networks

Dr. Smartson. P. NYONI Tatenda. A. CHIHOHO Thabani NYONI

Volume 5, Issue 8, August, PP  276-280

Univariate Time Series Analysis of Total Fertility Rate (TFR) In Mauritius

Dr. Smartson. P. NYONI Tatenda. A. CHIHOHO Thabani NYONI

Volume 5, Issue 8, August, PP  281-284

Projection of Total Fertility Rate (TFR) in Iraq Using a Machine Learning Technique

Dr. Smartson. P. NYONI Tatenda. A. CHIHOHO Thabani NYONI

Volume 5, Issue 8, August, PP  285-288

Time Series Forecasting of Total Fertility Rate (TFR) in Lesotho

Dr. Smartson. P. NYONI Tatenda. A. CHIHOHO Thabani NYONI

Volume 5, Issue 8, August, PP  289-292

Projection of Total Fertility Rates in Guatemala Using Artificial Neural Networks

Dr. Smartson. P. NYONI Tatenda. A. CHIHOHO Thabani NYONI

Volume 5, Issue 8, August, PP  293-297

Projection of Total Fertility Rate (TFR) in Indonesia Using a Machine Learning Approach

Dr. Smartson. P. NYONI Tatenda. A. CHIHOHO Thabani NYONI

Volume 5, Issue 8, August, PP  298-301

Predicting Future Total Fertility Rates for Haiti Using Artificial Neural Networks

Dr. Smartson. P. NYONI Tatenda. A. CHIHOHO Thabani NYONI

Volume 5, Issue 8, August, PP  302-306

Projection of Total Fertility Rate in Honduras

Dr. Smartson. P. NYONI Tatenda. A. CHIHOHO Thabani NYONI

Volume 5, Issue 8, August, PP  307-310

Forecasting Total Fertility Rate (TFR) in Liberia

Dr. Smartson. P. NYONI Tatenda. A. CHIHOHO Thabani NYONI

Volume 5, Issue 8, August, PP  311-318

Projection of Total Fertility Rate (TFR) In Sao Tome and Principe

Dr. Smartson. P. NYONI Tatenda. A. CHIHOHO Thabani NYONI

Volume 5, Issue 8, August, PP  319-322

Forecasting Total Fertility Rate (TFR) In Sri Lanka Using a Machine Learning Algorithm

Dr. Smartson. P. NYONI Tatenda. A. CHIHOHO Thabani NYONI

Volume 5, Issue 8, August, PP  323-326

Forecasting Total Fertility Rate (TFR) In Namibia

Dr. Smartson. P. NYONI Tatenda. A. CHIHOHO Thabani NYONI

Volume 5, Issue 8, August, PP  327-330

Forecasting Total Fertility Rate (TFR) In Turkey Using the Multilayer Perceptron Neural Network

Dr. Smartson. P. NYONI Tatenda. A. CHIHOHO Thabani NYONI

Volume 5, Issue 8, August, PP  331-334

Forecasting Total Fertility Rate (TFR) In Niger

Dr. Smartson. P. NYONI Tatenda. A. CHIHOHO Thabani NYONI

Volume 5, Issue 8, August, PP  335-338

Forecasting Total Fertility Rate (TFR) In Syria

Dr. Smartson. P. NYONI Tatenda. A. CHIHOHO Thabani NYONI

Volume 5, Issue 8, August, PP  339-342

Forecasting Total Fertility Rate (TFR) In Somalia

Dr. Smartson. P. NYONI Tatenda. A. CHIHOHO Thabani NYONI

Volume 5, Issue 8, August, PP  343-346

Projection of Total Fertility Rate (TFR) In the United States of America Using a Machine Learning Approach

Dr. Smartson. P. NYONI Tatenda. A. CHIHOHO Thabani NYONI

Volume 5, Issue 8, August, PP  347-350

Forecasting Total Fertility Rate (TFR) In Sierra Leone Using a Machine Learning Method

Dr. Smartson. P. NYONI Tatenda. A. CHIHOHO Thabani NYONI

Volume 5, Issue 8, August, PP  351-354

Projection of Total Fertility Rate (TFR) In Yemen

Dr. Smartson. P. NYONI Tatenda. A. CHIHOHO Thabani NYONI

Volume 5, Issue 8, August, PP  355-358

Time Series Prediction of Total Fertility Rate in Rwanda

Dr. Smartson. P. NYONI Tatenda. A. CHIHOHO Thabani NYONI

Volume 5, Issue 8, August, PP  359-362

Forecasting Total Fertility Rate (TFR) In South Africa

Dr. Smartson. P. NYONI Tatenda. A. CHIHOHO Thabani NYONI

Volume 5, Issue 8, August, PP  363-366

Forecasting Total Fertility Rate (TFR) In Nigeria Using a Machine Learning Approach

Dr. Smartson. P. NYONI Tatenda. A. CHIHOHO Thabani NYONI

Volume 5, Issue 8, August, PP  367-370

Forecasting Total Fertility Rate (TFR) In Paraguay Using a Machine Learning Algorithm

Dr. Smartson. P. NYONI Tatenda. A. CHIHOHO Thabani NYONI

Volume 5, Issue 8, August, PP  371-374

Forecasting Total Fertility Rate (TFR) In Senegal

Dr. Smartson. P. NYONI Tatenda. A. CHIHOHO Thabani NYONI

Volume 5, Issue 8, August, PP  375-378

Projecting Total Fertility Rates for Oman Using Artificial Neural Networks

Dr. Smartson. P. NYONI Tatenda. A. CHIHOHO Thabani NYONI

Volume 5, Issue 8, August, PP  379-383

Forecasting Total Fertility Rate (TFR) In South Sudan

Dr. Smartson. P. NYONI Tatenda. A. CHIHOHO Thabani NYONI

Volume 5, Issue 8, August, PP  384-387

Forecasting Total Fertility Rate (TFR) In Slovenia

Dr. Smartson. P. NYONI Tatenda. A. CHIHOHO Thabani NYONI

Volume 5, Issue 8, August, PP  388-391

Time Series Forecasting Of Total Fertility Rate (TFR) In Saudi Arabia

Dr. Smartson. P. NYONI Tatenda. A. CHIHOHO Thabani NYONI

Volume 5, Issue 8, August, PP  392-395

Forecasting Total Fertility Rate (TFR) In Peru

Dr. Smartson. P. NYONI Tatenda. A. CHIHOHO Thabani NYONI

Volume 5, Issue 8, August, PP  396-399

Forecasting Total Fertility Rate (TFR) In Panama

Dr. Smartson. P. NYONI Tatenda. A. CHIHOHO Thabani NYONI

Volume 5, Issue 8, August, PP  400-403

Projection of Total Fertility Rate (TFR) in Romania

Dr. Smartson. P. NYONI Tatenda. A. CHIHOHO Thabani NYONI

Volume 5, Issue 8, August, PP  404-407

Projection of Total Fertility Rate (TFR) In Nepal

Dr. Smartson. P. NYONI Tatenda. A. CHIHOHO Thabani NYONI

Volume 5, Issue 8, August, PP  407-411

Forecasting Total Fertility Rate in Suriname

Dr. Smartson. P. NYONI Tatenda. A. CHIHOHO Thabani NYONI

Volume 5, Issue 8, August, PP  412-415

Projecting Future Total Fertility Rates in Solomon Islands Using Artificial Neural Networks

Dr. Smartson. P. NYONI Tatenda. A. CHIHOHO Thabani NYONI

Volume 5, Issue 8, August, PP  416-419

Artificial Intelligence Forecasting Of Total Fertility Rate (TFR) In Ghana

Dr. Smartson. P. NYONI Tatenda. A. CHIHOHO Thabani NYONI

Volume 5, Issue 8, August, PP  420-423

Time Series Forecasting Of Total Fertility Rate (TFR) In Tanzania

Dr. Smartson. P. NYONI Tatenda. A. CHIHOHO Thabani NYONI

Volume 5, Issue 8, August, PP  424-427

Predicting Future Trends of Total Fertility Rates in Fiji Using Artificial Neural Networks

Dr. Smartson. P. NYONI Tatenda. A. CHIHOHO Thabani NYONI

Volume 5, Issue 8, August, PP  428-432

Forecasting Total Fertility Rate (TFR) In Gabon

Dr. Smartson. P. NYONI Tatenda. A. CHIHOHO Thabani NYONI

Volume 5, Issue 8, August, PP  433-436

Time Series Forecasting of Total Fertility Rate (TFR) in Zambia

Dr. Smartson. P. NYONI Tatenda. A. CHIHOHO Thabani NYONI

Volume 5, Issue 8, August, PP  437-440

Forecasting Total Fertility Rate (TFR) In Togo

Dr. Smartson. P. NYONI Tatenda. A. CHIHOHO Thabani NYONI

Volume 5, Issue 8, August, PP  441-444

Projection of Total Fertility Rate (TFR) In the Gambia Using an Artificial Neural Network Approach

Dr. Smartson. P. NYONI Tatenda. A. CHIHOHO Thabani NYONI

Volume 5, Issue 8, August, PP  445-448

Forecasting Total Fertility Rate in Thailand

Dr. Smartson. P. NYONI Tatenda. A. CHIHOHO Thabani NYONI

Volume 5, Issue 8, August, PP  449-452

Forecasting Total Fertility Rate (TFR) in Vietnam

Dr. Smartson. P. NYONI Tatenda. A. CHIHOHO Thabani NYONI

Volume 5, Issue 8, August, PP  453-456

Total Fertility Rate (TFR) Forecasting In Algeria

Dr. Smartson. P. NYONI Tatenda. A. CHIHOHO Thabani NYONI

Volume 5, Issue 8, August, PP  457-460

Projecting Future Total Fertility Rates for Tajikistan Using Artificial Neural Networks

Dr. Smartson. P. NYONI Tatenda. A. CHIHOHO Thabani NYONI

Volume 5, Issue 8, August, PP  461-465

Predicting Total Fertility Rates for Turkmenistan Using Artificial Neural Networks

Dr. Smartson. P. NYONI Tatenda. A. CHIHOHO Thabani NYONI

Volume 5, Issue 8, August, PP  466-469

Forecasting Total Fertility Rate (TFR) In Tunisia

Dr. Smartson. P. NYONI Tatenda. A. CHIHOHO Thabani NYONI

Volume 5, Issue 8, August, PP  470-473

Time Series Forecasting Of Total Fertility Rate (TFR) In Uganda

Dr. Smartson. P. NYONI Tatenda. A. CHIHOHO Thabani NYONI

Volume 5, Issue 8, August, PP  474-477

Time Series Forecasting Of Total Fertility Rate in Zimbabwe

Dr. Smartson. P. NYONI Tatenda. A. CHIHOHO Thabani NYONI

Volume 5, Issue 8, August, PP  478-481

Projection of Total Fertility Rate (TFR) In Venezuela

Dr. Smartson. P. NYONI Tatenda. A. CHIHOHO Thabani NYONI

Volume 5, Issue 8, August, PP  482-485

Forecasting Total Fertility Rate (TFR) In Uzbekistan

Dr. Smartson. P. NYONI Tatenda. A. CHIHOHO Thabani NYONI

Volume 5, Issue 8, August, PP  486-489

Forecasting Total Fertility Rate (TFR) In the United Arab Emirates (UAE)

Dr. Smartson. P. NYONI Tatenda. A. CHIHOHO Thabani NYONI

Volume 5, Issue 8, August, PP  490-493

Forecasting Total Fertility Rate (TFR) In Albania Using a Machine Learning Algorithm

Dr. Smartson. P. NYONI Tatenda. A. CHIHOHO Thabani NYONI

Volume 5, Issue 8, August, PP  494-497

Time Series Forecasting Of Total Fertility Rate (TFR) In Sudan

Dr. Smartson. P. NYONI Tatenda. A. CHIHOHO Thabani NYONI

Volume 5, Issue 8, August, PP  498-501

Projection of Total Fertility Rate in New Zealand

Dr. Smartson. P. NYONI Tatenda. A. CHIHOHO Thabani NYONI

Volume 5, Issue 8, August, PP  502-505

An Analysis of Knowledge of Sexual and Reproductive Health among Adolescents and Young Persons Living with HIV: The Case of Chitungwiza, Harare, Zimbabwe

Lianora MANYANGE Smartson. P. NYONI Norman MAKUNIKA Thabani NYONI

Volume 5, Issue 8, August, PP  506-520